husqvarna service training – advanced...

Husqvarna Service Training – Advanced Level Overview The requirement for all students wishing to progress to the advanced level certification, is the completion of the Husqvarna University Service Training - Basic levels first. The advanced level course consists of two modules for both Handheld and Wheeled products, namely: Module 1: - Troubleshooting Module 2: - Maintenance The course is designed to be instructor led, as there are elements of hands-on as well as theory followed by a practical and written examination. The training duration for both Handheld and Wheeled is estimated to be 2–3 days each, depending on: - products used, level of participation, number of hands-on exercises done, number of participants, etc. It is recommended to have 8–10 participants per training course. An example of how a course can be structured is as follows: Day 1 - Theory (Troubleshooting methods, processes, identifying symptoms, finding the primary fault, secondary effects, causes, preventative maintenance, etc) Day 2 – Practical (Identifying symptoms, fault finding, actions, analysing the causes, correct repair, maintenance and identification of worn parts) Day 3 – Practical (As above if more examples are required), followed by a practical and written examination The course material will be in the form of a binder for the instructor and will consist of: Module 1 – Troubleshooting • Introduction to Troubleshooting • Troubleshooting theory • Troubleshooting practical (Instruction suggestions on how to set-up the practical examples)

Module 2 – Maintenance

• Maintenance Theory • List of suggested “props” to use for the training Written & practical examination

RPL (Recognition of Prior Learning) will be taken into account in the form of a written pre-test. This pre-test will have a pass mark of 90%. If successful, the student is deemed to be competent and certified. A certified student is still very welcome to participate in a training session for further education and, of course, to share their knowledge with others. Remember that there are many other sources of training material available from Husqvarna that can be used as a complimentary reference to this training. We hope this brief introduction to the Husqvarna Advanced Level Training is beneficial for you and can assist you when preparing your training programmes. Good Luck!

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Husqvarna Service Training Handheld – Advanced Level Contents

Module 1 - Troubleshooting

Troubleshooting introduction…..…………………………………… 5 Troubleshooting overview. …………………………………………. 6 Troubleshooting theory & practical:

Engine…………………………………………………………….. 9

Drive System……………………………………………………. 47

Lubrication System……………………………………………... 61

Cutting Equipment……………………………………………… 69

Module 2 - Maintenance

Maintenance Introduction……………………………………………. 77

Preventative Maintenance Checklist..………………………… 78

Worn Parts identification & Analysis ………………………….. 79 P.D.I and Basic Service Guideline…..………………………… 85

Instructor Notes

Training “tool-box” ……………………………………………………. 89

Tips for practical examination marking…………………………..… 91

Examination…………………………………………………………….93

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Module 1 – Troubleshooting Introduction Troubleshooting consists of diagnosing a symptom or analyzing a component in an efficient and logically systematic manner in order to save time and maximise workshop profitability when repair takes place. In all troubleshooting cases, it is important to cover the basics first in order to eliminate the obvious. In a lot of troubleshooting cases, the root cause is often found to have a simple answer. Customer abuse and lack of maintenance (normally due to inexperience and lack of training) is also the result of many troubleshooting journeys. Normal wear & tear of components is the most common cause of troubleshooting symptoms. The art of efficient troubleshooting is very often experienced based and is a continuous learning process which, when done correctly, should answer most of the questions: How?

Why?

What?

Where?

Who? There can be, however, many different reasons and causes to a single symptom and sometimes the reason just has no logical explanation at all! Troubleshooting is therefore not an exact science but tends to be more of a common sense exercise. Effective troubleshooting requires a good knowledge of how components wear and why, how products are used and also to recognize the cause & effect principle.

Tips for effective troubleshooting • Gather all the facts • Use your senses • Eliminate the basics first

This module will provide you with: • Various common symptoms and the diagnosis thereof • What the primary faults could be and the supporting evidence • What actions should be taken to verify your suspicions • If there are any secondary component effects, caused by the primary fault • What the root causes and preventative solutions could be

Troubleshooting areas covered in this module include: • Engine • Drive Systems • Lubrication Systems • Cutting Equipment

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Troubleshooting overview (Theory & Practical)

Common Symptoms Possible causes Page Engine 1. Engine not starting

a. Flooded ............................................ 13, 14 b. Carburetor ........................................ 15, 16 c. Low Compression.…………………… 17, 18 d. Air leak or blockage .....................…. 19, 20 e. Flywheel key .................................…. 21, 22

2. Idling problems –

Not idling, idling too rich or idling uneven

a. Carburetor ....................................... 23, 24 b. Fuel tank breather .......................…. 25, 26 c. Air leak ......................…................... 27, 28 d. Worn piston & ring(s)....………....….. 29, 30 e. Clutch failure ...........…..................... 31, 32

3. Acceleration, power and performance problems

a. Carburetor ...................................….. 33, 34 b. Fuel tank breather ....................…..... 35, 36 c. Manifold leaking ........................…… 37, 38 d. Blocked muffler .........................…... 39, 40 e. Ignition system ...........................….. 41, 42

4. Running ability – other

a. Piston and cylinder seized.....…….... 43, 44 b. Main bearings or crankshaft

big-end bearing damaged ................. 45, 46

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Troubleshooting overview (Theory & Practical)

Common Symptoms Possible causes Page Drive systems 1. Cutting equipment or attachment engaged all the time

a. Clutch ..............................…….......… 47, 48 b. Clutch drum bearing ...............……... 49, 50

2. Cutting equipment or attachment will hardly engage or will not engage at all, at full throttle

(i.e. chainsaw chain, trimmy head or brushcutter blade, etc)

a. Clutch ......................................……... 51, 52 b. Gearbox .....................................…… 53, 54 c. Drive shaft or belt ....................……... 55, 56 d. Brake band ................................……. 57, 58 e. Rim sprocket .............................……. 59, 60

Lubrication Systems 1. Oiling Problem (General)

a. Oil pump ……..................................... 63 b. Worm gear (drive wheel)……………... 64 c. Oil hose and pickup…………….….… 65 d. Oil tank, tank cap and breather……… 66

e. Guide bar………………………………. 67

Cutting equipment 1. Chainsaw guide bar and chain ...........………………………………………..…. 69 2. Cutting equipment – general………………………………………………………. 73

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Troubleshooting Theory - Engine From an engine not starting to an engine with a poor running performance, there are three basic areas that should be investigated first to eliminate the obvious. These areas with their basic associated components are: Fuel - Carburetor, Fuel filter, Fuel mix, Hoses, Primer bulb, Breather Spark - Spark Plug, Ignition unit, HT & short Lead, Stop Switch, Flywheel Air - Air filter, Carburetor, Manifold, Muffler, Hoses, Breather The minimum requirements an engine needs to function are fuel, spark and air. The associated components of these three areas must therefore all be in a good working order. Checks surrounding these components form the Basic “first step” checks. Engine Compression has also been considered and included as part of the Basic “first step” checks:

Section 1: Basics • Pull the starter rope to see if the engine turns over and if compression is adequate*

* Remove the exhaust to check for piston seizure or ring damage if compression seems inadequate

• Check fuel for quantity and correct mix – recommend to replace with a known mix

• Check the fuel filter for blockage

• Check the carburetor settings are correct (including the idle adjustment)

• Check for spark

• Check spark plug electrode for wear or carbon build up & gap

• Check the air filter for blockage

• Check the muffler spark arrestor screen, if fitted

• Visually check hoses, manifold and cylinder base gasket for leaks

As these “Basic” checks form an important part of any troubleshooting journey, a flow-chart of these checks, to simplify the process, is included:

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Troubleshooting Theory – Engine Section 1: Basics Flow-chart If the Basic checks do not reveal the cause of the problem, further investigation of various components will be necessary. These possible primary-fault checks will be referred to during the symptom analysis, as and when required, and are categorised as follows: Section 2: Carburetor

Section 3: Engine Components

Section 4: Ignition System

Spark

Air

Fuel

Check fuel (Remove existing fuel and replace with good, known mix)

Check the fuel filter for blockage

Check the carburetor settings are correct

Check the air filter for blockage

Check the muffler spark arrestor screen for blockage, if fitted

Check for spark

Pull the starter rope to check compression

Compression

If compression is low or “too high”, remove the exhaust to check for piston or ring damage. (Starting problems or piston seized)

Compression OK

Fuel OK

Check spark plug if wet or dry & check electrode for wear, carbon build-up & correct gap

Spark OK

In addition to all the above: Visually check hoses, manifold and cylinder base gasket for leaks

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Troubleshooting Theory - Engine Section 2: Carburetor – Possible Primary Faults • Check needle and metering lever for wear or adjustment– (flooding, uneven rpm)

• Check that the carburetor assembly screws and the carburetor covers are correctly tightened

(idle problems, runs lean)

* Pressure testing the carburetor will reveal a leak immediately and narrow the search

• Check the setting screws for tip damage caused from over tightening (starting problems)

• Check diaphragms for wear or hardness (idle, starting problems)

• Check diaphragms & gaskets correctly installed (starting problems)

• Check sieves or inlet screens for blockage (running, starting problems)

• Check throttle and choke butterfly’s & shafts for wear (Idle, running problems)

• Check the impulse hose for blockage or air leaks (starting, running problems)

• Check the tank vent / breather for blockage (engine cuts out after 5–10 minutes)

• Check the manifold for air leaks (runs lean, low power)

Section 3: Engine Components – Possible Primary Faults • Check for low compression (starting & idle problems, cuts out when hot, low power)

• Check the decompression valve functionality (low compression, low power)

• Check the muffler and spark arrestor screen for blockage (low power, no high rpm)

• Check the cylinder exhaust port for blockage (low power, no high rpm)

• Check the cylinder, piston and ring(s) for wear (idle problems, runs rough, low power)

• Check seals, o’rings and gaskets for wear and leakage - vacuum / pressure test (starting

problems, runs lean)

• Check the crankshaft bearings and main carrier bearings for wear (noisy, engine runs rough)

• Check the crankcase and crankcase gaskets for leakage (runs lean)

Section 4: Ignition System – Possible Primary Faults • Check for correct grounding (earthing) and stop switch functionality (not starting or can’t switch

the engine off)

• Check for short leads worn through the insulation and causing intermittent faults

• Check the ignition module air gap (0.3mm) from the flywheel magnets (starting problems, runs

erratically)

• Check that the HT lead is not damaged and spark plug cap are in tact and correctly fitted (not

starting) Note: The HT lead can wear and short on the cylinder fin / flywheel

• Check that the flywheel key is not sheared causing incorrect spark timing (not starting)

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Stop switch in the OFF position. Remove spark plug, turn the engine upside-down and pull the starter 8-10 times to purge excess fuel from the cylinder. Refit spark plug and without using choke, attempt to start the engine. See Section 2: Carburetors, for other possible areas to check if the problem is not solved

1. Engine not starting Check basics first (Section 1: Basics)

a. Flooded

Spark plug wet with fuel and the muffler smells of fuel

Check air filter for fuel saturation

• Trying to start the engine with the stop switch in the off position

• Using the choke when the engine is warm • Air filter blocked, which chokes the engine with too much fuel • Carburetor needle or the metering lever are worn or the lever

is incorrectly adjusted

Supporting evidence

Action

Possible secondary effects

Possible primary fault

Possible causes of the primary fault

Troubleshooting Theory – Engine 1. Engine not starting a. Flooded

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1. Engine not starting

a. Flooded

• Attempt to start the engine with the stop switch in the off position. 10-15 pulls should be sufficient

• Attempt to start using the choke when the engine is warm • Adjust the carburetor metering lever too high

Set-up options


Troubleshooting Practical – Engine 1. Engine not starting a. Flooded

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Troubleshooting Theory – Engine 1. Engine not starting b. Carburetor

Remove carburetor & check for loose covers. (If fitting a good carburetor solves the problem then you know to continue dismantling the original) Pressure testing the carburetor (50kPa) will reveal if any air leaks. Check diaphragms, needle & lever, choke shaft & throttle shaft for wear or sticking. Check sieve and hoses for blockage. Check the setting screws for tip breakage.


b. Carburetor

Spark plug dry and no smell of fuel present

No secondary components effected

• Diaphragms are worn or the engine has been standing for a period of time and the diaphragms have gone hard and are no longer effective. Diaphragms fitted incorrectly

• Fuel or impulse hoses completely blocked with dirt • Carburetor sieves blocked with dirt • Choke or throttle shafts worn through normal wear and tear

or worn due to increased engine vibrations • See Section 2: Carburetors, for other possible areas to check

if the problem persists

Supporting evidence

Action




Instructor note: Hot starting problems could be encountered from time to time and can be a result of “vapour locking”. This is when the fuel in the carburetor “boils” and changes form from a liquid to a vapour. This vapour is not sufficient for fuel delivery into the engine and it will not start. To start an engine that is vapour locked: Either wait until the fuel cools down or use the choke to get a rich mixture through the carburetor to cool the fuel and overcome the vapour lock. Common causes of vapour locking include: Blocked tank breather, Winter plug missing and working in very high ambient temperatures.

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b. Carburetor

• Fit Diaphragms and gaskets incorrectly • Block fuel or impulse hoses with a piece of cloth • Block carburetor sieves with tape

Set-up options


Troubleshooting Practical – Engine 1. Engine not starting b. Carburetor

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Remove cylinder and inspect the piston, ring(s) and cylinder for wear or ring sticking


c. Low Compression

It is much easier to pull the starter compared to a new engine (Starting problems when hot)

Check the crankshaft big-end bearing and main bearings for wear

• Normal wear & tear of the piston, ring(s) or cylinder • Premature wear due to the air filter being damaged or

ineffective to the entry of dirt & dust particles into the engine • Premature wear or ring sticking due to a too rich fuel mix or

an inferior 2-stoke oil quality being used which allows for the rapid and excessive build-up of abrasive carbon.

Note* A worn piston or ring(s) will not hold compression when run to operating temperature. The engine will often cut out and will be difficult to start. (Make sure the decompression valve is not causing the low compression suspicion) Make sure that there is no carbon build-up in the piston ring groove before fitting a new piston ring

Supporting evidence

Action




Troubleshooting Theory – Engine 1. Engine not starting c. Low Compression

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c. Low Compression

• Fit a worn piston, ring(s) or cylinder Set-up options


Troubleshooting Practical – Engine 1. Engine not starting c. Low Compression

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Troubleshooting Theory – Engine 1. Engine not starting d. Air leak or blockage

Perform a crankcase vacuum / pressure test (80 kPa pressure) to find the possible air leak. Check fuel / impulse tube & muffler for blockage * Make sure the pressure / vacuum tests are performed within the specification of engine. Check the applicable Workshop Manuals


d. Air leak or blockage

Crankshaft seals, crankcase, cylinder base gasket, manifold, spark plug compression seal or fuel hoses show signs of leaking (wet area with dirt and dust attracted to it). The fuel / impulse hoses or muffler could also be blocked

Check piston and cylinder for high speed scuffing

• Seals are hard from standing for a long period of time or worn through normal use

• Hoses perish through time if exposed to the elements and by certain fuel types

• Gaskets could be blown due to excessive engine heat • Muffler could be blocked due to carbon build-up • Hoses could be blocked from dirt

Supporting evidence

Action




Instructor note: When pressure testing a powercutter crankcase, make sure the crankshaft lubrication hole for the clutch drum bearing, is sealed.

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d. Air leak or blockage

• Damage one of the seals by making a hole with a screwdriver • Make a hole in the fuel hose or manifold • Tear a section out of the base gasket then refit • Block the cylinder exhaust port with a piece of rubber • Block the fuel hose or impulse hose with a piece of cloth

Set-up options


Troubleshooting Practical – Engine 1. Engine not starting d. Air leak or blockage

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Remove the flywheel and check if the key is not damaged


e. Flywheel Key

If the key is sheared, spark will be present but the timing will be out

Check the crankshaft (flywheel) threads and flywheel nut are not damaged

• Flywheel nut not secured properly, comes loose and the flywheel key is sheared off by the rotating crankshaft

• Flywheel fins get jammed by a foreign object while the engine is running, causing the key to shear

• The flywheel not fitted correctly by aligning the key into the crankshaft key-way

Note* Incorrectly maintained cutting equipment could also aggravate a sheared flywheel key situation due to increased vibrations

Supporting evidence

Action




Troubleshooting Theory – Engine 1. Engine not starting e. Flywheel Key

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e. Flywheel Key

• Fit a flywheel with a sheared key by deliberately putting the timing out

Set-up options


Troubleshooting Practical – Engine 1. Engine not starting e. Flywheel Key

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Remove carburetor & check for loose covers. Check diaphragms, needle, and lever, choke shaft & throttle shaft for wear or sticking. Make sure the idle screw friction ball is in place (if applicable)

2. Idling problems – Not idling, idling too rich or idling uneven

Check basics first (Section 1: Basics)

a. Carburetor

Difficult to adjust the carburetor


• Diaphragms are worn through normal wear and tear • Fuel or impulse hoses partially blocked with dirt • Carburetor sieves partially blocked with dirt • Choke or throttle shafts worn through normal wear and

tear or worn due to increased engine vibrations • See Section 2: Carburetors, for other possible areas to

check if the problem persists

Supporting evidence

Action




Troubleshooting Theory – Engine 2. Idling problems - Not idling, idling too rich or idling uneven a. Carburetor

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a. Carburetor

• Fit worn diaphragms • Partially block the fuel or impulse hose with some cloth • Partially block carburetor sieves with tape • Fit worn choke or throttle shafts

Set-up options


Troubleshooting Practical – Engine 2. Idling problems - Not idling, idling too rich or idling uneven a. Carburetor

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Check the breather from the outside (if applicable) for dirt build up alternatively pressure test the fuel tank to check for a blocked tank vent / breather. Note that there are various tank vent types.



b. Fuel tank breather

Idle uneven and engine cuts out after 5 - 10 minutes


• Breather gets blocked with dirt either from the outside or from dirt that enters the fuel tank when refueling

• See Section 2: Carburetors, for other possible areas to check if the problem persists

Supporting evidence

Action




Troubleshooting Theory – Engine 2. Idling problems - Not idling, idling too rich or idling uneven b. Fuel tank breather

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• Block the fuel tank breather with some cloth or paper Set-up options


Troubleshooting Practical – Engine 2. Idling problems - Not idling, idling too rich or idling uneven b. Fuel tank breather

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Perform a crankcase vacuum / pressure test to isolate the source of the possible air leak



c. Air leak

Crankshaft seals, crankcase, cylinder base gasket, manifold, spark plug compression seal or fuel hoses show signs of leaking (wet area with dirt and dust attracted to it).

Check piston and cylinder for high speed scuffing

• Seals are hard from standing for a long period of time or worn through normal use

• Hoses perish through time if exposed to the elements and by certain fuel types

• Gaskets could be blown due to excessive engine heat • The manifold could be punctured or cracked due to

vibration • The cylinder base could be cracked due to over

tightening

Supporting evidence

Action




Troubleshooting Theory – Engine 2. Idling problems - Not idling, idling too rich or idling uneven c. Air leak

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c. Air leak

• Damage one of the seals by making a hole with a screwdriver

• Make a hole in the fuel hose or manifold • Tear a section out of the base gasket then refit

Set-up options


Troubleshooting Practical – Engine 2. Idling problems - Not idling, idling too rich or idling uneven c. Air leak

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Perform a compression test. If compression is found to be low, remove cylinder and inspect the piston and ring(s) for wear



d. Worn piston & ring(s)

Engine does not hold idle and cuts out when hot, then it is difficult to start

Check seals, cylinder and main bearings for wear

• Normal wear & tear of the piston & ring(s) • Premature wear due to the air filter being damaged or

worn and is rendered ineffective to the entry of dirt & dust particles into the engine

• Premature wear or ring sticking due to a too rich fuel mix or an inferior 2-stoke oil quality being used allows for the rapid and excessive build-up of abrasive carbon.

Note* A worn piston or ring(s) will not hold compression when run to operating temperature. The engine will often cut out and will be difficult to start until it cools down. Make sure that there is no carbon build-up in the piston ring groove before fitting a new piston ring

Supporting evidence

Action




Troubleshooting Theory – Engine 2. Idling problems - Not idling, idling too rich or idling uneven d. Worn piston & ring(s)

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d. Worn piston & ring(s)

• Fit a worn piston & ring(s) • Fit a piston with a stuck ring

(Make sure the engine is run to full operating temperature to check the symptoms)

Set-up options


Troubleshooting Practical – Engine 2. Idling problems - Not idling, idling too rich or idling uneven d. Worn piston & ring(s)

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Remove the clutch cover to inspect the clutch and clutch drum



e. Clutch failure

Cutting equipment constantly engaged at idle and causes engine to cut out

Check clutch drum bearing

• Dirt build up between the clutch shoes and clutch drum • Clutch springs damaged or worn (overheating causes

clutch springs to loose tension) • Clutch drum bearing seized due to lack of lubrication • Clutch damaged due to constant slippage and

overheating Note* Clutch shoes and springs should always be replaced in sets

Supporting evidence

Action




Troubleshooting Theory – Engine 2. Idling problems - Not idling, idling too rich or idling uneven e. Clutch failure

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e. Clutch failure

• Fit worn or stretched clutch springs • Jam the clutch shoes in the open position against the clutch

drum

Set-up options


Troubleshooting Practical – Engine 2. Idling problems - Not idling, idling too rich or idling uneven e. Clutch failure

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Remove the carburetor & check for loose covers. Check the diaphragms, needle and lever, choke shaft & throttle shaft for wear or sticking

3. Acceleration, power & performance problems


a. Carburetor

Difficult to adjust the carburetor and engine will not reach maximum RPM. Engine could cut out when throttle is released


• Diaphragms, needle or the metering lever are worn through normal wear and tear or the lever is incorrectly adjusted

• Fuel or impulse hoses partially blocked with dirt • Carburetor sieves partially blocked with dirt • Choke or throttle shafts worn through normal wear and

tear or worn due to increased engine vibrations • See Section 2: Carburetors, for other possible areas to

check if the problem persists

Supporting evidence

Action




Troubleshooting Theory – Engine 3. Acceleration, power and performance problems a. Carburetor

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a. Carburetor

• Incorrectly adjust the metering lever • Incorrectly adjust the carburetor setting screws • Partially block the fuel or impulse hose with some cloth • Partially block carburetor sieves with tape • Fit worn choke or throttle shafts

Set-up options


Troubleshooting Practical – Engine 3. Acceleration, power and performance problems a. Carburetor

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Check the breather from the outside (if applicable) for dirt build up alternatively pressure test the fuel tank to check for a blocked tank vent / breather




Idle uneven and engine cuts out after 5 - 10 minutes – lack of power


• Breather gets blocked with dirt either from the outside or from dirt that enters the fuel tank when refueling

• See Section 2: Carburetors, for other possible areas to check if the problem persists

Supporting evidence

Action




Troubleshooting Theory – Engine 3. Acceleration, power and performance problems b. Fuel tank breather

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• Block the fuel tank breather with some cloth or paper Set-up options


Troubleshooting Practical – Engine 3. Acceleration, power and performance problems b. Fuel tank breather

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Remove and visually inspect the manifold to isolate the source of the possible air leak



c. Manifold leaking

Manifold show signs of leaking and the engine will run erratically upon acceleration – lack of power

Prolonged engine use with a damaged manifold can lead to a piston & cylinder seizure

• Manifold could perish through time if exposed to the elements and by certain fuel types

• Manifold could be cracked due to vibration • Manifold could come loose due to vibration • An air leak at the manifold will allow more air to enter the

engine and will render the air / fuel ratio too lean during the acceleration process. The rpm will not be constant at “no load speed” and if the problem is not attended to, could cause further engine damage.

Supporting evidence

Action




Troubleshooting Theory – Engine 3. Acceleration, power and performance problems c. Manifold leaking

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c. Manifold leaking

• Make a hole in the manifold with a screwdriver • Loosen the manifold from the carburetor or cylinder

Set-up options


Troubleshooting Practical – Engine 3. Acceleration, power and performance problems c. Manifold leaking

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Remove the muffler and check for blockage. Also check the spark arrestor screen



d. Blocked muffler

Engine does not accelerate and could cut out at full throttle - lack of power

Check cylinder exhaust port, piston crown and spark plug electrode for carbon build-up

• Muffler, spark arrestor screen or cylinder exhaust port blocked due to a too rich fuel mix or an inferior 2-stoke oil quality being used which allows for the rapid and excessive build-up of carbon.

A blocked muffler will not allow the exhaust gases to escape, which causes a back pressure of gases into the engine and retards the acceleration process. A lack of power and performance will also be noticed.

Supporting evidence

Action




Troubleshooting Theory – Engine 3. Acceleration, power and performance problems d. Blocked muffler

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d. Blocked muffler

• Partially block the cylinder exhaust port with a piece of rubber

• Partially block the spark arrestor screen with some tape

Set-up options


Troubleshooting Practical – Engine 3. Acceleration, power and performance problems d. Blocked muffler

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Check the ignition air gap, flywheel key, HT lead, sparkplug cap and sparkplug



e. Ignition system

Engine will not reach full RPM and misfires – lack of power

Check flywheel for damage from ignition module coming loose. Check the spark plug for carbon build-up

• A carbon “bead” could form between the sparkplug electrodes if a too rich fuel mix or an inferior 2-stoke oil quality being used. This would cause the engine to cut out suddenly when normal operation is taking place. The same could occur if the engine is forced under load for a too long period.

• The ignition module could come loose (due to vibration or not tightened correctly) and run against the flywheel. This would upset the spark strength, consistency and timing, causing poor acceleration. Evidence of this is scratch marks on the flywheel magnets and counterweights.

• The flywheel key, if sheared, may turn slightly out of time, which would effect the engine performance.

Supporting evidence

Action




Troubleshooting Theory – Engine 3. Acceleration, power and performance problems e. Ignition system

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e. Ignition system

• Increase the CD unit gap to simulate a loose CD unit • Increase the spark plug electrode gap to simulate an

incorrectly functioning spark plug

Set-up options


Troubleshooting Practical – Engine 3. Acceleration, power and performance problems e. Ignition system

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Remove cylinder and inspect cylinder lining, piston and ring(s) for signs of a heat seizure or damage. Check for foreign object entry, bearing cage / bearing needle or piston circlip that would cause the piston to lock up. Check that the piston ring locating pin is in place

4. Running Ability - other Check basics first (Section 1: Basics)

a. Piston and Cylinder seized

Engine does not turn over when the starter rope is pulled

Check crankshaft big-end and main bearings for damage and wear. Change crankcase seals.

• Incorrect 2-stroke oil or incorrect mixing ratio used • Incorrect carburetor settings • Air leak possibly from fuel hoses, seals, manifold or

gaskets • Dirty cylinder cooling fins or the air intake on the starter

housing blocked • Air conductor missing or broken • Water contamination in the fuel supply • Foreign object entering the engine through the

carburetor (i.e. choke flap screw) or one of the piston pin circlips came adrift

Supporting evidence

Action




Troubleshooting Theory – Engine 4. Running Ability – other a. Piston and cylinder seized

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4. Running Ability - other

a. Piston and Cylinder seized

• Either run a machine with unmixed fuel until it seizes or fit a seized piston and/or cylinder onto an engine

• Either place a foreign object through the carburetor with the machine running or fit a cylinder and piston previously damaged due to a foreign object

Set-up options


Troubleshooting Practical – Engine 4. Running Ability – other a. Piston and cylinder seized

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Troubleshooting Theory – Engine 4. Running Ability – other b. Main bearings or crankshaft big-end bearing damaged

Remove the cylinder and piston and inspect the crankshaft big-end bearing for signs of excessive heat (bluing) or collapse. Move the con-rod up and down to check for movement in the big-end and main bearings. Rotate the crankshaft using the conrod to check for roughness in the main bearings

4. Running Ability - other Check basics first (Section 1: Basics)

b. Main bearings or crankshaft big-end bearing damaged

The engine starts and it runs but sounds rough. A knocking noise could be heard

Check cylinder and piston for damage. Change crankcase seals. In the case of main bearing damage, check for crankcase wear at the bearing housing

• Dirt or dust entry due to damaged or worn air filter • Over revving • Incorrect 2-stroke oil or incorrect mixing ratio used (a too

rich fuel mixture will cause black residues to form on the main bearing cages and will result in bearing damage)

• Incorrect carburetor settings • Air leak possibly from fuel hoses, seals, manifold or

gaskets • Inferior or wrong main bearings used (not correctly rated)

Supporting evidence

Action




Instructor note: Dirt or dust entry into the engine from a damaged or worn air filter is one of the biggest causes of bearing damage.

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4. Running Ability - other

b. Main bearings or crankshaft big-end bearing damaged

• Fit a crankshaft with either damaged / seized main bearings or big-end bearing

Set-up options


Troubleshooting Practical – Engine 4. Running Ability – other b. Main bearings or crankshaft big-end bearing damaged

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Troubleshooting Theory – Drive Systems The drive system includes those components that convert the power from the engine to the device being driven. These components normally consist of the following: • Clutch • Clutch Drum • Drive Sprocket (chainsaws) • Drive shaft (brushcutters) • Gearbox (brushcutters / hedgetrimmers) • Belt (powercutters)

1. Cutting equipment or attachment constantly engaged a. Clutch

Remove the clutch cover (and clutch drum if inboard clutch system) and inspect the clutch and springs for wear or damage

1. Cutting equipment or attachment constantly engaged


a. Clutch

When starting or at idle, the cutting equipment or attachment is engaged.

Check the clutch drum, sprocket and clutch drum bearing

• Clutch springs worn or broken and causing the clutch shoes to engage against the clutch drum unintentionally

• Dirt build-up between the clutch shoes and clutch drum causes the drum to engage prematurely

Supporting evidence

Action




48

Troubleshooting Practical – Drive Systems 1. Cutting equipment or attachment constantly engaged a. Clutch


a. Clutch

• Fit worn or stretched clutch springs Set-up options


49

Troubleshooting Theory – Drive Systems 1. Cutting equipment or attachment constantly engaged b. Clutch drum bearing

Remove the clutch cover and clutch drum and inspect the clutch drum bearing for seizure



b. Clutch drum bearing

When starting or at idle, the cutting equipment or attachment is engaged

Check the clutch drum and crankshaft main journal bearing surface

• Clutch drum bearing is seized and causes the clutch drum to engage with the crankshaft unintentionally

The clutch drum bearing requires grease on a regular basis to ensure it does not seize

Supporting evidence

Action




50

Troubleshooting Practical – Drive Systems 1. Cutting equipment or attachment constantly engaged b. Clutch drum bearing


b. Clutch drum bearing

• Fit the clutch drum bearing using Loctite on both the crankshaft and clutch drum to simulate a seized bearing

Set-up options


51

Troubleshooting Theory – Drive Systems 2. Cutting equipment or attachment will not engage during full throttle a. Clutch

Inspect the clutch spyder and shoes for jamming or sticking

2. Cutting equipment or attachment will not engage


a. Clutch

Engine reaches full RPM but the attachment does not engage

Check the clutch drum bearing for damage

• The clutch shoes could be stuck to the clutch spyder (rust, dirt) which would not allow the clutch to engage against the clutch drum

Supporting evidence

Action




52

Troubleshooting Practical – Drive Systems 2. Cutting equipment or attachment will not engage during full throttle a. Clutch


a. Clutch

• Fix the clutch shoes to the spyder with glue to simulate a seized clutch

Set-up options


53

Troubleshooting Theory – Drive Systems 2. Cutting equipment or attachment will not engage during full throttle b. Gearbox

Remove the gearbox. Hold the input shaft firm and attempt to rotate the output shaft. If the output shaft rotates, the gears are more than likely stripped



b. Gearbox


Check the drive shaft and splines for damage (brushcutter)

• Lack of grease • Unbalanced blades (damage gears) • Hitting a hard object with a blade (damage gears)

Supporting evidence

Action




54

Troubleshooting Practical – Drive Systems 2. Cutting equipment or attachment will not engage during full throttle b. Gearbox


b. Gearbox

• Fit a gearbox with stripped gears onto the unit Set-up options


55

Troubleshooting Theory – Drive Systems 2. Cutting equipment or attachment will not engage during full throttle c. Drive shaft or belt

Check the drive shaft for a breakage (brushcutter) Check the belt for tension, correct fitting or damage (powercutter)



c. Drive shaft or belt


Check the gearbox input shaft and clutch drum thread for damage

• Drive shaft snaps due to the blade hitting a hard object or the blade was unbalanced and weakened the drive shaft through time until snapping occurs

• Drive shaft damaged due to incorrect starting procedure – foot on the tube – which could bend the drive shaft and eventually cause it to break

• Splines damaged at the clutch drum or gearbox end (clutch drum end could also be threaded and these threads may be stripped)

Supporting evidence

Action




56

Troubleshooting Practical – Drive Systems 2. Cutting equipment or attachment will not engage during full throttle c. Drive shaft or belt


c. Drive shaft or belt

• Fit a damaged drive shaft (broken or stripped splines) • Fit an oversized belt to simulate a stretched belt

Set-up options


57

Troubleshooting Theory – Drive Systems 2. Cutting equipment or attachment will not engage during full throttle d. Brake band

Check the brake band is not engaged or hindering the clutch



d. Brake band (chainsaw)


If engaged and the clutch was slipping, check the clutch drum bearing. Check the chain brake spring and band for wear

• Brake band engaged constantly due to a weak knee joint. Smoke from the clutch (slipping) will be visible if the engine is forced to run with the brake band engaged. Check the brake band for wear (thinnest part no less than 0.8 mm)

• Using the upper quadrant of the guide bar nose which causes kickback

Supporting evidence

Action




58

Troubleshooting Practical – Drive Systems 2. Cutting equipment or attachment will not engage during full throttle d. Brake band


d. Brake band (chainsaw)

• Fit a damaged or weak knee joint to ensure the chain brake engages constantly

Set-up options


59

Troubleshooting Theory – Drive Systems 2. Cutting equipment or attachment will not engage during full throttle e. Rim sprocket

Make sure the chain is fitted correctly into the rim sprocket



e. Rim sprocket

Engine reaches full RPM and the attachment engages slightly but when placed into wood it does not engage

Check the clutch drum splines

• Check that the chain drive links are correctly fitted into the rim sprocket

Check the chain drive links and clutch drum splines for excessive wear if the rim sprocket is worn

Supporting evidence

Action




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Troubleshooting Practical – Drive Systems 2. Cutting equipment or attachment will not engage during full throttle e. Rim sprocket


e. Rim sprocket

• Fit a chain deliberately off the rim sprocket • Fit a badly worn rim sprocket and chain with worn drive

links to show slippage whilst cutting

Set-up options


61

Troubleshooting Theory – Lubrication (Chainsaws) The lubrication system refers to the chainsaw cutting equipment oiling system and includes the following components: • Oil pump • Worm gear (oil drive wheel) • Oil hose and pickup • Oil tank, tank cap and breather • Guide bar *Make sure good quality chain oil is being used 1. Oiling problem – symptoms covered include:

• A chainsaw not oiling (guide bar on or off)

• A chainsaw not oiling enough (guide bar on)

• A chainsaw is oiling intermittently (guide bar on or off)

• A chainsaw oiling only when guide bar is off

• A chainsaw oils at idle when it should not (*Clutch or clutch drum problem)

• A chainsaw leaks large amounts of oil from the tank after use (guide bar on or off)

63

Troubleshooting Theory – Lubrication (Chainsaws)

1. Oiling problem a. Oil pump

Adjust oil pump flow higher (if applicable) and try again. If the problem persists, check the worm gear next before taking the oil pump apart. If the oil pump requires disassembly, make sure all o’rings are correctly fitted (if applicable to the oil pump type)

1. Oiling problem Check basics first (Section 1: Basics)

a. Oil pump

No or very little oil is being pumped when engine is revved

If the oil pump plunger is damaged check the worm gear. In all cases check the chain for damage

• If the pump plunger cannot be easily turned using your thumb, take the oil pump apart to check why it is tight. Dirt build up is most likely the cause

• The oil pump plunger shaft could be seized or partially seized due to dirt and not turn sufficiently to pump enough oil to the guide bar

• If the pump plunger gear turns freely on the shaft, check that the holding screw is not stripped. Also check the pump plunger gear pin for wear or damage

• Check that all the oil channels are free of dirt • If the pump is adjustable, this should be set according to

the guide bar length or type of wood being cut

Supporting evidence

Action




64


1. Oiling problem b. Worm gear (Oil drive wheel)

Inspect the worm gear for damage (stripped threads)


b. Worm gear

No oiling when engine is revved or oils at idle (clutch problem)

If the worm gear is damaged, check the oil pump plunger. In all cases check the chain for damage

• The worm gear will strip if the oil pump plunger is seized. This is normally due to dirt build up around the oil pump area

• The worm gear could also be damaged if the clutch drum is not aligned with the worm gear correctly

• The worm gear is normally made from a soft material that allows it to be damaged first should there be a problem. This is intended to save the more expensive oil pump from damage

Supporting evidence

Action




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1. Oiling problem c. Oil hose & pick-up

Remove the bar plate and check the hose for holes, correct fitting or other damage and check the pickup for blockage


c. Oil hose & pick-up

No or very little oil is being pumped when engine is revved

In all cases check the chain for damage

• Check the oil hose for damage and for correct fitting so that it seals against the crankcase correctly

• Check the pickup for dirt blockage from the tank • Check for holes in the oil hose

Supporting evidence

Action




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1. Oiling problem d. Tank cap or breather

Check the tank breather system for functionality


d. Tank cap or breather

Oil comes out for a short while when engine is revved, then stops. Oil seeps out after the engine is switched off.


• Make sure the tank cap threads are not damaged and it seals correctly when fitted

• Check the tank breather functionality and check for blockage form dirt. (Pressure testing the oil tank will indicate correct functionality)

Supporting evidence

Action




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1. Oiling problem e. Guide Bar

Check the guide bar oil holes for correct alignment or blockage


e. Guide bar

Oil comes out under the clutch cover when engine is revved but none or very little gets on the guide bar and chain


• Check that the guide bar oil holes lined up correctly with the oil channel in the crankcase

• Check the guide bar oil holes are free of dirt

Supporting evidence

Action




68

Troubleshooting Practical – Lubrication (Chainsaws)

1. Oiling problem All symptoms and components covered

1. Oiling problem

All components covered

Oil Pump • Fix the oil pump plunger shaft in place with Loctite to

simulate a seizure • Remove the pump plunger gear holding screw • Block the oil channels with some cloth

Worm Gear • Fit a stripped worm gear

Oil Hose & Pick Up • Block the oil pick up or hose with some cloth • Make a hole in the oil hose

Tank cap or breather

• Block the breather with varnish

Guide Bar • Block the guide bar oilier holes

Set-up options


69

Troubleshooting Theory – Cutting Equipment Cutting equipment troubleshooting often solves engine “power” and “performance” complaints. How well an engine performs is very often dependant on how well the cutting equipment is used and maintained. Individual engine component failures are sometimes a direct result from poor cutting equipment maintenance or use. The following will be covered in this section: 1. Chainsaw25 guide bar and chain

2. Cutting equipment – general

• Powercutter blades

• Brushcutter grass blades

• Clearing saw blades

• Brushcutter trimmy heads

• Hedgetrimmer blades

1. Guide bar & Chain The following common symptoms will be covered for guide bar & chain:

a. Chain will not turn around the guide bar or the chain wobbles in the guide bar groove

b. Cutting problems - Doesn’t cut, cuts slowly, cut is too aggressive or cuts skew

c. Chain will not turn around the guide bar or the chain comes off the guide bar

d. (Guide bar and chain shows signs of excessive wear)

e. Guide bar rails chipped or sprocket nose has collapsedChain slips in the cut

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Troubleshooting Theory – Cutting Equipment

1. Guide bar & Chain

Symptom Possible primary fault Action

Possible

secondary effects

a. Chain will not turn around

the guide bar or the chain wobbles in the guide bar groove

Wrong bar & chain combination

Make sure the chain pitch and chain gauge match the guide bar pitch and gauge

Check the rim sprocket and guide bar nose sprocket for wear

b. Cutting problems –

Doesn’t cut, cuts slowly, cut is too aggressive or cuts skew

Incorrect chain maintenance

Check the chain is correctly filed & check the tie straps for wear

Check the guide bar rails and sprocket nose for damage

c. Chain will not turn around

the guide bar or the chain comes off the bar

Incorrect chain tension

Check the chain tension is correct – Not too loose or too tight (Running a chain with incorrect tension will result in excessive wear on the chain and guide bar) Note* A too tight chain tension will also cause a lower no-load speed RPM reading on the tachometer. As soon as the chain heats up it will expand and this would result in the RPM increasing again. If the RPM increases too much, engine damage could occur.

Check the guide bar rails and nose for damage

d. Guide bar rails are

chipped or the sprocket nose has collapsed

Lack of bar maintenance

Make sure the bar rails are correctly dressed and the sprocket nose is sufficiently lubricated (greased)

Check the chain for stretch and the tie straps for wear

e. Chain slips in the cut

Worn rim sprocket

Check the rim sprocket for wear

Check the chain drive links and rim sprocket for wear

f. Guide bar worn and

shows signs of heat (bluing) and chain rivet joints are tight

Lubrication

Make sure there is enough chain oil reaching the guide bar and chain. Good quality oil is also important.

Check rim sprocket for wear

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1. Guide bar & Chain Effects of the Primary Fault

Possible primary fault Effects of the Primary Fault

Wrong bar & chain combination

• There are basically nine common possible guide bar & chain

combinations found for handheld chainsaws. These are:

Pitch: .325” 3/8” .404” Gauge: .050” .058” .063” It is important to match the guide bar combination to the chain.

Example: If the guide bar is a 3/8” x .058” combination, the chain must be

the same.

• The rim sprocket must also be the same pitch as the chain used.

Incorrect chain maintenance

• Incorrectly filed chains or dull chains are the single most

common cause of power and performance complaints. This can result in - engine overheating, overloading, air filter blockages, chain and guide bar damage, piston & cylinder scuffing

• A dull chain will not perform well in the cut and leads to the user

trying to force the cut which results in the chain jamming or the engine cutting out. This results in unnecessary wear or damage on the chain, guide bar and engine components

• A chain sharpened with a hook or backslope will be very

aggressive in the cut and is unsafe. This increases vibration levels and could result in power unit damage

• Cutters that are sharpened at different lengths will result in the

chain cutting skew

• Too low depth gauges results in an aggressive cut and increased vibrations

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1. Guide bar & Chain Effects of the Primary Fault

Possible primary fault Effects of the Primary Fault

Incorrect chain tension

• A too tight chain tension will result in the chain not turning

around the bar correctly at full RPM and will place unnecessary strain the engine. Tie strap wear will accelerate

• A too loose chain tension will result in damage to the guide bar

rails, chain tie straps and will increase the risk of the chain derailing – which is extremely unsafe

• The increase in tie strap wear due to incorrectly tensioned

chains, eventually leads to chain snapping

Note* Never tension a warm / hot chain. Wait until it cools first.

Lack of bar maintenance

• Guide bar rails do wear through normal use. When this wear

occurs, the rails peen and form burrs. These burrs need to be removed using a flat file (dress the rails) to avoid the burrs breaking off and causing rail chipping

• If the rails are worn excessively, the result will be that the chain

drive links will bottom out in the bar groove, making them flat. The chain and the rim sprocket will be damaged

• Bar rails worn excessively or unevenly are probably a result of

forcing a dull chain to cut or twisting the bar in the cut to straighten a skew cutting chain

Note* Never fit a new chain onto a worn guide bar

Worn rim sprocket

• A worn rim sprocket will not have sufficient engagement area to

drive the chain correctly and will result in the chain slipping in the cut

• If a chain is stretched out of pitch due to lack of lubrication or

incorrectly maintained, it will damage the rim sprocket (and guide bar nose sprocket) because they will not mesh. Shortening a stretched chain is not a solution to overcome the tensioning system. If a stretched chain is fitted onto a new guide bar or rim sprocket, they will immediately take the same wear pattern and this results in a waste of money

Note* Never fit a new chain onto a worn rim sprocket and visa versa

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2. Cutting equipment – General

• Powercutter blades

• Brushcutter grass blades

• Clearing saw blades

• Brushcutter trimmy heads

• Hedgetrimmer blades The following common symptoms will be covered for Cutting equipment - general:

a. Increased vibration levels felt

b. Not cutting correctly

c. Poor engine power & performance (no engine fault)

d. Blades jammed (hedgetrimmer)

74

Troubleshooting Theory – Cutting Equipment 2. Cutting Equipment - General

Symptom Possible primary fault Action

Possible

secondary effects

a. Increased vibration levels

felt

Blades unbalanced

Check if the blade is fitted correctly. If blade is found to be unbalanced, remove material where necessary to rectify the problem to rebalance.

Check for damage to the drive system

b. Not cutting correctly

(engine labouring)

Dull blades

Sharpen the blade ensuring it is balanced before fitting / using

Check for damage to the drive system

c. Poor engine power &

performance (trimmer)

Trimmer line too long

Adjust the trimmy line to the correct recommended length according to the type of trimmy head used

Carbon build up in the engine is possible if too long trimmy line is used for a long period

d. Blades jammed

(hedgetrimmer)

Blades have hit a hard object

Check the blade for damage from hitting a foreign object. Make sure the blade bolts are not over tightened

Check for damage to the gearbox and drive system

75


2. Cutting Equipment - General Possible causes of the Primary Fault

Possible primary fault Possible causes of the Primary Fault

Blades unbalanced

• Incorrectly fitted blades i.e. incorrect or no spacer used (if

applicable).

• Normal use or hitting a hard object causing the blade to bend and become unbalanced

Dull blades

• Through normal use or cutting abrasive material that is not

intended. i.e. Hitting the ground

Blades have hit a hard object

• Hitting a hard object can cause the blade(s) to peen and jam

77

Module 2 – Maintenance Introduction Correct maintenance practices will result in lower engine running costs and will help to identify small problems before they become large expensive problems. This practice is commonly known as Preventative Maintenance. Preventative maintenance is not a repair process and if done regularly, should offer a longer economical lifetime for the engine. The economical lifetime of an engine is normally referred to as the number of machine hours that an engine remains cost effective to maintain and run. Once the economical lifetime of an engine is passed, it should be replaced to avoid imminent engine failure and expensive repair costs. It is certainly possible to keep repairing an engine after the economical lifetime has been reached however the money spent, in a short time, would easily pay for a new one. Various preventative maintenance components should be checked or replaced at certain intervals of use. These intervals listed are a guideline and are as follows (mainly suited for professional users):

• Daily (after each use)

• 25 Hours (or weekly for professional users)

• 100 Hours (or monthly for professional users)

• 300 Hours (or after 3 months for professional users)

• 600 Hours (or after 6 months for professional users)

(Repeat the cycle)

78

Maintenance Theory Preventative Maintenance Checklist Check Replace Comments

Daily

Cutting equipment Air filter Safety equipment

As necessary

Daily maintenance includes cleaning the unit and performing a complete visual check. Note any damage or missing parts

25 Hrs

(Weekly)

Daily service + Fuel filter Spark plug Spark arrestor screen Gearbox for grease Starter rope for fraying Carburetor settings

As necessary

Clean behind the bar plate on chainsaws particularly around the oil pump area

100 Hrs (Monthly)

25 Hrs service + Piston ring (compression test) Decompression valve

Worm gear (chainsaw)

Fuel filter, Spark plug

Flush tanks out with clean fuel Clean cylinder fins

300 Hrs (3 Months)

100 Hrs service + Starter pulley and spring Muffler Oil pickup

Hoses and pipes for leaks

Piston ring (s) if worn (Cylinder & muffler gasket) Air filter Tank Breather

600 Hrs (6 Months)

300 Hrs service + Crankshaft big-end bearing Cylinder & piston + ring (s) Carburetor parts

Seals Main bearings Starter rope Gaskets

Worm gear

Repeat the cycle

79

Maintenance Theory

Worn Parts Identification & Analysis Identifying when parts are worn and replacing them timeously will save downtime and prevent further, larger problems from developing. This equates to cost savings for the customer. Most worn components can identified using the naked eye coupled with some experience however some cases require the wear limits information to determine if a component is worn. The following components will be analysed in this section:

• Air filter

• Spark plug

• Cylinder, piston and piston ring(s)

• Carburetor needle, lever and diaphragms

• Starter rope, pulley and spring

• Main bearings & crankshaft big-end bearing

• Brake band (chainsaw)

• Oil pump, pump plunger and worm gear (chainsaw)

80

Maintenance Theory Air filter The air filter should be replaced if:

• It has been cleaned a number of times and the dirt remains embedded so that very little light can be seen through the filter.

• If it were damaged in any way that would

allow dirt particles to enter Note: * The air filter must be perfectly clean in order to tune an engine correctly - i.e. to perform all carburetor adjustments correctly Clogged Filter Air filter Maintenance

Various types of air filters require different maintenance systems. Fabric or felt filters, nylon filters and foam filters can all be cleaned with soap and (warm) water then rinsed. Filters must be completely dry before re-fitting to the machine. Fuel, fuel mix or kerosene can also be used to clean these filters however soap and water is a cheaper option. Make sure to re-oil foam filters if required but take care not to apply too much as this would choke the engine. Fabric or felt filters can also be coated in special filter oil if the conditions are very dry and dusty. This will prolong the air filter effectiveness and result in slower component wear. Once again make sure not to apply too much as it will choke the engine. Compressed air or stiff bristled brushes should not be used to clean air filters as these can cause damage to the filter fabric. Note: * An air filter that is used for a prolonged period of time can never be completely cleaned,

therefore all air filters must be replaced at regular intervals. Damaged air filters must always be replaced.

81

Maintenance Theory

Spark Plug The spark plug gap should be checked and set to 0.5mm The spark plug should be replaced if:

• The electrode shows signs of wear / burning

• There is excessive carbon build up around the electrode

• The threads are damaged

• When it has completed approximately 100 Hours

Examining a used spark plug can also be very useful in giving an indication of how an engine is running. Examples: 1) A tan coloured plug means that the engine is running

normal and the air/fuel mixture is correct.

. 2) A plug worn out from being used for too long will show

the centre electrode rounded and the top electrode worn thin. A spark plug that is worn takes a lot more voltage to fire and causes poor engine running.

3) A black coloured (porcelain) plug is normally a result of

carbon deposits due to a too rich mixture, blocked air filter or excessive idling.

82

Maintenance Theory 4) A plug with a white coloured porcelain area indicates an

engine overheating / over revving.

Possible causes:

• Incorrect spark plug (too hot heat range) • Low octane fuel • Timing is not correct – check flywheel key • Cooling problems (dirty cylinder fins) • Carburetor air/fuel mixture is too lean (too much air) • Leaking crankshaft seals

5) A too rich fuel mix or carburetor setting can cause a plug to

carbon up. A carbon bead can lodge between the electrodes causing a misfire as the spark is thrown off course.

Cylinder, piston and piston ring(s) The piston failure analysis guide will show what a normally worn piston looks like and assist you to identify the causes of piston failures. Adhere to the wear limits to decide on replacement. The wear limits are as follows:

• Piston ring gap – not more than 1 mm

• Piston against cylinder (Cylinder bore wear) – not more than 0.1 mm

• Piston ring groove – not more than 0.15 mm clearance. Measured between the top of the

piston ring and the groove at the front (exhaust port) of the piston.

83

Maintenance Theory

Carburetor needle, lever and diaphragms Carburetor components do wear under normal working conditions however there are various situations that will accelerate this wear.

These include:

• Poor cutting equipment maintenance (Increased engine vibrations) • Ineffective fuel filter • Poor fuel quality • Playing with the throttle unnecessarily • Diaphragms can also go hard if the engine has been standing for a period of time without use

– this renders them ineffective

The needle, lever and diaphragms can normally be visually inspected for wear.

Examples of worn carburetor components: Needle – new and worn

Diaphragm – worn Lever – worn

84

Maintenance Theory

Starter rope, pulley and spring The starter rope and pulley should be visually inspected for wear.

The starter spring should be inspected if the rope does not fully retract.

Note the following:

• If possible re-tension the spring however take care not over tension. The pulley should have at

least a ½ turn extra after the rope is fully extracted • If the spring is tensioned correctly (allowing the ½ turn extra) and the rope is still not retracting

fully, it is possible to shorten the rope slightly until the correct tension is achieved. The rope should not be too short obviously. Your common judgment must determine if the spring should be replaced.

Main bearings and crankshaft big-end bearing If the main bearings felt to be rough or if there is movement between the inner and outer race, they are worn and should be replaced. If the conrod has up and down movement at the big end area, it indicates a worn bearing. This bearing is not replaceable and would require a new crankshaft to be fitted.

Note: * If an engine has approximately 800–1000 hours running time and a new cylinder & piston is being fitted, it should be considered that the crankshaft (if it is the original crankshaft) could be sufficiently worn to not withstand the new compression and could collapse after a short time.

Safety Equipment & Brake band

All safety equipment must be replaced if they are damaged, not functioning or missing. The brake band should be inspected regularly and replaced id the thinnest part is less than 0.8 mm. Oil pump, pump plunger and worm gear (chainsaw) Although oil pumps and worm gears do wear through normal use, the main cause for accelerated oil pump and component wear is dirt contamination. This includes the plunger gear holding screw and pin. The worm gear is normally manufactured from a soft material allowing it to be damaged first thus protecting the more expensive oil pump.

Most modern saws have the worm gear being driven by the clutch drum (this means no oiling at idle) The worm gear then drives the pump plunger gear. The rotating pump plunger then acts a piston and scoop, located in the oil pump housing. This constant piston movement in the housing causes wear, resulting in cavitations and therefore limited or no oil being pumped.

85

Maintenance Theory

P.D.I and Basic Service Guideline P.D.I (Pre-delivery inspection) A correctly performed P.D.I ultimately results in a satisfied customer receiving a product in perfect working order. A P.D.I performed incorrectly greatly increases the risk of embarrassing comebacks, customer dissatisfaction as well as unnecessary warranty claims. P.D.I procedures do vary from market to market however the same basic principles should apply. So without delving into model specific details, the following guidelines should be considered when performing a full and correct P.D.I:

Handheld Products 1) Box / Carton

• The box / carton is in good order should the customer request it. • The owner’s manual, warranty registration forms, etc, are present. • All tools (combi tool, allen keys, etc) that accompany the product are present. • All the relevant cutting equipment and their protective covers are present. • Other accessories that accompany the product are present i.e. Harness for brushcutters, etc.

2) Visual check

• Check the product exterior for visible cracks or damage. 3) Engine component checks (stop switch off)

• Remove and check the sparkplug gap (0.5mm). • Check the air filter for correct type (felt, nylon, foam, etc) and if it is a two-piece make sure it is

sealed correctly. Remember to engage the choke first before removing the air filter. Make sure the oiled foam type filters are in fact correctly oiled.

• Check the carburetor attachment bolts for the correct tightness. • Check that the stop switch lead is properly connected. • Check the exhaust bolts and the exhaust bracket bolts (if fitted) for correct tightness. Check the

spark arrestor is in place (if fitted). • Check the cylinder head bolts for correct tightness.

4) Starter and ignition module checks

• Remove the starter and check the rope/spring for correct tension. Pull the rope out about 10 cm then release. The starter handle should “snap” back into place.

• Make sure the starter pawls swing freely and the pawl springs don’t jam. • Check the ignition module gap against the flywheel (0.3mm). (Air gap tool - P/N 502 20 20 01). • Reassemble the starter, place the stop switch on and check for spark.

Note: Some products require the clutch cover to be removed when checking the ignition module air gap.

86

Maintenance Theory P.D.I (Pre-delivery inspection) 5) Drive system

• Grease the clutch drum bearing (if applicable). • Check the correct drive sprocket is fitted (chain saws – if applicable) • Check for grease in the gearboxes (brushcutters & hedgetrimmers - do not overfill!!) • Fit the applicable cutting equipment (correct chain tension for chain saws and polepruners &

correct belt tension for powercutters)

6) Running

• Check that the fuel filter is correctly fitted to the fuel pipe. • Fill with known, good fuel mix (and chain oil on those that require it). • Start the engine (cold start using choke) and allow a minute of idling to warm the engine. • Check for engine throttle response from idle to no-load rpm. Adjust the carburetor setting

screws if required. 7) Final check and running-in

• All safety equipment should be checked for functionality • Chain oiling should be checked and adjusted according to bar length and cutting application

(chain saws & polepruners). • Tighten all visible screws to the correct specifications • Perform the final carburetor adjustments • Wipe the product clean fit all cutting equipment protective covers (if applicable) and the product

should be ready for handover. Note* It is recommended to adjust all products 500–700 rpm below the recommended no-load speed for the fist 3-5 hours of use. This allows the engine to run slightly richer for the run-in period, which ensures maximum lubrication to the engine working parts.

87

Maintenance Theory

P.D.I and Basic Service Guideline Basic Service Guideline A basic service, by definition, is a maintenance procedure and not a repair. This means that the product should be in running order. This procedure may vary from market to market however the same end result should be achieved which is to make sure the product is returned to it’s original performance and is kept in a good serviceable condition. The 100 hrs service is used as a base for the following recommended guidelines when performing a basic service on a handheld product:

• Inspect the cutting equipment for signs of damage or misuse. Note any findings. • Sharpen and maintain the cutting equipment if necessary. • Clean the outside of the product (if necessary) in order to perform a complete visual check

noting any damage or missing parts. • Pull the starter rope to check the compression or use a compression tester. This will determine

if the piston ring(s) need replacing. • Remove the exhaust and check for carbon build-up in the exhaust, around the exhaust cylinder

port and on top of the piston crown. All carbon should be removed which will involve removing the cylinder if carbon is present on the piston crown.

• Clean or replace the spark arrestor screen (if fitted) • Clean the cylinder cooling fins. • Clean the starter grill. • Clean the flywheel fins and the crankcase area around the flywheel. • Clean around the carburetor. • Clean behind the bar plate particularly around the oil pump area (chain saws) • Clean the air filter (replace if necessary) • Check the starter rope for fraying or damage. • Check the starter spring for correct tension. • Check the drive sprocket for wear (chain saws & polepruners) • Check the oilier gear / worm gear for wear • Check the gearbox for wear and grease (brushcutters & hedgetrimmers) • Replace the spark plug • Replace the fuel filter • Tighten all screws to the correct specifications • Reassemble the cutting equipment • Check all safety features for functionality • Check that the engine starts easily and adjust the carburetor as required • Check the cutting equipment oiling function (chain saws & polepruners)

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Training “Tool-Box” List of suggested training material items (props) to use for the practical training – Note * this is product specific • Blocked fuel filter • Blocked air filter • Worn or stretched clutch springs • Clutch with shoes seized onto the spyder • Stripped worm gear • Worn carburetor parts i.e. lever, needle, diaphragms, choke shaft, throttle shaft • Worn piston • Worn piston ring (s) • Worn cylinder • Piston with stuck ring (s) • Seized cylinder and piston • Crankshaft with seized big-end bearing • Seized or worn main bearings • Malfunctioning spark plug • Flywheel with a sheared key • Blocked muffler / spark arrestor screen • Gearbox with stripped gears • Worn chain brake knee joint • Worn brake band • Badly maintained chain • Badly maintained guide bar • Worn rim sprocket • Worn clutch drum • Broken brushcutter drive shaft • Fuel hose with a hole • Manifold with a hole or crack • Frayed starter rope • Worn or weak starter spring • Carboned-up decompression valve Most of these items are easily located either in your own workshop or at a dealer. You should try collecting and building up a “Tool Box” of items such as these to assist with your practical training. It is of course better seeing the real part instead of pictures!

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Tips for Practical Examination marking Examination marking suggestions: Hand the student a product that has been set-up to simulate a known symptom. The student should then be checked on the following: 1. Check the symptom analysis and if the correct symptom is found

2. Check for correct possible diagnosis

3. Check the time taken to solve and repair the fault (use flat rates if required)

4. Note that the correct repair technique and tools are used

5. Acquire a list of possible realistic causes from the student

6. Ask for possible preventative maintenance solutions of the cause(s) (if applicable) Set-up suggestions for Basic Checks Build-in the following faults to test the “basics” knowledge: • Fuel filter blockage – coat the fuel filter with clear varnish • Carburetor settings – turn the adjustment screws out of normal • Air filter blockage – use an already blocked air filter or cover the inlet, almost completely, with

duct tape (some air should be allowed to enter) • Spark – Close the spark plug gap, increase the CD / flywheel gap • Muffler spark arrestor screen – Block the screen with duct tape • Hoses and manifold – make a small hole in the hoses or manifold with a screwdriver

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Examination

This serves as both the pre-test for RPL candidates and forms part of the final written examination after the course. Multiple Choice – Note * Marks will be deducted for incorrect choices Total 100 Marks 1. Troubleshooting - General (4 marks) What benefits does an effective troubleshooting process offer? a) Fast and efficient repair x b) Less wear on workshop tools c) Increased customer satisfaction x d) Decreased warranty claims x e) Increased spare parts sales f) Maximised workshop profitability x 2. Troubleshooting - General (5 marks) Which of the below statements best describes what Troubleshooting consists of? a) Identifying and being able to diagnose various symptoms efficiently x b) Establishing which special tools best suit the repair required c) Identifying the possible primary fault of a symptom x d) What initial actions should be taken to verify a symptom suspicion x e) Perfects the process-of-elimination approach when repairing a fault f) Identifying possible secondary components that might be effected by the primary fault x g) Establishing the root cause of a fault and the preventative maintenance thereof x 3. Troubleshooting - General (3 marks) What is the first line of approach when presented with a troubleshooting situation? a) Gather all the facts (if possible) x b) Replace parts by process of elimination until the problem is resolved c) Use your senses to gather information x d) Strip the machine down as quickly as possible to find the cause e) Check the basics first x 4. Troubleshooting - Engine (5 marks) Which of the following form part of the Engine Basics troubleshooting procedures? a) Pull the starter rope to see if the engine turns over and if compression is adequate x b) Check the piston for carbon build-up or ring stick c) Check fuel for quantity and correct mix - recommend to replace with a known mix x d) Check the fuel filter for blockage x e) Check the carburetor diaphragms for wear f) Check the air filter for blockage x g) Check for spark x

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Examination 5. Troubleshooting - Engine (3 marks) Select from the list below what the possible, common, causes of Flooding could be? a) Overfilling the fuel tank b) Trying to start the engine with the stop switch in the off position x c) Blocked muffler d) Blocked air filter x e) Carburetor needle or the metering lever are worn or the lever is incorrectly adjusted x f) Air leak in the fuel hose 6. Troubleshooting - Engine (2 marks) What are the possible causes for an engine that is not starting where the primary fault has been identified as carburetor related? a) Sieves totally blocked with dirt x b) Worn impulse hose c) The fuel hose is partially blocked with dirt d) Diaphragms and gaskets fitted in the wrong sequence x 7. Troubleshooting - Engine (4 marks) A possible primary fault for an engine not starting could be an air leak or blockage of some sort. Which of the following would cause this statement to be true? a) Crankcase seals go hard and leak if the machine stands for a long period of time x b) Decompression valve could be damaged and leaking c) Muffler could be blocked due to carbon build-up x d) Gaskets could be blown and leak due to excessive engine heat x e) Hoses could perish and leak due to certain fuel types x 8. Troubleshooting - Engine (2 marks) What could cause a flywheel key to shear? a) Using a too long guide bar for the size of the machine b) The flywheel nut not tightened correctly x c) A foreign object jamming the flywheel fins while the engine is running x d) Continuously running an engine with a too small ignition gap setting 9. Troubleshooting - Engine (2 marks) If the fuel tank breather were blocked, what would the symptom most likely be? a) The engine won’t start b) Idling would be uneven and the engine would cut out after 5 - 10 minutes of running x c) The engine would not reach maximum RPM d) A lack of power would be experienced after a short engine running time x

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Examination 10. Troubleshooting - Engine (1 marks) True or False: If an engine is run with worn piston or ring(s) for a prolonged period of time, this will eventually lead to a crankshaft big-end failure. a) True b) False x 11. Troubleshooting - Engine (3 marks) A blocked muffler or spark arrester screen would show the following symptoms: a) Lack of power x b) Will not accelerate x c) Engine would backfire d) Engine could cut out if full throttle is applied continuously x e) Piston and cylinder seizure 12. Troubleshooting - Engine (1 mark) If scratches were found on the flywheel magnets, what would the cause most likely be? a) Dirt drawn in by the flywheel fins b) Using the flywheel removal tool incorrectly c) The ignition module coming loose x d) The air conductor breaking and jamming between the flywheel and ignition module 13. Troubleshooting - Engine (3 marks) What are the possible, common, causes of a piston seizure? a) Incorrect fuel mixture x b) Worn carburetor diaphragms c) Partially blocked air filter d) Incorrectly adjusted carburetor x e) Maintaining maximum RPM for an extended period of time – over revving x 14. Troubleshooting - Engine (3 marks) What are the possible secondary components effected by a cylinder & piston seizure? a) Check main bearings x b) Check carburetor diaphragms c) Check crankshaft big-end bearing x d) Seals (recommended to change seals) x e) Check clutch and clutch drum

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Examination 15. Troubleshooting - Drive Systems (4 marks) What would cause the cutting equipment to be constantly engaged? a) Worn or broken clutch springs x b) Incorrect cutting attachment used c) Dirt build-up between the clutch shoes and clutch drum x d) Seized clutch drum bearing x e) High speed carburetor screw closed too much f) Carburetor idle adjustment is set too high x 16. Troubleshooting - Drive Systems (3 marks) What would cause the cutting equipment not to engage? a) Clutch shoes sticking x b) Idling set too low c) Gearbox gears damaged x d) Worn clutch springs e) Drive shaft or belts damaged / snapped x 17. Troubleshooting - Drive Systems (2 marks) If smoke was found to be emanating from clutch cover area, the possible causes are: a) Seized clutch drum bearing b) Brake band engaged while revving (chainsaws) x c) Worn clutch drum d) Cutting equipment jammed while revving x 18. Troubleshooting - Lubrication Systems (Chainsaws) (1 mark) What would the most likely cause be if a symptom shows intermittent oiling during use and excessive oil leakage after the engine is switched off? a) Damaged oil pump plunger b) Warped oil pump housing c) Blocked oil tank breather x d) Clutch drum / worm gear engagement problem 19. Troubleshooting - Lubrication Systems (Chainsaws) (1 mark) True or False: The worm gear is usually made from a softer material than the plunger gear? a) True x b) False

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Examination 20. Troubleshooting - Lubrication Systems (Chainsaws) (1 mark) The most likely cause of worm gear damage (stripped threads) is usually: a) Too high RPM b) Worn clutch drum c) Seized clutch drum bearing d) Seized plunger gear due to dirt build up x 21. Troubleshooting - Lubrication Systems (Chainsaws) (4 marks) Why is the oil pump adjustable on most Husqvarna chainsaw models? a) Due to species of wood x b) If the wood is wet or dry x c) The guide bar length x d) Type of chain oil used x 22. Troubleshooting - Cutting Equipment (Chainsaws) (1 mark) Chipped guide bar rails are a direct result of: a) Using a stretched chain to cut b) Incorrect bar maintenance – failure to dress the rails x c) Incorrect bar and chain combination d) Incorrect drive sprocket pitch 23. Troubleshooting - Cutting Equipment (Chainsaws) (1 mark) What would be the result if the left-hand cutters were sharpened at different lengths to the right-hand cutters? a) The chain would not cut b) The chain would only cut on the down stroke (pulling chain) c) The chain would cut screw x d) Kickback potential would increase 24. Troubleshooting - Cutting Equipment (Chainsaws) (3 marks) A too loose chain tension could result in: a) A decrease in engine RPM b) Accelerated tie strap wear x c) A risk of the chain-derailing x d) Oil pump damage e) Guide bar rail damage x

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Examination 25. Troubleshooting - Cutting Equipment (Chainsaws) (2 marks) A too tight chain tension could result in: a) A decrease in engine RPM x b) Accelerated tie strap wear x c) Chain snapping d) Bending of the guide bar 26. Troubleshooting - Cutting Equipment (Chainsaws) (3 marks) Which of the following statements are true? a) A stretched chain is mainly due to insufficient lubrication or forcing a dull chain to cut x b) A chain is more likely to snap on a longer guide bar than a shorter one c) A chain sharpened with a hook is more aggressive in the cut x d) A too low depth gauge setting will result in smoother cutting but will increase vibrations e) A new chain should not be fitted onto a worn rim sprocket and visa versa x 27. Troubleshooting - Cutting Equipment (Chainsaws) (2 marks) What would result in increased vibrations regarding the cutting chain? a) Forcing a chain to cut b) Cutters filed with either a hook or backslope x c) Worn tie straps d) Depth gauge setting too low x e) Oil pump adjusted too high (too much chain oil) 28. Troubleshooting - Cutting Equipment (Brushcutters) (3 marks) What are the possible causes of unbalanced blades? a) Too high engine RPM b) Incorrect sharpening x c) Hitting a hard object whilst cutting x d) Not rotating the blade e) Incorrectly fitted x 29. Maintenance - General (3 marks) What are the advantages of having a preventative maintenance system? a) Engine components tend to last longer x b) Results in overall lower engine running costs x c) The air filter or fuel filter never need to be changed d) Small problems can be corrected before they become large, expensive, problems x e) Eliminates emission levels

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Examination 30. Maintenance (5 marks) Daily maintenance comprises of the following checks: a) General cleaning of the unit x b) Perform a visual check of the unit and notice any damage x c) Check the piston ring(s) for wear d) Check and clean the air filter if necessary x e) Check the cutting equipment and sharpen if required x f) Remove the muffler and check for blockage g) Make sure all the safety equipment is functioning x 31. Maintenance (4 marks) What is true about air filter maintenance? a) All air filters can effectively be cleaned with soap and water x b) Oiling foam filters too much results in the engine being choked x c) Fabric or felt filters can be coated with special filter oil x d) Cleaning filters with compressed air or stiff bristled brushes prolongs their lifetime e) Damaged air filters should be replaced immediately x f) Correctly maintained air filters should never need to be replaced 32. Maintenance (1 mark) True or False: An air filter should be completely dry before reassembling. a) True x b) False 33. Maintenance (4 marks) When should it be considered time to replace a spark plug? a) When the HT lead is replaced b) When the electrode shows signs of wear / burning x c) If the spark plug cap is damaged d) When there is excessive carbon build up around the electrodes x e) When the threads are damaged x f) When it has completed approximately 100 Hours x 34. Maintenance (2 marks) What causes a spark plug to carbon up? a) If the engine idles for a prolonged period b) Incorrect carburetor settings x c) A too rich fuel mixture x d) If the carburetor diaphragms are worn

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Examination 35. Maintenance (1 mark) What are the wear limits of a piston ring gap, piston ring groove and piston against cylinder respectively? a) Piston ring gap 1mm, Piston ring groove 0.15mm and Piston against cylinder 0.1mm x b) Piston ring gap 0.1mm, Piston ring groove 0.15mm and Piston against cylinder 1mm c) Piston ring gap 1mm, Piston ring groove 0.5mm and Piston against cylinder 0.15mm 36. Maintenance (Chainsaws) (3 mark) What would accelerate the wear of carburetor components unnecessarily? a) Ineffective fuel filter x b) Throttling unnecessarily x c) Poor quality 2-stroke oil d) Poor cutting equipment maintenance x 37. Maintenance (Chainsaws) (1 mark) What is the wear limit of a brake band before is requires replacing? a) 1.0mm b) 0.6mm c) 0.8mm x 38. Maintenance (1 mark) True or False: A starter rope can be shortened and re-tensioned to accommodate a worn or weak starter spring? a) True x b) False 39. Maintenance (3 marks) What must be true in order to tune an engine correctly? a) The fuel filter must be new b) The air filter must be clean x c) The spark plug must be new d) The exhaust must not be blocked x e) The cylinder cover / air filter cover should be fitted x

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Troubleshooting Theory - Template Fill in your own symptoms based on local knowledge and experience. This is followed by the practical set-up of the product to replicate that symptom. Template:

Troubleshooting Theory – XXXX (fill in the area

concerned i.e. Engine)

1. Fill in the symptom (i.e. Engine not starting) a. Fill in the possible primary fault of the symptom (i.e. Air leak or blockage)

XXXX (Actions required to establish the symptom suspicion)

1. XXXX (Symptom) Check basics first (Section 1: Basics)

a. XXXXX (Primary fault)

XXXX (Supporting evidence for the primary fault)

XXXX – (List the secondary components effected if any)

• XXXX (List possible causes of the symptom) • XXXX • XXXX

Supporting evidence

Action




Instructor note: XXXX (Fill in any notes for the instructor if applicable)

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1. XXXX (Symptom)

a. XXXXX (Primary fault)

• XXXX (List possible set-up options to replicate the symptom) • XXXX • XXXX

Set-up options


Troubleshooting Practical - Template Fill in your own product set-up suggestion if symptoms are added based on local knowledge and experience. Template:

Troubleshooting Practical – XXXX (fill in the area

concerned i.e. Engine)

1. Fill in the symptom (i.e. Engine not starting) a. Fill in the possible primary fault of the symptom (i.e. Air leak or blockage)

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