CHAPTER 8

Vehicle Maintenance Inspection

Introduction

• Regular inspection of a vehicle helps ensure the safe and reliable operation of a vehicle.

• Types of inspections– Underhood inspection

– Exterior inspection

– Certain in-vehicle inspections

– Under-vehicle inspection

• Check fluid levels, lighting systems, etc.

• Faults or concerns should be noted for service or repair.

Underhood Inspection

• Performed at manufacturer’s recommended intervals and prior to long driving trips

• Component damage or failure is often caused by a lack of service or low fluid level.

Fluids

• Always use the recommended type and amount of fluid.

• The quality of fluid is important.– Nearly all fluids get old, wear out, and require

replacement.– There may be a change in color or consistency, a mix

of fluids, or change in smell.

Engine Oil (1 of 2)

• Level of oil in engine lubrication system is critical to its operation.– If too low, oil pump will

starve for oil.– If too high, oil will be

struck by the crankshaft, churning it into foam.

Engine Oil (2 of 2)

• Oil level should be checked periodically, usually at every fuel stop or two.

• When checking oil level, consider checking if it is time for an oil change.– The manufacturer will specify the vehicle’s oil-life

monitoring (OLM) system.

• Levels should be checked first.

• A low reading could indicate a seal or gasket is leaking or engine is burning oil.

Engine Coolant (1 of 3)

• Checked whenever the oil level is checked

• Engine cooling system depends on coolant to transfer excessive heat from engine to the radiator.

Engine Coolant (2 of 3)

• Some have a transparent reservoir marked with “hot” and “cold.”

• Some may have an overflow tank.

Engine Coolant (3 of 3)

• Low coolant levels can cause engine overheating.

• Coolant freezing point is also checked.

• Anti-freeze protection level is checked with an anti-freeze hydrometer. – A refractometer can also be used.

Brake and Clutch Fluid (1 of 3)

• A hydraulic braking system depends on brake fluid.

• Brake fluid should be checked whenever the oil level is checked, or monthly.– Check the color of the brake fluid.

Brake and Clutch Fluid (2 of 3)

• Most brake fluids are hygroscopic.

• Check the fluid with either a brake fluid tester or brake fluid test strips.

Brake and Clutch Fluid (3 of 3)

• Manual transmissions have hydraulic clutch system. – Uses both master cylinder and brake fluid – The brake fluid reservoir also may supply the clutch

master cylinder.– The clutch may have a separate fluid reservoir.

Power Steering Fluid (1 of 2)

• Power for the power-assisted steering systems usually comes from an engine-driven hydraulic pump.– Some use an electrically driven pump.

Power Steering Fluid (2 of 2)

• The fluid level must be at proper level to avoid drawing air into hydraulic system and to prevent fluid overflow when engine is hot.

• The fluid can be checked with a dipstick connected to the filler cap.

• Also check the appearance of the fluid. – Dark or black fluid usually means fluid is old and

needs to be changed.

Automatic Transmission/Transaxle Fluid (1 of 3)

• Correct fluid level is critical to the effective and efficient operation of the transmission. – If level is too low, slipping and shift timing faults can

result.– If level is too high, transmission will churn and aerate.

• Fluid level is usually checked with a dipstick located under the hood.

Automatic Transmission/Transaxle Fluid (2 of 3)

• If adding transmission fluid, make sure to select the correct fluid.

• In a manual transmission/transaxle, low fluid levels result in early bearing failure.

Automatic Transmission/Transaxle Fluid (3 of 3)

• Vehicle must be level.– Usually accessed

through a fill plug on side of transmission/transaxle

– Carefully stick a finger in hole and bend finger down to feel level of fluid.

Diesel Exhaust Fluid

• Some late-model diesel-powered vehicles use diesel exhaust fluid (DEF), or AdBlue™.

• DEF is injected into exhaust stream to reduce oxides of nitrogen.

• DEF needs to be replenished periodically.

• Filler cap is often located under hood and may be colored blue.

• Do not put washer fluid in the DEF tank.

Windshield Washer Fluid (1 of 2)

• The washer system must be ready to work when the windshield is obstructed.

• The washer fluid reservoir is normally located under the hood of the vehicle.

Windshield Washer Fluid (2 of 2)

• Fluid should be checked when oil is changed.

• Use properly formulated and mixed washer fluid.

Engine Drive Belts (1 of 4)

• Operate various accessories on the engine

• These belts will wear along with associated idler and tensioner pulleys.

Engine Drive Belts (2 of 4)

• V-type belt – Sits inside a deep V-

shaped groove in the pulley

– The sides of the V-belt contact and wedge in the sides of the V in the pulley.

Engine Drive Belts (3 of 4)

• Serpentine-type belts– Have a flat profile with a

number of grooves running lengthwise along the belt

• Grooves are exact reverse of grooves in outer diameter of the pulleys.

• Check the drive belts whenever the hood is opened for service.

• Water pump is most important component driven by the belt.

Engine Drive Belts (4 of 4)

• The engine will quickly overheat if belt breaks or comes off.

• Vehicles using a serpentine belt also have a spring-operated tensioner and pulley.

• Stretchy belts or StretchFit™ belts– Don’t use a method for tensioning the belt– Stretchiness applies appropriate amount of tension to

the belt over its useful live.

Belts

• Belts should be checked for:– Cracks– Oil soaking– Glazing– Tears– Bottoming out

Hoses (1 of 2)

• At the radiator, there will be a large upper radiator hose and a large lower radiator hose.

• Smaller heater hoses run from engine block, manifold, or water pump to connections at heater assembly.

Hoses (2 of 2)

• Engine should be cool when inspecting hoses.– If hot, look for bulging in the hoses.

• One defective hose usually means other hose(s) may be deteriorating.– Check for any small hoses that may connect

components.

Changing the Air Filter

• Engine needs a free flow of clean air to operate correctly and with low emissions.– If the filter is not fitted correctly or sealed properly, air

can bypass the filter.

• The location of the filter will vary.

• While inspecting the air filter, check the air cleaner housing and duct work for cracks or holes.

Performing a Visual Inspection

• Vehicle should be checked for overall roadworthiness. – Owner may perform this inspection.

• Work in a systematic manner.– Use inspection sheet.– Inspect each vehicle in the same way.

Checking the Wiper Blades (1 of 2)

• Checked as part of the exterior inspection

• More than year old is ready for replacement

• Wiper blade and arm should be checked. – Should flex at the hinge and be held firmly against the

windshield by wiper arm spring– Check rear wiper blade in the same way.

Checking the Wiper Blades (2 of 2)

• Never operate the wipers when they are dry.

• Never bend the arms to make better contact with the windshield.

• Replace if it seems to have lost its spring tension.

Inspecting the Windshield

• Inspected during the wiper blade inspection

• Scratched, scored, or pitted glass will not wipe clean.

• Windshields may become etched or pitted, causing the wipers to function poorly.

• Some small chips or cracks can be repaired with special resin and tools. – Large chips or cracks larger than 3″ may be reason to

replace the windshield.

Inspecting the Interior and Exterior Lights

• The lighting system:– Allows the driver to see the road when driving at night

or in poor-visibility conditions– Signals to other drivers

• Check all interior lights.

• Check all exterior lights.

Inspecting the Tires (1 of 2)

• Tires are checked for: – Pressure– Wear patterns– Cuts– Tread depth

• Tire condition is one of the most important safety considerations.

Inspecting the Tires (2 of 2)

• Tires are inflated using pressurized air or nitrogen to support the weight of the vehicle. – Normal tire pressure varies.– Recommended tire pressures for vehicle are located

on the tire placard.– Maximum tire pressure on the tire sidewall is the

maximum pressure for that tire.– Never inflate the tire above the recommended

maximum pressure.

Checking the Brake Pedal

• Changes to how far pedal travels or to its resistance can be an indicator of problems. – Always check this before driving a vehicle in or out of

the shop.

• Listen for unusual noises.

Checking the Parking Brake

• The parking brake is used to hold the vehicle in position when parked.– Automatic transmission owners may not know brake

might not work at all until it is needed.

• The parking brake cable can freeze in the applied position in climates with below-freezing temperatures.

Checking the Instrument Panel Warning Lamps

• Warning lamps can indicate faults or proper operation with various systems.

• The warning lamps perform a self-check each time the ignition is switched on or the engine cranked. – Observe the action of the lights when operating the

vehicle to determine if additional services may be required.

Checking the Horn

• Usually operated by a relay or by vehicle body control module (BCM)

• There may be a single horn or a pair of horns.– With two horns, one will sound at a lower pitch than

the other.

• Horns are located at front of vehicle behind the grill or bumper.

• Easily checked before entering the shop

Under-Vehicle Inspections (1 of 9)

• Systematic visual inspections of all major vehicle systems

• Note any faults to discuss with supervisor.

• A good way to get a feel for the overall condition of the vehicle

Under-Vehicle Inspections (2 of 9)

• The steering area– Check for any excess movement in driveshaft

universal joints.– Look for any dents or bending of the shaft.

• The front-wheel drive axles– Includes the constant velocity joints and dust boots – Look for cracked, torn, or leaking boots.

Under-Vehicle Inspections (3 of 9)

• The engine area– Check for coolant, oil, and fuel leaks. – Look for torn or cracked motor mounts, coolant

hoses, and belts.

Under-Vehicle Inspections (4 of 9)

• The transmission area– Includes the transmission case, clutch housing,

external linkages, and wiring connectors – Check for fluid leaks, loose mounting bolts, and faults

or looseness in the clutch mechanism or shift linkage.

Under-Vehicle Inspections (5 of 9)

• The exhaust system– Clamps and bolts may need tightening on the exhaust

system or on the exhaust system-to-manifold bolts or gaskets.

– Check for signs of exhaust leaks, corrosion, or deterioration, including the exhaust hanger hardware.

– Check the condition of any heat shields.

Under-Vehicle Inspections (6 of 9)

• The parking brake cables– The cables are encased in a housing that attaches

the parking brake lever or pedal to the rear brakes. – Check for rusted, frozen, broken, or crushed cables.

Under-Vehicle Inspections (7 of 9)

• The driveshaft– Transmits power from the transmission to the rear

axle on rear-wheel drive vehicles – Check for any excess movement in driveshaft

universal joints. – Look for any dents or bending of the shaft.

Under-Vehicle Inspections (8 of 9)

• The differential, rear axle, and rear suspension area– The rear axle includes the differential and axle shafts.– Look for leaks around the differential and check the

rear shock absorbers, leaf springs, brake hoses, and lines.

Under-Vehicle Inspections (9 of 9)

• The fuel tank– Metal or plastic– The fuel tank must be secure and fuel lines inspected

for damage or abrasions.

Checking for Fluid Leaks (1 of 6)

• The service bay should be clean and dry.

• Distinctive colors, feels, and smells– Brake fluid

• Clear or light amber looking for DOT 3 and DOT 4• DOT 5 is usually purple.• Slightly slippery• Has an unpleasant, slightly acid-type smell

Checking for Fluid Leaks (2 of 6)

• Distinctive colors, feels, and smells (cont’d)– Automatic transmission fluid and some manual

transmission fluid• Normally reddish in color • Very slippery and oily• Has an oily smell

– Power steering fluid• Similar characteristics to automatic transmission

fluid

Checking for Fluid Leaks (3 of 6)

• Distinctive colors, feels, and smells (cont’d)– Coolant

• Normally green, orange, or yellow in color• Some use a coolant that is red or light red.• Slippery• Has a sweet smell like syrup

– Engine oil• Brown or black in color• Very slippery and a bit thick• Has an oily smell

Checking for Fluid Leaks (4 of 6)

• Distinctive colors, feels, and smells (cont’d)– Manual transmission fluid

• Light brown in color• Very slippery and thick like syrup• Has an oily smell

– Gasoline• Clear in color• Evaporates easily• Has a distinctive gas odor

Checking for Fluid Leaks (5 of 6)

• Distinctive colors, feels, and smells (cont’d)– Diesel

• Dirty clear in color• Thin• Has an oily smell

• Leaks will normally be more visible on a warmed-up vehicle.

• Ask customer if there are any unusual smells when the vehicle is first started.

Checking for Fluid Leaks (6 of 6)

• To check for leaks:– Drive the vehicle into a clean, well-lit work stall.– Ideally will have a lift– Use a flashlight to inspect underside of vehicle for any

drips or wet areas.– While engine runs, wait to see if anything drips.– Identify fluid that is leaking and where it is from. – Always look toward top of wet area.– A leak under pressure can be sprayed a good

distance from a small hole.

Summary (1 of 5)

• A check under the hood is important to the life and operation of the vehicle.

• Correct type and amount of fluid is important for reliable and safe operation of the vehicle

• Engine drive belts and coolant hoses should be inspected and replaced according to manufacturer’s service schedule.

Summary (2 of 5)

• The engine needs a free flow of clean air from the air filter in order to operate correctly.

• A periodic inspection of the vehicle’s exterior can prevent troubles that may cause safety or operational concerns.

• Once a month or prior to any long trip, a vehicle should be visually checked for overall roadworthiness.

Summary (3 of 5)

• The windshield wiper blades and arms are an important safety system on every vehicle.

• The windshield should be inspected during the wiper blade inspection process.

• The lighting system allows the driver to see when driving at night or in poor-visibility conditions and to signal to other drivers.

• The tires and their condition are one of the most important safety considerations on the vehicle.

Summary (4 of 5)

• Certain in-vehicle inspections and checks should be made as the vehicle is driven into the service bay.

• The technician should always check the brake pedal feel and travel before driving into or out of the shop.

• The parking brake should be checked as part of a routine safety or vehicle inspection.

Summary (5 of 5)

• The many instrument panel warning lamps can indicate faults with various systems on the vehicle.

• The horn can easily be checked before driving the vehicle into the shop.

• With the vehicle safely lifted on a hoist, an underbody inspection is a good way to get a feel for the overall condition of the vehicle.

Credits

• Unless otherwise indicated, all photographs and illustrations are under copyright of Jones & Bartlett Learning.