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SERVICE MANUAL SERVICE MANUAL SECTION AIR COMPRESSOR: BENDIX TU-FLO 501 Vendor: BENDIX Model: 2000 Model: 3000 Model: 4000 Model: 7000 Model: 8100 Model: 8200 Model: 8300 Vendor Code: 04SBA s04010, Formerly CTS-5145 03/31/1996 s04010 Copyright© 03/31/1996 Navistar, Inc.

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  • SERVICE MANUAL

    SERVICE MANUAL SECTION

    AIR COMPRESSOR: BENDIX TU-FLO 501

    Vendor: BENDIXModel: 2000Model: 3000Model: 4000Model: 7000Model: 8100Model: 8200Model: 8300

    Vendor Code: 04SBA

    s04010, Formerly CTS-5145

    03/31/1996

    s04010Copyright03/31/1996 Navistar, Inc.

  • AIR COMPRESSOR: BENDIX TU-FLO 501 i

    Table of Contents

    DESCRIPTION.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

    1. OPERATION.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.1. INTAKE AND COMPRESSION OF AIR (LOADED). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.2. NOT COMPRESSING AIR (UNLOADED). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

    2. LUBRICATION.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

    3. COOLING.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

    4. MAINTENANCE.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44.1. AIR STRAINER (FILTER). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44.2. POLYURETHANE SPONGE STRAINER (FIGURE 5 ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44.3. DRY ELEMENT PLEATED PAPER AIR STRAINER (FIGURE 6 ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44.4. COMPRESSORS WITH INTAKE ADAPTERS (FIGURE 7 ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54.5. EVERY 50,000 MILES (80,000 KM) OR 6 MONTHS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54.6. EVERY 200,000 MILES (322,000 KM) OR 24 MONTHS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54.7. OPERATION TESTS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54.8. AIR LEAKAGE TESTS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

    5. REMOVE.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

    6. DISASSEMBLE.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

    7. CLEAN AND INSPECT.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117.1. CYLINDER HEAD.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117.2. CRANKCASE.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .117.3. PISTONS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127.4. CRANKSHAFT.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137.5. END COVER.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137.6. CONNECTING ROD BEARINGS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

    8. REPAIR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148.1. DISCHARGE VALVES, VALVE STOPS AND SEATS (FIGURE 13 ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148.2. DISCHARGE VALVES LEAKAGE TEST.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148.3. INLET VALVES AND SEATS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

    9. REASSEMBLE.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

    10. TESTING.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

    11. TROUBLESHOOTING.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

    12. SPECIFICATIONS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2312.1. COMPRESSOR DATA.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2312.2. MEASUREMENTS.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2512.3. TORQUE CHART.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

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  • ii AIR COMPRESSOR: BENDIX TU-FLO 501

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 1

    DESCRIPTIONThe Tu-Flo 501 air compressor (Figure 1 ) is a two-cylinder, single stage, reciprocating piston type, with a rateddisplacement of 12 cubic feet of air per minute at 1250 RPM.

    Figure 1 Tu-Flo 501 Air Compressor

    The compressor is constructed of two major assemblies: the head and the crankcase. The head houses thedischarge valving and is installed on the upper portion of the crankcase. The crankcase is a one-piece castingcombining the cylinder block and crankcase. The upper portion of the casting houses the cylinder bores andinlet valving and the lower portion houses the crankshaft and main bearings.

    Two methods are employed for cooling the compressor during operation. The cylinder head is connected to theengines cooling system, while the cylinder bore portion of the crankcase has external fins for efficient cooling.

    All Tu-Flo 501 compressors utilize the engines oil pressure system to lubricate internal moving parts.

    1. OPERATIONThe compressor is driven by the engine and runs continuously while the engine is operating, but the actualcompression of air is controlled by the governor which, acting in conjunction with the unloading mechanismin the compressor, starts or stops the compression of air by loading or unloading the compressor when thepressure in the air brake system reaches the minimum or maximum air pressure levels.

    1.1. INTAKE AND COMPRESSION OF AIR (LOADED)

    During the downstroke of each piston, a slight vacuum is created between the top of the piston and thehead, causing the flat circular inlet valve to move up and off its seat. The flat discharge valve will remain onits seat. Air drawn through the intake port on the down stroke enters the cylinder above the piston throughthe inlet valve (Figure 2 ). As the piston starts the upward stroke, the air is being compressed. Air pressureon top of the inlet valve plus the force of its spring returns the inlet valve to its seat. The piston continues

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  • 2 AIR COMPRESSOR: BENDIX TU-FLO 501

    the upward stroke and compressed air then flows by the open discharge valve into the discharge line and onto the reservoirs (Figure 3 ).

    Figure 2 Intake and Compression of Air

    Figure 3 Compressed Air Flows to Reservoir

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 3

    1.2. NOT COMPRESSING AIR (UNLOADED)

    When the air pressure in the reservoir reaches the maximum setting of the governor, the governor allows airto pass from the reservoir into the cavity beneath the unloader pistons. This lifts the unloader piston andplungers. The plungers move up and hold the inlet valves off their seats (Figure 4 ).

    Figure 4 Not Compressing Air (Unloaded)

    With the inlet valves held off their seats by the unloader pistons and plungers, air is pumped back andforth between the two cylinders. When air is used from the reservoir and the pressure drops to the cut-insetting of the governor, the governor closes and exhausts the air from beneath the unloader pistons. Theunloader saddle spring forces the saddle, pistons and plungers down and the inlet valves return to theirseats. Compression is then resumed.

    2. LUBRICATIONThe Bendix Tu-Flo 501 air compressor is lubricated by the engine oil, therefore it is recommended that theengine oil be checked regularly and changed at proper intervals.

    3. COOLINGThe Bendix Tu-Flo 501 air compressor cylinder head is cooled by the engine cooling system, therefore it isrecommended that the cooling system be checked regularly.

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  • 4 AIR COMPRESSOR: BENDIX TU-FLO 501

    4. MAINTENANCE4.1. AIR STRAINER (FILTER)

    Refer to the Operators Manual for the interval that the air strainers (filters) should be cleaned or replaced.

    The operating conditions, experience and type of strainer used may designate more frequent service ofthe air strainers.

    4.2. POLYURETHANE SPONGE STRAINER (FIGURE 5 )

    Figure 5 Polyurethane Sponge Strainer

    Remove and wash all parts. The strainer element should be cleaned or replaced. If the element is cleaned, itshould be washed in a commercial solvent or a detergent and water solution. The element should be saturatedin clean engine oil, then squeezed dry before replacing it in the strainer. Be sure to replace the gasket ifentire strainer was removed from compressor intake.

    4.3. DRY ELEMENT PLEATED PAPER AIR STRAINER (FIGURE 6 )

    Figure 6 Dry Paper Strainer

    Remove spring clips from side of mounting baffle and remove cover. Replace pleated paper filter and reinstallcleaner cover making sure the filter is in position. Be sure to replace air strainer gasket if entire strainer isremoved from compressor intake.

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 5

    4.4. COMPRESSORS WITH INTAKE ADAPTERS (FIGURE 7 )

    Figure 7 Adapter to Engine Air Cleaner

    The compressor receives clean air from engine air cleaner. When the engine air cleaner is serviced or thefilter is changed, the intake adapter and hose should be inspected. Inspect connecting hoses for rupturesor loose connections. Replace hose if required or tighten connections if needed. If intake adapter is loose,remove it, clean strainer plate (if applicable) and replace adapter gasket. Then reinstall adapter; tightenall hose connections securely.

    4.5. EVERY 50,000 MILES (80,000 KM) OR 6 MONTHS

    Remove discharge head fittings and inspect the compressor discharge port and discharge line for excessivecarbon deposits. If excessive carbon is noted, the discharge line must be cleaned or replaced and compressorchecked more thoroughly, paying special attention to air induction system, oil supply and return system, andproper cooling. If necessary, repair or replace compressor. Check for proper belt pulley alignment and belttension. Adjust, if required, paying special attention not to overtighten belt tension. Check for noisy compressoroperation which could indicate a worn drive gear coupling or a loose pulley. Adjust and/or replace as required.

    Check all compressor mounting bolts; retighten evenly, if necessary. Check for leakage and proper unloadermechanism operation. Replace any defective parts.

    4.6. EVERY 200,000 MILES (322,000 KM) OR 24 MONTHS

    Perform a thorough inspection by disassembling the compressor. Clean and inspect all parts thoroughly;repair or replace all worn or damaged parts or replace compressor depending upon the results of inspectionand experience.

    CAUTION In the event it becomes necessary to drain the engine cooling system to prevent damagefrom freezing, be sure the cylinder head of the compressor is drained also.

    4.7. OPERATION TESTS

    Vehicles manufactured after the effective date of FMVSS 121, with the minimum required reservoir volume,must have a compressor capable of raising air system pressure from 85 to 100 psi in 25 seconds or less, withthe engine operating at maximum governed speed. The vehicle must be certified of this performance on newvehicles with all allowances for air systems with greater than minimum required reservoir volume.

    4.8. AIR LEAKAGE TESTS

    Air leakage past the discharge valves can be detected by removing the discharge line, applying air backthrough the discharge port and listening for air escaping. The discharge valves and the unloader piston

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  • 6 AIR COMPRESSOR: BENDIX TU-FLO 501

    can be checked for leakage by building up the air system until the governor cuts out, then stopping theengine. With the engine stopped, listen for air escaping at the air compressor intake. To pinpoint leakage ifnoted, apply a small amount of oil around the unloader pistons. If there is no leakage noted at the unloaderpistons, the discharge valves may be leaking. If it is not functioning as described or leakage is excessive,it is recommended that it be repaired or replaced.

    5. REMOVE

    WARNING When any component is serviced or removed from the air system, be sure to setthe parking brake and block the vehicle wheels to prevent it from moving while service is beingperformed.

    1. Drain air pressure from all reservoirs.

    2. Drain engine cooling system and cylinder head of compressor.

    3. Disconnect all air, water and oil lines leading to and from the compressor.

    4. Remove compressor mounting bolts and drive belts as required.

    5. Remove compressor from engine.

    6. Use suitable puller to remove pulley or gear from compressor crankshaft after removing crankshaft nut.

    7. Inspect pulley or gear and related parts for wear or damage. If any parts are found worn or damaged,they must be replaced.

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 7

    6. DISASSEMBLEBefore disassembling the compressor, the following parts should be marked for correct alignment atreassembly. Scribe mark front and rear end covers in relation to crankcase. Mark drive end of crankshaft.Mark cylinder head in relation to crankcase and mark base plate or base adapter (Figure 8 and Figure 9 ).

    Figure 8 Alignment Marks

    1. ALIGNMENT MARKS

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  • 8 AIR COMPRESSOR: BENDIX TU-FLO 501

    Figure 9 Exploded View

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 9

    1. CRANKSHAFT NUT2. ADAPTER COVER FLANGE WITH BEARING3. END COVER O-RING4. CRANKSHAFT BEARING5. CONNECTING ROD BOLT6. CONNECTING ROD BEARING7. CONNECTING ROD WITH CAP8. PISTON WITH PIN9. PISTON RING SET10. LOCK WRIST PIN WIRE11. PISTON WRIST PIN12. CYLINDER HEAD13. DISCHARGE VALVE SPRING14. DISCHARGE VALVE15. DISCHARGE VALVE SEAT16. CYLINDER HEAD GASKET17. INLET VALVE BUSHING18. INLET VALVE SEAT19. INLET VALVE SPRING20. INLET VALVE21. INLET VALVE STOP22. INLET VALVE GUIDE23. BACK-UP RING24. O-RING25. REAR COVER WITH BEARING26. THRUST WASHER27. AIR COMPRESSOR CRANKSHAFT28. AIR COMPRESSOR CRANKCASE29. CRANKCASE GASKET30. CRANKCASE COVER31. CRANKCASE COVER O-RING32. CRANKSHAFT BUSHING33. CRANKSHAFT KEY

    1. Remove all attachments such as governor, air strainer inlet fittings, discharge fittings and pipe plugs.

    2. Remove six cylinder head capscrews and tap the head with a soft mallet to break the gasket seal. Removehead and gasket.

    3. Remove inlet valve springs from the head, and inlet valves from their guides in the crankcase. Removeinlet valve guides from the valve seats on crankcase taking care not to damage seats.

    4. Scrape off gasket material from cylinder head and crankcase.

    5. Unscrew discharge valve seats from cylinder head and remove discharge valve and springs.

    6. To remove the discharge valve stops, support the machined surface of the cylinder head on an arbor pressbed and carefully press the stops from the top of the head and out the bottom. Be sure to allow sufficientclearance for the stops between the press bed and bottom of cylinder head. Discard inlet valve andsprings. If the discharge valves, springs, and valve seats are defective, replace them.

    7. Remove base plate or adapter mounting capscrews. Use a soft hammer or mallet to break seal. Cleanseal material from surfaces.

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  • 10 AIR COMPRESSOR: BENDIX TU-FLO 501

    8. Before removing the connecting rods, mark each rod and its cap. Connecting rods are matched totheir own cap for proper bearing fit and parts should not be interchanged. Straighten the lock tabs onconnecting rod locks and remove bolts and bearing caps. Push the piston with connecting rod out top ofcylinders of the crankcase (Figure 10 ).

    Figure 10 Connecting Rod Out Top of Cylinders

    9. Reassemble bearing caps on their respective connecting rods.

    10. Remove piston rings from piston.

    11. Remove pistons from connecting rods by removing wrist pin lock wires or teflon plugs and press the wristpins from pistons and connecting rods. If wrist pin bushing is excessively worn, press out worn bushingand press in new bushing.

    12. Remove key from crankshaft. Through drive type compressors may have a crankshaft key at each end.Remove drive end cover. Remove end cover.

    13. Remove both small seal rings from crankcase and O-ring from the front end cover.

    14. Remove capscrews from rear end cover and remove rear end cover. Use care in removing end cover soas not to damage main bearing if bearing is used.

    15. Remove both small seal rings from crankcase and O-ring from end cover.

    16. If compressor is equipped with ball type main bearings, press crankshaft and ball bearings from crankcase.Then press bearings from crankshaft.

    17. Remove unloader spring, spring saddle and spring seat from the inlet cavity of crankcase using a longnose pliers.

    18. Remove unloader plunger and guides.

    19. Position a shop cloth over the inlet cavity and apply air pressure to governor mounting pad unloader port toblow the unloader pistons out of their bores and into the inlet cavity.

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 11

    7. CLEAN AND INSPECTClean all parts using cleaning solvent to remove all dirt, oil and grease. Use compressed air to dry parts.

    7.1. CYLINDER HEAD

    Scrape off all cylinder head gasket material from mounting surface. Remove all carbon deposits from dischargecavities and any rust and scale from cooling cavities of cylinder head. Scrape all foreign matter from the bodysurfaces and use compressed air to blow dirt from all cavities. Inspect cylinder head for cracks or damage.

    Inspect discharge valve seats for nicks, cracks and excessive wear and replace if necessary. Discharge valvestop should be inspected for wear and replaced if excessive peening has occurred. To determine if excessivepeening has occurred, measure discharge valve travel. Valve travel should not exceed .057 inch (1.448mm).To remove discharge valve stops, refer to Step No. 6 in DISASSEMBLE.

    Valve stop bores in the cylinder head must be inspected for excessive scoring. Replace with new cylinderhead body if excessive scoring is present.

    7.2. CRANKCASE

    Scrape all gasket material from crankcase mounting surface and cylinder head mounting. Clean all carbon anddirt from inlet and unloader passages. Use compressed air to blow excessive dirt and carbon deposits fromunloader passages. Clean all oil passages in crankcase.

    Inspect crankcase surfaces for cracks and damage.

    On compressors with ball bearing main bearings, the difference between the O.D. of the outer race and theI.D. of the crankcase bore should be .0000 - .0015 inch (.000 - .0381mm) loose to maintain the correctpress fit. Replace crankcase if the fit is too loose.

    On compressors with sleeve-type main bearings, the difference between the O.D. of the crankshaft journal andmain bearing I.D. must not exceed .0065 inch (.1651mm). If clearance is greater than .0065 inch (.1651mm),the end cover or main bearing must be replaced.

    Check the unloader bore bushings to be sure they are not worn, rusted or damaged. If bushings are to bereplaced, they can be removed by running a 1/8 pipe thread tap into the bushing and inserting a 1/8 pipethreaded rod and pulling the bushing straight up and out. Do not use an easy-out for removing these bushings.If inlet valve seats are worn or damaged, so they cannot be reclaimed by facing, they should be replaced.

    Cylinder bores should be checked with an inside micrometer or calipers (Figure 11 ).

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  • 12 AIR COMPRESSOR: BENDIX TU-FLO 501

    Figure 11 Measuring Cylinder Bores

    Cylinder bores which are scored or out-of- round by more than .001 inch (.0254mm) or tapered more than .002inch (.0508mm) should be rebored or honed oversize. Over-sized pistons and piston rings are available in .010inch (.2540mm), .020 inch (.5080 mm) and .030 inch (.7620mm) oversizes. Cylinder bores must be smooth,straight and round. Clearance between cast iron pistons and cylinder bores should be between .002 inch(.0508mm) minimum and .004 inch (.1016mm) maximum (Figure 12 ).

    Figure 12

    7.3. PISTONS

    Check pistons for scores, cracks or enlarged ring grooves. Measure piston with a micrometer in relation tocylinder bore diameter.

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 13

    Clearance between the cast iron pistons and cylinder bores should be between .002 inch (.0508mm) minimumand .004 inch (.1016mm) maximum (Figure 12 ).

    Check the fit of the wrist pin to the pistons and connecting rod bushings. Wrist pin should be a light press fit inthe piston. If wrist pin is a loose fit, the piston and pin assembly should be replaced. Check the fit of wrist pinin connecting rod bushing by rocking the piston. This clearance should not exceed .0007 inch (.0178mm).Replace the wrist pin bushings if excessive clearance is found.

    Wrist pin bushings should be reamed after being pressed into the connecting rods. Wrist pin clearance isbetween .5314 - .5317 inch (13.500 - 13.505mm). Install new wrist pin lock wires.

    Check the ring gap with rings positioned in cylinder bores and fit of piston in ring grooves. Refer to Figure 12for correct gap and groove clearances specifications.

    7.4. CRANKSHAFT

    Check crankshaft threads, keyways, tapered ends and all machined and ground surfaces for wear, scoresor damage. Standard crankshaft journals are 1.1250 - 1.1241 inch (28.575 - 28.552mm) diameter. If thecrankshaft journals are excessively scored or worn or out-of-round and cannot be reground, the crankshaftmust be replaced. Connecting rod bearing inserts are available in .010 - .020 inch (.254 - .508mm) and .030inch (.762mm) undersizes for compressors with reground crankshafts.

    Main bearing journals must be maintained so the ball bearings are a snug fit or so that no more than .0065 inch(.1651mm) clearance exists between the precision sleeve main bearing and the main bearing journals on thecrankshaft. In crankshafts fitted with oil seal rings, the oil seal ring groove or grooves must not be worn. Thering groove walls must have a good finish and they must be square. Check to be sure the oil passages areopen through the crankshaft.

    7.5. END COVER

    Check end covers for cracks and external damage. If main bearings are installed in the end cover, check forexcessive wear and flat spots and replace them if required. The oil seals should be replaced using a press.

    7.6. CONNECTING ROD BEARINGS

    Used (old) bearing inserts must be replaced. Connecting rod caps are not interchangeable. The locking slotsof the connecting rod and cap should be positioned adjacent to each other. Clearance between the connectingjournal and the connecting rod bearing must not be less than .0003 inch (.00762mm) or more than .0021 inch(.05334mm) after rebuilding.

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  • 14 AIR COMPRESSOR: BENDIX TU-FLO 501

    8. REPAIR8.1. DISCHARGE VALVES, VALVE STOPS AND SEATS (FIGURE 13 )

    Figure 13 Discharge Valve, Valve Stop and Seat

    If the discharge valve seats merely show signs of slight wear, they can be dressed by using a lapping stone,grinding compound and grinding tool. If the discharge valve stops are to be replaced, an application of a sealeris required, such as Loctite Retaining Compound #75. Be sure that the press fit between the discharge valvestop outside diameter and the valve stop bore in the cylinder head is a minimum of .0008 inch (.02032mm) anda maximum of .0028 inch (.07112mm). If this fit cannot be maintained, a new cylinder head body must be used.Be sure to completely support the outside top of the cylinder head casting while pressing in the replacementstops. Install the new discharge valve springs and valves. Screw in the discharge valve seats. Dischargevalve travel should be between .041 - .057 inch (1.0414 - 1.4478mm).

    8.2. DISCHARGE VALVES LEAKAGE TEST

    To test for leakage by the discharge valves, apply 100 psi air pressure through the cylinder head dischargeport and apply a soap solution to the discharge valves and seats. A slight leakage in the form of soapbubbles is permissible. If excessive leakage is found, leave the air pressure applied and with the use of afibre or hardwood dowel and a hammer, tap the discharge valves off their seats several times. This will helpthe valves to seat and should reduce the leakage. With the air pressure still applied at the discharge portof the cylinder head, check for leakage around the discharge valve stops exposed on the top of the cylinderhead casting. No leakage is permitted.

    8.3. INLET VALVES AND SEATS

    Inlet valves and springs should be replaced. If the inlet valve seats show signs of slight nicks or scratches,they can be redressed with a fine piece of emery cloth or by lapping stone, grinding compound and grindingtool. If the seats are damaged to the extent that they cannot be reclaimed, they must be replaced. Thedimensions from the top of the cylinder block to the inlet valve seat should not exceed .113 inch (2.870mm)nor be less than .101 inch (2.565mm) (Figure 14 ).

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 15

    Figure 14 Inlet Valve and Seat

    9. REASSEMBLENOTE All flange mounted compressors must be assembled without a gasket between the crankcaseand flange adapter and some compressors do not require gaskets on the end cover. Install the newcrankcase gaskets only where they were removed during disassembly. Failure of the compressor wouldresult if gaskets are used when not required.

    1. On compressors which use a ball type main bearing, press the ball bearing onto the correct end of thecrankshaft. Position the ball bearing and the crankshaft in the crankcase making sure the drive end of thecrankshaft is positioned in the crankcase as marked before disassembly. Carefully press the crankshaftand ball bearing into the crankcase using an arbor press.

    2. On compressors with a front ball bearing, place two small seal rings in the countersunk holes at the front ofthe crankcase, as well as an end cover gasket. Install the front end cover in proper position as markedbefore disassembly taking care not to damage the new oil seal.

    3. On compressors with a rear ball bearing, place two small seal rings in countersunk at the rear of thecrankcase. In one application a gasket is used and in another a large O-ring is placed in the counterboreat the rear of the crankcase. These are in addition to the seal rings. Install the rear end cover in the properposition as marked before disassembly. On some compressors the area for the two small seal rings hasbeen increased slightly and the seal ring thickness increased. When the thicker O-rings are used, aretaining ring will also be used as shown in Figure 15 .

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  • 16 AIR COMPRESSOR: BENDIX TU-FLO 501

    Figure 15 Use of Retaining Ring

    4. On compressors with a sleeve bearing either front or rear, place the two small seal rings in the countersunkholes in the crankcase. Where seal rings are used, an end cover gasket MUST NOT be used. Place theO-ring seal in the groove around the flange adapter or the end cover, and affix the thrust washer.

    5. Install the flange adapter or end cover in the proper position as marked before disassembly taking care notto damage the sleeve bearing.

    6. Secure the flange adapter, front or rear cover to the crankcase by tightening the capscrews to thefollowing torque values.

    a. 7/16 Capscrews, Cast Iron Flange Adapter, 38 - 45 ft-lbs. (51.5 - 61 Nm)b. 7/16 Capscrews, Cast Aluminum End Cover, 25 - 30 ft-lbs. (34 - 40.7 Nm)c. 5/16 Capscrews or Stud and Nut, All End Covers, 15 - 18 ft-lbs. (20.3 - 24.4 Nm)d. 7/16 Capscrews, Through Drive Compressor with Cast Iron End Covers, 25 - 30 ft-lbs. (34 - 40.7 Nm)

    7. If new wrist pins are being installed, they should be pressed into the connecting rods so that the oil holein the bushing lines up with the one in the rod.

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 17

    8. The new bushings should be reamed or honed to provide .0001 - .0006 inch (.00254 - .01524mm)clearance on the wrist pin. Position the connecting rod in the piston and press in the wrist pin. Somecompressors will have the wrist pin secured in the piston by a lock wire extending through matching holesin wrist pin and piston boss, anchored in a hole in the side wall of the piston. If the original pistons areused, the wrist pin must be pressed in so the hole in the wrist pin aligns with that of the piston. Securesame by inserting the new lockwire through the hole in piston and wrist pin and lock the wire by snappingthe short 90 degree section into the lockwire hole in the bottom of the piston.

    Later design compressors will have the wrist pin secured by Teflon buttons in either end of the wrist pin,allowing the wrist pin to float. The Teflon buttons may be used with either new or old wrist pins.

    9. The late design pistons have two rings above the wrist pin and one below. Install piston rings in the correctlocation with ring pipmarks up. Stagger the position of ring gaps. Prelubricate piston, rings, wrist pin andconnecting rod bearings with clean engine oil before installing them in the compressor.

    10. Remove connecting rod bearing cap from connecting rod. Turn crankshaft so that one of the connectingrod journals is in the downward center position. Install crankshaft journal rod bearing in connectingrod and rod cap.

    11. Stagger piston rings so that the ring gaps are 120 degrees apart. Apply engine oil to rings, piston and wristpin. Use ring compressor and compress piston rings.

    12. Install piston/rod assembly into correct cylinder (the one it was removed from). Tap ring compressorflush with block.

    13. Use hammer handle and tap piston into cylinder bore, guiding rod/bearing onto crankshaft journal.

    14. Attach bearing cap to connecting rod making sure that a lock strap is positioned on the cap. Tighten therod bolts to 120 - 150 inch pounds or 10 - 12 ft-lbs. (13.5 - 16.3 Nm). Bend lock strap prongs againsthex head of bolts.

    15. Install remaining piston and connecting rod in the same manner.

    16. A new unloader kit (Figure 16 ) should be used when reassembling the compressor. The pistons in thekit are prelubricated with a special lubricant and require no further lubrication. Install unloader pistonsin their bores taking care not to cut O-ring. Position unloader plungers in their guides and slip them inand over the tops of the pistons. Install unloader spring seat in crankcase inlet cavity. A small hole isdrilled in crankcase for this purpose. Position the saddle between unloader piston guides so its forks arecentered on guides. Install unloader spring making sure it seats over the spring seats both in crankcaseand on saddle. Install inlet valve guides, then position valves in their guides. There should be a loosesliding fit between the guides and valves.

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  • 18 AIR COMPRESSOR: BENDIX TU-FLO 501

    Figure 16 Unloader Mechanism

    17. Install the inlet valve springs in the cylinder head by applying a turning motion to the spring after it is inthe head. The turning motion should dig the spring wire into the spring seat in the bottom of the springbore in the head. Should this procedure fail after repeated attempts, use a very small quantity of greaseto hold them in place, just enough to keep the springs from falling out. Place the cylinder head gasketon the cylinder block. Carefully align the cylinder head assembly on the block and install the capscrews,tightening them evenly to a torque of 25 - 30 ft-lbs. (34 - 40.7 Nm).

    18. Position the base plate or base adapter gasket on the crankcase and install the base plate adapteras marked before disassembly. Tighten the six capscrews securing the cast iron base adapter evenlyto a torque of 38 - 45 ft-lbs. (51.5 - 61 Nm) and 12 - 16 ft lbs. (16.26 - 21.69 Nm) for base plate oraluminum cover.

    10. TESTINGTo properly test a compressor under operating conditions, a test rack for correct mounting, cooling, lubricatingand driving the compressor is necessary. Such tests are not compulsory if the unit has been carefully rebuilt byan experienced person. A compressor efficiency or build-up test can be run which is not too difficult. An enginelubricated compressor must be connected to an oil supply line of at least 15 psi during the test and an oil returnline must be installed to keep the crankcase drained.

    Connect to the compressor discharge port a reservoir with a volume of 1500 cu. in. including the volume ofconnecting line. With the compressor operating at 2100 RPM, the time required to raise the reservoirspressure from 85-100 psi should not exceed 7 seconds. During this test, the compressor should be checkedfor gasket leakage and noisy operation as well as unloader operation and leakage.

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    11. TROUBLESHOOTINGThe following is a listing of the most commonly experienced compressor deficiencies and their probable causes.

    Table 1 Troubleshooting Chart

    Condition Possible Cause Remedy

    Compressor passesexcessive oil as evidencedby presence of oil atexhaust ports of valving orseeping from air strainer.

    Restricted air intake. Check engine or compressor air cleaner andreplace if necessary. Check compressor airinlet line for kinks. Recommended maximumair inlet restriction is 25 of water.

    Restricted oil return (toengine).

    Check for excessive bends, kinks, andrestrictions in the oil return line.

    Poorly filtered inlet air. Check for damaged, defective or dirty air filteron engine or compressor.

    Insufficient compressorcooling (compressor runshot).

    For air-cooled compressor or air-cooledportions of the compressor:

    A. Remove accumulated grease, grime, or dirtfrom the cooling fins. Replace componentsfound damaged.

    B. Air-cooled compressors should not be usedon engines equipped with fan clutches.

    For water-cooled compressor or water-cooledportions of the compressor

    A. Check for proper coolant line sizes.Minimum recommended size is 1/2 O.D.tubing.

    B. Check the coolant flow through thecompressor.

    C. Water temperature should not exceed200F.

    Contaminants not beingregularly drained fromsystem reservoirs.

    Check reservoir drain valves to insure that theyare functioning properly. It is recommendedthat the vehicle should be equipped withfunctioning automatic drain valves, or have allreservoirs drained to zero psi daily.

    Compressor runs loaded anexcessive amount of time.

    Check for systems leaks and repair.

    Excessive enginecrankcase pressure.

    Test for excessive engine crank-case pressureand replace or repair crankcase ventilationcomponents as necessary. (An indication ofcrankcase pressure is a loose or partially lifteddipstick.)

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  • 20 AIR COMPRESSOR: BENDIX TU-FLO 501

    Table 1 Troubleshooting Chart (cont.)

    Condition Possible Cause Remedy

    Excessive engine oilpressure.

    Check the engine oil pressure with a testgauge and compare the reading to the enginespecifications. Minimum oil supply line size is1/4 O.D. tubing.

    Faulty compressor. Replace or repair the compressor onlyafter making certain none of the precedinginstallation defects exist.

    Noisy compressoroperations

    Loose drive gear or pulley. If the compressor crankshaft surface or itskeyway is damaged, it is an indication ofloose drive components. If damage to thecompressor crankshaft is detected, replace thecompressor or the crankshaft. When installingthe drive gear or pulley, torque the crankshaftnut to 100 foot pounds. DO NOT BACK OFFTHE CRANKSHAFT NUT TO ALIGN THECOTTER PIN AND CASTELLATED NUT.(Some compressors do not use castellatednuts.) DO NOT USE IMPACT WRENCHES.

    Excessively worn drivecoupling or gears.

    Replace as necessary. (Non-metallic gearsshould be replaced when the compressor ischanged.) 501 drive gear should be metal typeon Detroit Diesel engine.

    Compressor cylinderhead or discharge linerestrictions.

    Inspect the compressor discharge port anddischarge line for carbon build-up. If carbonis detected, check for proper cooling to thecompressor. Inspect the discharge line forkinks and restrictions. Replace discharge lineas necessary.

    Worn or burned outbearings.

    Check for clean engine oil and proper oilpressure in the compressor. Minimum requiredoil pressure: 5 psi engine idling, 15 psimaximum governed engine rpm. Check forexcessive oil temperature should not exceed240F.

    Faulty compressor. Replace or repair the compressor afterdetermining none of the preceding installationdefects exist.

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 21

    Table 1 Troubleshooting Chart (cont.)

    Condition Possible Cause Remedy

    Excessive build-up andrecovery time. Compressorshould be capable ofbuilding air systemfrom 85 - 100 psi in 40seconds with engine at fullgoverned rpm. Minimumcompressor performanceis certified to meet Federalrequirements by the vehiclemanufacturer. Do notdownsize the originalequipment compressor.

    Dirty air induction filter. Inspect engine or compressor air filter andreplace if necessary.

    Restricted induction line. Inspect the compressor air induction linefor kinks and restrictions and replace asnecessary.

    Restricted discharge lineor compressor dischargecavity.

    Inspect the compressor discharge port andline for restrictions and carbon build-up. If acarbon build-up is found, check for propercompressor cooling. Replace faulty sectionsof the discharge line.

    Slipping drive components. Check for faulty drive gears and couplings andreplace as necessary. Check the condition ofdrive belts and replace or tighten, whicheveris appropriate.

    Excessive air systemleakage.

    Build system pressure to governor cutoutand allow the pressure to stabilize for oneminute. Using the dash gauge, note the systempressure and the pressure drop after twominutes.The pressure drop should not exceed:

    A. 2 psi in each reservoir for a single vehicle.

    B. 6 psi in each reservoir for a tractor andtrailer.

    C. 8 psi in each reservoir for a tractor and 2trailers.

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  • 22 AIR COMPRESSOR: BENDIX TU-FLO 501

    Table 1 Troubleshooting Chart (cont.)

    Condition Possible Cause Remedy

    Sticking unloader pistonsand plungers.

    Check the operation of the unloading pistons inthe inlet cavity of the compressor. Both pistonsshould have the plunger flanges resting on theinlet cavity floor when the compressor is loaded(pumping air). If the pistons and plunger arenot fully retracted, check for proper operationof the compressor air governor. If the governoris operating properly, replace the unloaderpistons and plungers and inspect their boresin the cylinder block. Clean and lubricate asnecessary. Inspect for bent, kinked or blockedtubing leading to or from the governor.

    Faulty compressor. Replace or repair the compressor afterdetermining none of the preceding installationdefects exist.

    Compressor fails to unload Faulty governor or governorinstallation.

    Test the governor for proper operation andinspect air lines to and from the governor forkinks or restrictions. Replace or repair thegovernor or its connecting air lines.

    Faulty or worn unloaderpistons or bores.

    Inspect for worn, dirty or corroded unloaderpistons and their cylinder block bores. Replaceas necessary.

    Compressor leaks oil Damaged mounting gasket. Check the compressor mounting bolt torque.If the mounting bolt torque is low, replace thecompressor mounting gasket before retorquingthe mounting bolts.

    Cracked crankcase,cylinder block or endcover.

    Visually inspect the compressor exterior forcracked or broken components. Cracked orbroken crankcases or mounting flanges canbe caused by loose mounting bolts. The endcover can be cracked by over-torquing fitting orplugs installed in the end cover. Replace orrepair the compressor as necessary.

    Loose end cover or cylinderblock capscrews.

    Check the capscrew torques and tighten asnecessary.

    Loose oil supply or returnline fittings.

    Check the torque of external oil line fittings andtighten as necessary.

    Porous compressor casting. Replace the compressor if porosity is found.

    Mounting flange or endcover, O-ring or gasketmissing, cut, or damaged.

    Replace as necessary.

    Compressor constantlycycles (compressorremains unloaded for avery short time.)

    Leaking compressor. Remove the compressor inlet air strainer orfitting. With the compressor unloaded (notcompressing air), check for air leakage aroundthe unloader pistons. Replace as necessary.

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 23

    Table 1 Troubleshooting Chart (cont.)

    Condition Possible Cause Remedy

    Faulty governor. Test the governor for proper operation andrepair or replace as necessary.

    Excessive system leakage Test for excessive system leakage asinstructed under Excessive build-up andrecovery time, Remedy 5. Reduce leakagewherever possible.

    Excessive reservoircontaminants.

    Drain reservoirs.

    Compressor leaks coolant Improperly installed plugsand coolant line fittings

    Check torque of fittings and plugs and tightenas necessary. Over-torque fittings and plugscan crack the head or block casting.

    Freeze cracks due toimproper anti-freezestrength.

    Test anti-freeze and strengthen as necessary.Check coolant flow through compressor toassure the proper anti-freeze mixture reachesthe compressor.

    Faulty compressor (porouscastings).

    If casting porosity is detected, replace thecompressor.

    Compressor head gasketfailure

    Restricted discharge line. Clear restriction or replace line.

    Loose head bolts. Tighten evenly to a torque of 25 - 30 t-lbs. (34- 40.7 Nm).

    Faulty compressor or headgasket.

    Check for rough or poorly machined heador block surfaces. Replace necessarycomponents.

    12. SPECIFICATIONS12.1. COMPRESSOR DATA

    Table 2 Compressor Data Chart

    Number of cylinders 2

    Bore Size 2.625 in.

    Stroke 1.50 in.

    Piston displacement at 1250 RPM 12 cu. ft.

    Piston displacement per revolution 16.5 cu. in.

    Maximum recommended RPM (naturally aspirated) 3000

    Minimum coolant flow at maximum RPM 2.5 gal./min.

    Horsepower required at 3000 RPM against 100 PSI headpressure

    4.9 H.P.

    Recommended minimum discharge line size 5/8 in. OD Copper Tube

    Recommended minimum oil return line size 5/8 in. OD Tubing

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  • 24 AIR COMPRESSOR: BENDIX TU-FLO 501

    Table 2 Compressor Data Chart (cont.)

    Recommended minimum oil supply line size 1/4 in. OD Tubing

    Recommended minimum unloader line size 1/4 in. OD Tubing

    Recommended minimum inlet cavity line size (whencompressor is connected to engine air cleaner)

    5/8 in. ID Tubing

    Recommended minimum coolant line size 1/2 in. OD Tubing

    Recommended maximum inlet air temperature 250F

    Recommended maximum discharge air temperature 400F

    Minimum pressure required to unload 60 PSI

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  • AIR COMPRESSOR: BENDIX TU-FLO 501 25

    12.2. MEASUREMENTS

    Table 3 Measurements Chart

    Application Inches Millimeters

    Maximum Discharge Valve Travel .057 1.447

    Crankcase with Ball Bearing Crankshaft Mains

    O.D. of Bearing Race and I.D. of Case Clearance 0 - .0015 0 - .0381

    Sleeve-Type Main Bearings-Difference Between O.D. ofCrankshaft and I.D. of Main Bearing Maximum

    .0065 .1651

    Cylinder Bore Out-of-Round Maximum .001 .0254

    Cylinder Bore Taper Maximum .002 .0508

    Oversized Pistons Available .010 .2540

    .020 .5080

    .030 .7620

    Cylinder Bore to Piston Clearance .002 - .004 .0508 - .1016

    Piston to Piston Pin Bushing Clearance Maximum .0007 .0177

    New Reamed Piston Pin Bushing to Pin Clearance .5314 - .5317 13.498 - 13.505

    Standard Crankshaft Journals 1.1250 - 1.1241 28.575 - 28.552

    Oversized Rod Bearings Available .010 - .020 .254 - .508

    .030 .762

    Clearance Between Rod Journal and Rod Bearing

    Not Less Than .0003 .00762

    Not More Than .0021 .05334

    Discharge Valve Stop Outside Diameter and Valve StopBore in Cylinder Head is

    Minimum .0008 .02032

    Maximum .0028 .07112

    Discharge Valve Travel .041 - .057 1.0414 - 1.4478

    Inlet Valve Seats Top of Cylinder Block to Inlet Valve Seat

    Maximum .113 2.870

    Minimum .101 2.565

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  • 26 AIR COMPRESSOR: BENDIX TU-FLO 501

    12.3. TORQUE CHART

    Table 4 Torque Chart

    Item* Location Ft-Lbs. Nm

    1 Crankcase and Shaft End Covers

    1 7/16 Capscrews, Cast Iron Flange Adapter 38 - 45 51.5 - 611 7/16 Capscrews, Cast Aluminum End Covers 25 - 30 34 - 40.71 7/16 Capscrews Through Drive Compressor with

    Cast Iron End Covers25 - 30 34 - 40.7

    1 5/16 Capscrew or Stud/Nut All End Covers 15 - 18 20.3 - 24.42 Connecting Rod Cap Bolts 10 - 12 13.5 - 16.3

    3 Cylinder Head Bolts 25 - 30 34 - 40.7

    4 Base Adapter 38 - 45 51.5 - 61

    4 Base Plate or Aluminum Cover 12 - 16 16.3 - 21.7

    * Refer to Figure 17 for torque location area.

    Figure 17 Reference for Torque Chart

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