Bendix Commercial Vehicle Systems BA-921 User Manual

®

BENDIX® BA-921® SMC SINGLE CYLINDER COMPRESSOR FOR NAVISTAR MAXXFORCE™ 11 AND 13 BIG BORE ENGINES

SD-01-1327

DESCRIPTION

The function of the air compressor is to provide, and maintain, air under pressure to operate devices in air brake systems. The Bendix® BA-921® SMC side mount compressor is a single-cylinder reciprocating compressor with a rated displacement of 15.8 cubic feet per minute at 1250 RPM.

The compressor consists of a water-cooled cylinder head assembly and an integral air cooled crankcase assembly .

The cylinder head assembly is made up of the cylinder head, cooling plate, and valve plate assembly and uses two sealing gaskets. Both the cylinder head and cooling plate are aluminum. The cylinder head contains air and water ports, as well as an unloader assembly. A cooling plate is located between the cylinder head and valve plate assemblies and assists in cooling.

The valve plate assembly consists of brazed steel plates which have valve openings and passages for air and engine coolant to ﬂ ow into, and out of, the cylinder head. The compressor's discharge valves are part of the valve plate assembly . The inlet reed valve/gasket is installed between the valve plate assembly and the top of the crankcase.

The crankcase has an open side with a machined face and locating pins. This open face is bolted directly to the side of the engine block, see Figure 3. The compressor gear engages the engine drive gear. In addition, the crankcase houses the piston assembly, connecting rod, crankshaft and related bearings.

The Bendix a safety valve to protect the compressor head in the event of, for example, a discharge line blockage downstream of the compressor. Excessive air pressure will cause the safety valve to unseat, release air pressure and give an audible alert to the operator. The safety valve is installed in the cylinder head safety valve port, directly connected to the cylinder head discharge port.

BA-921® SMC compressor is equipped with

Cylinder

Head

Valve Plate

Assembly

Crankcase

FIGURE 1 - BENDIX® BA-921® SMC COMPRESSOR

Bendix Part Number . . . . . . A

Customer Piece Number . . . . B

Compressor Serial Number . . C

FIGURE 2 - NAMEPLATE

Safety

Valve

Cooling

Plate

A nameplate is attached to a ﬂ at cast face on the side of the crankcase. It is stamped with information identifying the compressor designation, customer piece number, compressor assembly part number and serial number. Refer to Figure 2.

Unloader

Piston

Safety

Valve

Discharge

Port

Coolant

Air Inlet Port

Piston

Compressor to

engine block

mounting face

Discharge

Reed

Valves (2)

Connecting Rod

Crankshaft

FIGURE 3 - BENDIX® BA-921® SMC COMPRESSOR CUT AWAY VIEW

OPERATION

The compressor is driven by the vehicle's engine, and functions continuously while the engine is in operation. Actual compression of air is controlled by the compressor unloading mechanism operating in conjunction with a governor.

AIR INTAKE (LOADED)

Just as the piston begins the down stroke, (a position known as top dead center, or TDC), the vacuum created in the cylinder bore above the piston causes the inlet reed valve to ﬂ ex open. Atmospheric air ﬂ ows through the open inlet valve and ﬁ lls the cylinder bore above the piston. See

Figure 4.

AIR COMPRESSION (LOADED)

When the piston reaches the bottom of the stroke, (a position known as bottom dead center, or BDC), the inlet reed valve closes. Air above the piston is trapped by the closed inlet reed valve and is compressed as the piston moves upwards. When air in the cylinder bore reaches a pressure greater than that of the system pressure, the discharge reed valves open and allow air to ﬂ ow into the discharge line and air brake system.

Discharge

Cooling

Plate

Valve Plate

FIGURE 4 - OPERATION - LOADED (INTAKE)

Air

Port

Oil drain

locations

Mounting Face

Air Inlet

Port

Piston Moving Down

Discharge

Valve

Closed

Unloader

Port

Unloader

Piston

Down &

Seated

Inlet Valve Open

At the same time air ﬂ ows into the hollow center of the unloader piston through an opening in the end of the piston.

Compressed air acts on the interior surfaces of the unloader piston and, along with the unloader piston spring, holds the unloader piston in the down position, against its seat on the valve plate. See Figure 5.

NON-COMPRESSION OF AIR (UNLOADED)

When air pressure in the supply reservoir reaches the cutout setting of the governor, the governor delivers system air to the compressor unloader port. Air entering the unloader port acts on the unloader piston causing the piston to move away from its seat on the valve plate assembly . When the unloader piston is unseated, an air passageway is opened between the cylinder bore and a secondary compartment or “closed room” in the interior of the cylinder head.

As the piston moves from bottom dead center (BDC) to top dead center (TDC) air in the cylinder bore ﬂ ows past the unseated unloader piston, into the “closed room”. The size of the closed room is sufﬁ cient to accept the compressed air provided by the compressor piston without creating excessive air pressure in the “closed room”. On the piston down stroke (TDC to BDC) air ﬂ ows in the reverse direction, from the “closed room” past the unseated unloader piston and inlet reed valve, and into the cylinder bore as shown in Figure 6. Note: For optimum performance, it is recommended that the air dryer is equipped with a “turbo cut-off” feature.

Air Inlet

Air

Discharge

Port

Cooling

Plate

Valve

Plate

Inlet

Valve

Closed

FIGURE 5 - OPERATION - LOADED (COMPRESSION)

Port

Piston Moving Up

Discharge

Valve Open

Unloader

Port

Unloader

Piston

Down &

Seated

LUBRICATION

The vehicle’s engine provides a continuous supply of oil to the compressor. Oil is routed from the engine to the compressor’s oil inlet. Note: There is no external oil supply line; the oil delivery is located at the engine to compressor mounting face. This pressurized oil ﬂ ows to the precision front sleeve main bearing, via an oil passage in the crankshaft, routes pressurized oil to the connecting rod bearings and the rear journal associated with the end cover. Spray lubrication of the cylinder bore and connecting rod wrist pin bushing is obtained as oil is forced out around the crankshaft journals by engine oil pressure. Oil then falls to the bottom of the compressor crankcase and is returned to the engine through the opening at the compressor mounting ﬂ ange.

Air From Governor Unloader

Port

Closed

Room

Unloader

Piston Up &

Unseated

Air in Pistons Shuttles Back and Forth from the

Piston to the Closed Room

FIGURE 6 - OPERATION - UNLOADED

Inlet Port

Head

Bolt (6)

Coolant

In or Out

Discharge

Safety Valve

Discharge

Port

Coolant

In or Out

Governor

Connection

Unloader

Cover

CYLINDER HEAD PORT IDENTIFICATION

The cylinder head connection ports are identiﬁ ed with cast-in numerals as follows:

AIR IN 0 Compressed AIR OUT 2 Coolant IN or OUT 9 Governor Control 4

FIGURE 7 - BENDIX® BA-921® SMC COMPRESSOR CYLINDER HEAD

COOLING

The Bendix® BA-921® SMC compressor is cooled by air ﬂ owing through the engine compartment as it passes the compressor's cast-in cooling ﬁ ns and by the ﬂ ow of engine coolant through the cylinder head. Coolant supplied by the engine cooling system passes through connecting lines into the cylinder head and passes through internal passages in the cylinder head, cooling plate and valve plate assembly and returns to the engine. Figure 7 illustrates the approved coolant ﬂ ow connections. Proper cooling is important in minimizing discharge air temperatures - see the tabulated technical data on page 13 of this manual for speciﬁ c requirements.

AIR INDUCTION

The Bendix® BA-921® SMC compressors is only permitted to be naturally aspirated – use of engine turbocharger as an air source is not allowed. See Figure 8 for an example

of a naturally aspirated air induction system.

PREVENTATIVE MAINTENANCE

Regularly scheduled maintenance is the single most important factor in maintaining the air brake charging system. Refer to Table A in the Troubleshooting section starting on page A-1, for a guide to various considerations that must be given to maintenance of the compressor and other related charging system components.

Important Note: Review the Bendix performing any intrusive maintenance procedures. An extended warranty may be voided if intrusive maintenance is performed during this period.

Governor

Unloader Port

Air Dryer

EVERY 6 MONTHS, 1800 OPERATING HOURS OR AFTER EACH 50,000 MILES, WHICHEVER OCCURS FIRST, PERFORM THE FOLLOWING

Governor Reservoir

Port

Compressor

INSPECTIONS AND TESTS.

Warranty Policy before

FIGURE 8 - COMPRESSOR CHARGING SYSTEM

AIR INDUCTION

The Bendix® BA-921® SMC compressor is designed for connection to the vacuum side of the engine’s air induction system.

A supply of clean air is one of the single most important factors in compressor preventive maintenance. Since

the air supply for Bendix

BA-921® SMC compressor and engine is the engine air cleaner, periodic maintenance of the engine air ﬁ lter is necessary.

Inspect the compressor air induction system each time engine air cleaner maintenance is performed.

1. Inspect the intake hose adapters for physical damage.

Make certain to check the adapters at both ends of the intake hose or tubing.

2. Inspect the intake hose clamps and tighten them if

needed.

3. Inspect the intake hose or line for signs of drying,

cracking, chaﬁ ng and ruptures and replace if necessary.

4. Verify that the compressor inlet ﬁ tting is tight (check

torque).

5. Any metal tubes should also be tight (torqued properly)

to the mating ﬁ tting. Inspect the metal tubes for any cracks or breaks and replace if necessary.

COMPRESSOR COOLING

Inspect the compressor discharge port, inlet cavity and discharge line for evidence of restrictions and carbon build-up. If more than 1/16" of carbon is found, thoroughly clean or replace the affected parts. In some case, carbon build-up indicates inadequate cooling. Closely inspect the compressor cooling system. Check all compressor coolant lines for kinks and restrictions to ﬂ ow. Minimum coolant line size is 3/8" I.D. Check coolant lines for internal clogging from rust scale. If coolant lines appear suspicious, check the coolant ﬂ ow and compare to the tabulated technical data present in the back of this manual. Carefully inspect the air induction system for restrictions.

LUBRICATION

The compressor utilizes an internal oil feed design. Check the exterior of the compressor (i.e. around the mounting face) for the presence of oil seepage and refer to the Troubleshooting section for appropriate tests and corrective action. Refer to the tabulated technical data in the back of this manual for oil pressure minimum values.

If compressor oil passing is suspected, refer to the Troubleshooting section (starting on page A-1) for the symptoms and corrective actions to be taken. In addition, Bendix has developed the “Bendix Air System Inspection Cup”, or Bendix

BASIC™ kit, to help substantiate

suspected excessive oil passing. The steps to be followed

™

when using the BASIC

kit are presented in APPENDIX

B, on page A-16.

COMPRESSOR DRIVE

Check for noisy compressor operation, which could indicate excessive drive component wear. Adjust and/or replace as necessary. Check all compressor mounting bolts and retighten evenly if necessary . Check for leakage. Repair or replace parts as necessary.

COMPRESSOR UNLOADER & GOVERNOR

Test and inspect the compressor and governor unloader system for proper operation and pressure setting.

1. Check for leakage at the unloader port. Replace leaking or worn o-rings.

2. Make certain the unloader system lines are connected as illustrated in Figure 8.

3. Cycle the compressor through the loaded and unloaded cycle several times. Make certain that the governor cuts-in (compressor resumes compressing air) at a minimum of 105 psi (cut-out should be approximately 15 - 20 psi greater than cut-in pressure). Adjust or replace the governor as required.

4. Note that the compressor cycles to the loaded and unloaded conditions promptly. If prompt action is not noted, repair or replace the governor and/or repair the compressor unloader.

IMPORTANT NOTE

Replacement air governors must have a minimum cut-in pressure of 100 psi. The cut-in pressure is the lowest system pressure registered in the gauges before the compressor resumes compressing air.

Compressors with no signal line to the unloader port should have a vent cap (e.g. Bendix P/N 222797) installed in the port. Under no circumstances should the port be plugged or left open.

OIL PASSING

All reciprocating compressors pass a minimal amount of oil. Air dyers will remove the majority of oil before it can enter the air brake system. For particularly oil sensitive systems, the Bendix® PuraGuard® system can be used in conjunction with a Bendix® air dryer.

SERVICE TESTS

LEAKAGE TESTS

GENERAL

The compressor operating and leakage tests listed below need not be performed on a regular basis. These tests should be performed when it is suspected that leakage is substantially affecting compressor build-up performance, or when it is suspected that the compressor is “cycling” between the loaded (pumping) and unloaded (nonpumping) modes due to unloader leakage.

IN SERVICE OPERATING TESTS

Compressor Performance: Build-up Test

This test is performed with the vehicle parked and the engine operating at maximum recommended governed speed. Fully charge the air system to governor cut-out (air dryer purges). Pump the service brake pedal to lower the system air pressure below 80 psi using the dash gauges. As the air pressure builds back up, measure the time from when the dash gauge passes 85 psi to the time it passes 100 psi. The time should not exceed 40 seconds. If the vehicle exceeds 40 seconds, test for (and ﬁ x) any air leaks, and then re-test the compressor performance. If the vehicle does not pass the test the second time, use the Advanced Troubleshooting Guide for Air Brake Compressors, starting on page A-1 of this document to assist your investigation of the cause(s).

See the standard Air Brake System and Accessory Leakage test on Page A-14 (Test 2).

Note: Leakage in the air supply system (components before the supply reservoir such as the governor, air dryer , reservoir drain cocks, safety valve, and check valves) will not be registered on the vehicle dash gauges and must be tested separately. Refer to the various maintenance manuals for individual component leakage tests and the Bendix “Test and Checklist” published in the Bendix Brake System Handbook (BW5057) and on the back of the Bendix Dual Circuit Brake System Troubleshooting Card (BW1396).

Air

CYLINDER HEAD

Check for cylinder head gasket air leakage.

1. With the engine running, lower air system pressure to 60 psi and apply a soap solution around the cylinder head. Check the gasket between the cylinder head and valve plate assembly, as well as the inlet reed valve/gasket between the valve plate assembly and crankcase for air leakage.

2. No leakage is permitted. If leakage is detected, replace the compressor or repair the cylinder head using a genuine Bendix® maintenance kit available from an authorized Bendix® parts outlet.

Note: All new vehicles are certiﬁ ed using the FMVSS 121 test (paragraph S5.1.1) by the vehicle manufacturer, however the above test is a useful guide for in-service vehicles.

Optional Comparative Performance Check

It may be useful to also conduct the above test with the engine running at high idle (instead of maximum governed speed), and record the time required to raise the system pressure a selected range (for example, from 90 to 120 psi, or from 100 to 120 psi, etc.) in the vehicle’s maintenance ﬁ les. Subsequent build-up times throughout the vehicle’s service life can then be compared to the ﬁ rst one recorded. (Note: the 40 second guide in the test above does not apply to this build-up time.) If the performance degrades significantly over time, you may use the Advanced Troubleshooting Guide for Air Brake Compressors, starting on page A-1 of this document, to assist investigation of the cause(s).

Note: When comparing build-up times, be sure to make an allowance for any air system modiﬁ cations which would cause longer times, such as adding air components or reservoirs. Always check for air system leakage.

INLET, DISCHARGE & UNLOADER

In order to test the inlet and discharge valves and the unloader piston, it is necessary to have shop air pressure and an assortment of ﬁ ttings. A soap solution is also required.

1. With the engine shut off, drain ALL air pressure from the vehicle.

2. Disconnect the inlet and discharge lines and remove the governor or its line or adapter ﬁ tting.

3. Apply 120-130 psi shop air pressure to the unloader port and soap the inlet port. Leakage at the inlet port should not exceed 50 sccm.

4. Apply 120-130 psi shop air pressure to the discharge port and then apply and release air pressure to the inlet port. Soap the inlet port and note that leakage at the inlet port does not exceed 20 sccm.

If excessive leakage is noted in Tests 3 or 4, replace or repair the compressor using genuine Bendix® replacements or maintenance kits available from any authorized Bendix parts outlet.

While it is possible to test for inlet, discharge, and unloader piston leakage, it may not be practical to do so. Inlet and discharge valve leakage can generally be detected by longer compressor build-up and recovery times. Compare current compressor build-up times with the last several recorded times. Make certain to test for air system leakage, as described under In Service Operating Tests, before making a determination that performance has been lost.

Unloader leakage is generally exhibited by excessive compressor cycling between the loaded and unloaded condition.

1. With service and supply system leakage below the maximum allowable limits and the vehicle parked, bring system pressure to governor cut-out and allow the engine to idle.

2. The compressor should remain unloaded for a minimum of 5-10 minutes. If compressor cycling occurs more frequently and service and supply system leakage is within tolerance, replace the compressor or repair the compressor unloader system using a genuine Bendix maintenance kit available from authorized Bendix parts outlets.

COMPRESSOR REMOVAL & DISASSEMBLY

GENERAL

The following disassembly and assembly procedure is presented for reference purposes and pre-supposes that a rebuild or repair of the compressor is being undertaken. Several maintenance kits are available and the instructions provided with these parts and kits should be followed in lieu of the instructions presented here.

MAINTENANCE KITS & SERVICE PARTS FOR

BENDIX

COMPRESSOR ONLY

Cylinder Head Gasket Kit ...................................K023764

Unloader Kit ........................................................K046477

Discharge Safety Valve ......................................800534

Compressor Seal Kit...........................................K051352

Compressor to Engine Mounting Face Sealant (Supplied by the Engine Manufacturer)

All components shown in Figure 9 with a key number are available in kits and/or as individual service parts.

BA-921® SMC SINGLE CYLINDER

GENERAL SAFETY GUIDELINGS IMPORTANT! PLEASE READ AND FOLLOW

THESE INSTRUCTIONS TO AVOID PERSONAL INJURY OR DEATH:

When working on or around a vehicle, the following general precautions should be observed at all times:

1. Park the vehicle on a level surface, apply the parking brakes, and always block the wheels. Always wear safety glasses. Where speciﬁ cally directed, the parking brakes may have to be released, and/or spring brakes caged, and this will require that the vehicle be prevented from moving by other means for the duration of these tests/procedures.

2. Stop the engine and remove ignition key when working under or around the vehicle. When working in the engine compartment, the engine should be shut off and the ignition key should be removed. Where circumstances require that the engine be in operation, EXTREME CAUTION should be used to prevent personal injury resulting from contact with moving, rotating, leaking, heated or electrically charged components.

3. Do not attempt to install, remove, disassemble or assemble a component until you have read and thoroughly understand the recommended procedures. Use only the proper tools and observe all precautions pertaining to use of those tools.

4. If the work is being performed on the vehicle’s air brake system, or any auxiliary pressurized air systems, make certain to drain the air pressure from all reservoirs before beginning ANY work on the vehicle. If the vehicle is equipped with a Bendix® AD-IS® air dryer system or a dryer reservoir module, be sure to drain the purge reservoir.

5. Following the vehicle manufacturer’s recommended procedures, deactivate the electrical system in a manner that safely removes all electrical power from the vehicle.

6. Never exceed manufacturer’s recommended pressures.

7. Never connect or disconnect a hose or line containing pressure; it may whip. Never remove a component or plug unless you are certain all system pressure has been depleted.

8. Use only genuine Bendix® brand replacement parts, components and kits. Replacement hardware, tubing, hose, ﬁ ttings, etc. must be of equivalent size, type and strength as original equipment and be designed speciﬁ cally for such applications and systems.

9. Components with stripped threads or damaged parts should be replaced rather than repaired. Do not attempt repairs requiring machining or welding unless speciﬁ cally stated and approved by the vehicle and component manufacturer.

10. Prior to returning the vehicle to service, make certain all components and systems are restored to their proper operating condition.

11. For vehicles with Automatic T raction Control (A TC), the ATC function must be disabled (ATC indicator lamp should be ON) prior to performing any vehicle maintenance where one or more wheels on a drive

axle are lifted off the ground and moving.

REMOVAL

In many instances it may not be necessary to remove the compressor from the vehicle when installing the various maintenance kits and service parts. The maintenance technician must assess the installation and determine the correct course of action. These instructions are general and are intended to be a guide. In some cases additional preparations and precautions are necessary. In all cases follow the instructions contained in the vehicle maintenance manual in lieu of the instructions, precautions and procedures presented in this manual.

1. Block the wheels of the vehicle and drain the air pressure from all the reservoirs in the system.

2. Drain the engine cooling system and the cylinder head of the compressor. Identify and disconnect all air , water and oil lines leading to the compressor.

3. Remove as much road dirt and grease from the exterior of the compressor as possible.

4. Remove the discharge ﬁ tting, if applicable, and note their position on the compressor to aid in reassembly.

5. Remove any supporting bracketing attached to the compressor and note their positions on the compressor to aid in reassembly.

6. Remove the six mounting bolts that retain the compressor to the side of the engine block. Note the position of the six mounting bolts. Two of the six bolts are shorter and must be installed in their original locations. Remove the compressor from the vehicle.

7. Inspect drive gear and associated drive parts for visible wear or damage. If the compressor drive gear is worn or damaged, the compressor must be replaced. Refer to the Engine Manufacturers service manual to address the associated engine drive parts.

8. If the compressor is being replaced stop here and proceed to “Installing the Compressor” at the end of the assembly procedure. (Note: Replacement compressors come with the drive gear pre-assembled on the compressor.)

PREPARATION FOR DISASSEMBLY

Refer to Figure 9 during the entire disassembly and assembly procedure.

Place a clean rag over the openings that expose the gear and crankshaft / connecting rod assembly. No contamination is permitted in these areas.

Remove the balance of the road dirt and grease from the exterior of the compressor with a cleaning solvent. If the rear end cover is being removed from the compressor under repair, mark it, along with the two cap screws, in relation to the crankcase. It is also recommended to mark the relationship of the cylinder head, cooling plate, valve plate assembly, and crankcase.

A convenient method to indicate the above relationships is to use a metal scribe to mark the parts with numbers or lines. Do not use marking methods, such as chalk, that can be wiped off or obliterated during rebuilding.

Prior to disassembly, make certain that the appropriate kits are available.

CYLINDER HEAD

1. Remove the discharge safety valve (9) from the cylinder head.

2. To restrain the spring force exerted by the return spring (3) of the unloader assembly, hold the unloader cover in place while removing the two unloader cover cap screws. Carefully release the hold on the unloader cover until the spring force is relaxed, then remove the unloader cover.

3. Remove the unloader cover gasket (4).

4. Remove the balance piston (5) with its o-ring (6); return spring (3) and the unloader piston assembly (7) which includes the unloader piston, two outer o-rings and two guide bushings from the cylinder head.

5. Remove the six hex head bolts from the cylinder head. Note: The ﬁ ve hex bolts located towards the perimeter of the cylinder head retain the cylinder head directly to the crankcase. The single hex bolt in the center of the cylinder head holds the cylinder head, cooling plate and valve plate assembly together; independent of the crankcase.

6. Gently tap the cylinder head, cooling plate and valve plate assembly with a soft mallet to break the gasket seal between the valve plate assembly and the crankcase. Lift the cylinder head with cooling plate and valve plate assembly off the crankcase.

7. Remove the metal inlet reed valve/gasket (1).

Note: Always

Replace Safety

Valve in Original

Location

Cylinder Head

Gasket

(2)

™

ST-4

Safety

Valve

Cylinder Head

Cooling

Plate

Valve Plate

Assembly

Cylinder Head Cap Screws (6)

(includes washers)

Return Spring

Balance Piston

Unloader Piston

Assembly

Alignment

Bushings

Unloader Cover

Cap Screws Unloader

Cover

Unloader Cover

Gasket

Balance

Piston

O-Ring

Inlet Reed Valve/

Gasket

Cover

Crankcase

CYLINDER HEAD GASKET KIT PIECE NO. K023764 CONSISTS OF THE FOLLOWING:

ITEM QTY DESCRIPTION

1 1 INLET REED VALVE GASKET 2 2 CYLINDER HEAD GASKET

UNLOADER KIT PIECE NO. K046477 CONSISTS OF THE FOLLOWING:

ITEM QTY DESCRIPTION

3 1 RETURN SPRING 4 1 UNLOADER COVER GASKET 5 1 BALANCE PISTON 6 1 BALANCE PISTON O-RING 7 1 UNLOADER PISTON ASSEMBLY 8 1 LUBRICANT (NOT SHOWN)

Crankcase

Alignment Pins

End Cover

Screws

End Cover

O-ring

SAFETY VALVE KIT PIECE NO. 800534 CONSISTS OF THE FOLLOWING:

ITEM QTY DESCRIPTION

™

9 1 ST-4

SAFETY VALVE

CRANKCASE SEAL KIT PIECE NO. K051352 CONSISTS OF THE FOLLOWING:

ITEM QTY DESCRIPTION

10 1 END COVER O-RING 11 1 COVER

FIGURE 9 – BA-921® CLOSED ROOM COMPRESSOR EXPLODED VIEW.

8. Gently tap the cylinder head, cooling plate and valve plate assembly with a soft mallet to break the gasket seals. Then separate the cylinder head from the cooling plate and valve plate assembly and remove the two gaskets (2) between them.

CRANKCASE FRONT COVER

1. Remove the cover (1 1) from the front of the crankcase. Use a sharp ﬂ at head screw driver or a scraper. Place the edge under the lip along the outside diameter of the cover. Pry the cover from the cast surface until the cover can be removed.

REAR END COVER

1. Note: There are two cap screws used to retain the end cover to the crankcase. There are two longer cap screws (not shown in Figure 10) that are used to retain the auxiliary drive unit (i.e. hydraulic pump) via the end cover and torqued into the crankcase. If the auxiliary drive unit has already been removed, these two cap screws are no longer present on the end cover. Refer

to Figure 9 to see location of the cap screws in the end cover.

2. Remove the two end cover cap screws that secure the rear end cover to the crankcase.

3. Remove the rear end cover from the crankcase. Remove and discard the o-ring (10) from the end cover.

CLEANING OF PARTS GENERAL

All parts should be cleaned in a good commercial grade of solvent and dried prior to inspection.

CRANKCASE

1. Carefully remove all sealant gasket material adhering to the machined face of the crankcase. See Figure

3. Make certain not to scratch or mar the mounting surface. Note: Keep the crankcase opening covered to prevent any of the sealant material from entering. Repeat this process on the engine mounting face as well. Follow the instructions contained in the vehicle maintenance manual in lieu of the instructions and procedures presented in this manual.

2. Carefully remove all gasket material adhering to the deck (top) of the crankcase. Remove any carbon deposits from the deck of the crankcase. Make certain not to scratch or mar the gasket surfaces.

CYLINDER HEAD ASSEMBLY

1. Carefully remove all gasket material adhering to the cylinder head, cooling plate, valve plate assembly and cast iron crankcase. Make certain not to scratch or mar the gasket surfaces. Pay particular attention to the gasket surfaces of the head.

2. Remove carbon deposits from the discharge and inlet cavities of the cylinder head, cooling plate and valve plate assembly. They must be open and clear in both assemblies. Make certain not to damage the head.

3. Remove rust and scale from the cooling cavities and passages in the cylinder head, cooling plate and valve plate assembly and use shop air to clear debris from the passages.

4. Check the threads in all cylinder head ports for galling (e.g. abrasion, chaﬁ ng). Minor thread chasing (damage) is permitted.

5. Remove any carbon or old grease from the two bores in the unloader cavity of the cylinder head.

INSPECTION OF PARTS CYLINDER HEAD, COOLING PLATE, VALVE

PLATE A SSEMBLY AND UNLOADER MECHANISM

1. Carefully inspect the head gasket surfaces on the cylinder head for deep gouges and nicks. Also, inspect the cylinder head for any cracks or port thread damage. If detected, the compressor must be replaced. If large amounts of carbon build-up are present in the discharge cavity, such that it restricts the air ﬂ ow through the cylinder head, the compressor should be replaced.

2. Carefully inspect both sides of the head gasket surfaces on the cooling plate for deep gouges and nicks. Also, inspect the cooling plate for any cracks or other damage. If cracks or damage are found, the compressor must be replaced.

3. Carefully inspect the valve plate assembly gasket surfaces (both sides) for deep gouges and nicks. Pay particular attention to the gasket surface. An inlet reed valve/gasket (1) is used between the valve plate assembly and crankcase. This gasket surface must be smooth and free of all but the most minor scratches. If excessive marring or gouging is detected, the compressor must be replaced. If large amounts of carbon build-up are present on the two main surfaces, in the two discharge valve holes or between the discharge valve and the discharge seat, the compressor should be replaced.

M8x1.25

Cap

Screws

(Smaller)

FIGURE 10 - REAR END COVER ATTACHMENT BOLTS

M10x1.5

Cap

Screws

(Larger)

4. If the unloader assembly has been removed from the cylinder head, the unloader assembly must be serviced using an unloader kit. (See Maintenance Kits, page 9.)

5. If large amounts of carbon build-up are present on the unloader piston (7) seat or oriﬁ ce or if the return spring exhibits compression set, the unloader components must be replaced with an unloader kit.

6. Carefully inspect the 2 bores in the unloader cavity of the cylinder head for gouges or material transfer. If this is detected, the compressor should be replaced.

REAR END COVER

Visually inspect for cracks and external damage. Check the crankshaft rear bearing diameter in the rear end cover for excessive wear, ﬂ at spots or galling. Check the hydraulic pump attachment pilot and threaded holes for damage. Minor thread chasing is permitted, but do not re-cut the threads. If any of these conditions are found, replace the compressor.

CRANKCASE

Check the cylinder head gasket surface on the deck (top) of the crankcase for nicks, gouges, and marring. A metal gasket is used to seal the cylinder head to the crankcase. This surface must be smooth and free of all but the most minor scratching. If excessive marring or gouging is detected, the compressor must be replaced.

Check the condition of the countersunk hole on the deck of the crankcase that retains the o-ring and prevents coolant leakage between the valve plate assembly and the crankcase. The surface in contact with the o-ring should be smooth and free of any scratches and gouges that could causes leakage around the o-ring.

ASSEMBLY

General Note: All torques speciﬁ ed in this manual are assembly torques and typically can be expected to fall off after assembly is accomplished. Do not re-torque after initial assembly torques fall unless instructed otherwise. A compiled listing of torque speciﬁ cations is presented on page 13.

INCH POUNDS TO FOOT POUNDS

To convert inch pounds to foot pounds of torque, divide inch pounds by 12.

Example: 12 Inch Pounds = 1 Foot Pound

FOOT POUNDS TO INCH POUNDS

To convert foot pounds to inch pounds of torque, multiply foot pounds by 12.

Example: 1 Foot Pound x 12 = 12 Inch Pounds

CRANKCASE FRONT COVER

1. Position the new cover over the hole in the front of the crankcase. Using a rubber mallet, drive the cover into the hole in the front of the crankcase, until the outside diameter of the cover is ﬂ ush with cast surface.

REAR END COVER

1. Install the o-ring (10) on the rear end cover.

2. Orient the rear end cover to the crankcase using the reference marks made during disassembly. Carefully install the rear end cover in the crankcase making certain not to damage the crankshaft bearing surface.

3. Install the two end cover cap screws. Refer to Figure

10 to assure that the two cap screws are installed in the proper crankcase bolt holes. “Snug” the screws

then tighten to 195 to 212 inch pounds (22-24 N•m).

CYLINDER HEAD ASSEMBLY PART ONE: HEAD INSTALLATION

1. Note the position of the protruding alignment pins on the deck (top) of the crankcase. Install the metal inlet reed valve/gasket (1) over the alignment pins on the crankcase.

2. Position the valve plate assembly on the crankcase so that the alignment pins in the crankcase ﬁ t into the corresponding holes in the valve plate assembly.

3. Position and install one of the embossed metal gaskets (2) over the alignment bushings protruding from the cooling plate. Position and install the second embossed metal gasket (2) over the alignment bushings on the opposite side of the cooling plate. When properly installed, the outline of the two embossed gaskets match the outline of the cooling plate.

4. Install the cooling plate onto the valve plate assembly by lining up the alignment bushings on the cooling plate over the oversized countersunk holes of the valve plate assembly . Again, when properly installed, the outline of the cooling plate matches the outline of the valve plate.

5. Position and install the cylinder head over the alignment bushings protruding from the cooling plate. When properly installed, the outline of the cylinder head assembly will match the outline of the cooling plate and valve plate assembly.

Note: The alignment bushings will only ﬁ t into two of

the cylinder head bolt holes.

6. Install the six hex head cylinder head bolts and washers and snug them (ﬁ nger tight), then torque the bolts in the sequence speciﬁ ed in Figure 11. Note: A light ﬁ lm of oil should be applied to the thread of these bolts prior to installation. Oil should not be applied to any other bolts.

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