Using the Air Compressor Unloader Kit for On-Highway Engines{1803} Caterpillar

Engine:

C11 (S/N: KCA1-UP)

C13 (S/N: KCB1-UP; LEE1-UP)

C15 (S/N: SDP1-UP)

C7 (S/N: C7S1-UP)

C9 (S/N: C9S1-UP)

Introduction

Do not perform any procedure in this Special Instruction until you read this information and you understand this information.

Safety Section

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Personal injury can result from being struck by parts propelled by a released spring force. Make sure to wear all necessary protective equipment. Follow the recommended procedure and use all recommended tooling to release the spring force.

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Personal injury can result from removing hoses or fittings in a pressure system. Failure to relieve pressure can cause personal injury. Do not remove or disconnect hoses or fittings until all pressure in the air system has been relieved.

Required Parts

Use the 335-6328 Unloader Kit (AIR COMPRESSOR) .

Preparation of Vehicle

These general instructions are intended to be a guide. In some cases, additional preparations and precautions are necessary. In all cases, follow the instructions and precautions contained in your vehicle's maintenance guide instead of the information found in this document.

Installing the Unloader Kit

Illustration 1	g01865456
(1) Return Spring (2) Gasket (3) Balance Piston (4) O-ring (5) ESS Piston Assembly

Note: Two kits are required to service two cylinder compressors.

1. Read the statement under the heading of PREPARATION of VEHICLE.

2. Locate the two screws that secure the unloader cap to the cylinder head. Clean the area in order to prevent any contamination from entering the bore of the unloader.

3. The unloader cap must be held in place while removing the two screws in order to restrain the spring force that is exerted by the spring (1) of the balance piston. Carefully release the hold on the unloader cap. Remove the splash shield for the single cylinder compressor.

   Note: Retain the original unloader caps and the splash shield. These parts will be reused.

4. Remove the cover gasket (2) of the unloader. Discard the gasket.

5. Remove balance piston (3). Remove the O-ring (4) of the balance piston. Remove the spring (1) from the cylinder head. Remove the unloader piston (5) and the accompanying O-rings (5) .

6. Clean the bore of the unloader piston in the cylinder head. Inspect the bore. If any damage in the form of scratches, galling, or significant wear is present, then the entire cylinder head must be replaced. Use the Bendix PN K023600 or K023601 head kit.

7. The service kit contains a piston assembly for the unloader that is preassembled. An O-ring must be installed on the balance piston. The O-ring for the balance piston is brown in color. Take special care to thoroughly lubricate the O-rings. Do not twist or pinch the O-rings during installation. If an O-ring appears to have a twist, then manipulate the O-ring in order to remove any twists.

   Use the provided lubricant to thoroughly lubricate the O-ring and install the O-ring on the bore of the unloader piston. Remove the unloader piston,guide bushings, and O-rings from the package. Remove the plastic cap from the top of the piston. Ensure that the entire exterior of the piston is thoroughly lubricated. Additional lubricant should be applied between the upper O-ring and the lower outside O-ring. Lubrication of the balance piston, unloader piston, and the bore should consume the entire packet of lubricant. Insert the piston assembly for the unloader (5) into the cylinder head. Take care to avoid catching the edge of the guide bushings on the bore of the unloader piston. If significant resistance is encountered, then remove the unloader piston and adjust the position of the bushing. Retry. Press on the upper guide bushings with your fingers while inserting the unloader piston into the bore can be helpful.

   Note: The O-ring for the balance piston is brown and the O-rings that are installed on the outside of the unloader piston are black.

8. Insert the spring (1) into the unloader piston (5) .

9. Lubricate the balance piston (3). Insert the end of the balance piston with the smaller diameter into the spring (1) that was previously installed in the unloader piston (5) .

Note: The original unloader caps should be reused in order to service the compressors. Discard the unloader caps that are supplied with the service kit. For the single cylinder compressor, also reuse the splash shield.

10. Clean any gasket material from the unloader cap. A narrow machined slot is present in the single cylinder compressor. Remove any debris that is present in the slot.

11. Position the gasket for the unloader cap (2) on the cylinder head. If necessary, position the splash shield on the balance piston. Position the unloader cap on the balance piston (3). Ensure that the unloader cap is oriented correctly. Use manual pressure to gently push the balance piston into the unloader piston until the unloader cap rests against the cylinder head. Use the two screws for the unloader cap to secure the unloader cap. Torque the screws to 7 to 8 N·m (62 to 71 lb in).

Returning the Vehicle to Service

1. Ensure that the threads are clean and that the fittings are free of corrosion. If necessary, replace the fittings.

   If necessary, reinstall the UN-2B fittings for the inlet port.

   Straight fitting ... 95 to 104 N·m (841 to 920 lb in)

   Adjustable fitting with jam nut ... 67 to 74 N·m (593 to 655 lb in)

   If necessary, reinstall the UNF-2B fittings for the discharge port.

   Straight fitting ... 57 to 62 N·m (504 to 549 lb in)

   Adjustable Fitting with jam nut ... 40 to 44 N·m (354 to 389 lb in)

   If necessary, reinstall the UNF-2B fittings for the water port.

   Straight fitting ... 30 to 33 N·m (265 to 292 lb in)

   Adjustable fitting with jam nut ... 28 to 31 N·m (248 to 274 lb in)

   If necessary, reinstall the fittings for the unloader port. ... 2 to 3 turns from finger tight

   If necessary, reinstall the safety valve. ... 26 to 29 N·m (230 to 257 lb in)

   If necessary, reinstall the oil port. ... 17 to 19 N·m (150 to 168 lb in)

2. Before the vehicle is returned to service, the Operation and Leaking Tests that are specified below must be performed. Pay particular attention to all lines and check for oil, air, and coolant leaks at the connections of the compressor. Check for noisy operation. Repair the components or replace the components, if necessary.

Operation and Leakage Tests

1. Start the engine and note that the air system steadily builds pressure.

2. While the system air pressure increases check the cylinder head gasket for air leakage. Apply a soap solution around the cylinder head. Check the gaskets between the cylinder head, the cooling plate, and the valve plate assembly for air leakage. No leakage is permitted. If leakage is detected, drain all air pressure and torque the head bolts. if replacing the head gasket has not resolved the leakage problem, then the compressor must be replaced.

3. Allow the buildup of the air pressure of the system. Confirm that the compressor unloads properly at the specified governor cutoff pressure. Repeat this test three times. Confirm that the compressor unloads at approximately the same pressure each time. If the compressor fails to unload by the minimum of 1034 kPa (150 psi) system pressure, then check all lines to the governor and from the governor. Ensure that all the lines have the following qualities: unobstructed, without kinks and not leaking. Repair the governor or replace the governor, if necessary.