Procedure to Install a Service Kit for the Unloader for the Air Compressor{1803} Caterpillar

Procedure to Install a Service Kit for the Unloader for the Air Compressor{1803}

Usage:

C-12 2KS

On-Highway Engine:: C-12 (S/N: 8YF1-UP; MBL1-UP; 2KS1-UP); C-15 (S/N: MBN1-UP); C11 (S/N: KCA1-UP); C13 (S/N: KCB1-UP; LEE1-UP; JAM1-UP); C15 (S/N: SDP1-UP; B5R1-UP; BXS1-UP; MXS1-UP; NXS1-UP)

Introduction

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

This Special Instruction has general information and instructions. Use the instructions below as a guide. Some cases, additional preparations and precautions are necessary. In all cases follow the instructions contained in the vehicles Operation and Maintenance Manual as well as the instructions, precautions and procedures suggested in the article that follows.

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Personal injury can result from not following the specified procedure.

To avoid personal injury, follow the procedure as specified.

Preparation of the Vehicle

Block the wheels of the vehicle. Drain the air pressure from all the reservoirs in the air system.

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

Procedure to Install the 260-6822 Unloader Kit

Note: A separate 260-6822 Unloader Kit for the unloader is required for each unloader on the air compressor.

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Illustration 1	g01514736
260-6822 Unloader Kit (1) Screws for the unloader cap (2) Splash shield for air compressors with a single cylinder (3) Unloader cap (4) Gasket for unloader cap (5) Balance piston (6) Spring (7) O-ring (8) Unloader piston (9) O-ring (10) O-ring (11) Cylinder bore for the Unloader (12) Air compressor

Remove any remaining contamination in the area of the air compressor. This will prevent any debris from entering the bore of the unloader.

Note: Make sure in order to apply pressure to the unloader with your hand before proceeding to Step 2. The piston spring (6) under the unloader cap (3) is under pressure. This could force the unloader cap off the air compressor (12) .

Loosen the two screws (1) that secure the unloader cap (3) to the cylinder head of the air compressor (12). Again, remember to apply some pressure to the unloader cap (3) .

Carefully release the hold on the unloader cap until the tension of the spring is released. Then remove the unloader cap. Also remove the splash shield (2) on air compressors with a single cylinder.
Note: Retain the original unloader cap (3) and the splash shield (2), if equipped. These parts will be reused.

Remove the cover gasket (4) for the unloader and discard the gasket.

Remove the balance piston (5) and the spring (6). Discard the piston and the spring from the cylinder head on the air compressor.

Remove the unloader piston (8) and discard the piston. Also remove the three O-rings (7), (9), and (10). Discard the O-rings as well.

Clean the bore (11) for the unloader piston (8) in the cylinder head of the air compressor.

Note: Thoroughly lubricate the O-rings before installation. Also make sure that the O-rings are not twisted or pinched after the O-rings have been installed.

Lubricate the O-rings, and then install the O-rings (7), (9), and (10) on the unloader piston. Use the lubricant that was provided with the service kit.
Note: O-rings (9) and (10) are installed on the outside of the unloader piston. O-ring (7) is installed on the inside diameter of the unloader piston. Refer to Illustration 1 for the location of the O-rings (7), (9), and (10) .

Lubricate the bore (11) for the unloader piston in the cylinder head.

Insert the unloader piston (8) into the cylinder bore. Make sure that the O-rings are installed on the piston before installing the piston.

Insert the spring (6) into the unloader piston.

Lubricate the balance piston (5) and then insert the balance piston into the spring. Illustration 1 shows the proper way to insert the balance piston into the spring. The spring was previously installed in the unloader piston in Step 11.

For compressors with a single cylinder or a twin cylinder, the original unloader caps should be reused on the air compressors. Also reuse the splash shield on compressors with a single cylinder. Discard the unloader caps that are supplied with the service kit.
Make sure that the unloader caps are free of any gasket material. A slot is machined into the unloader caps that are used on compressors that have a single cylinder. Make sure that any debris is removed from that slot.

Position the gasket for the unloader cap on the cylinder head. Position the unloader cap, and splash shield for compressors with a single cylinder, on top of the balance piston (5). Make sure that the cap is oriented correctly.

Use manual pressure in order to gently push the balance piston (5) into the unloader piston (8) until the unloader cap rests against the cylinder head. Use the two screws (1) that were removed in Step 2 in order to secure the unloader cap. Torque the screws to 7 N·m (62 lb in) to 8 N·m (71 lb in).

Returning the Vehicle back to Service

Reinstall any fittings that might have been removed in order to install the service kit. Make sure that the threads are clean and that the fittings are free of corrosion. Replace any fittings, as needed. See the Torque Specifications for various fitting sizes and types of thread.

Perform the Operation and Leakage Test, before returning the vehicle back to service. Pay particular attention to all the lines on the engine. Check for air, oil, and coolant leaks at all the connections on the air compressor. Also check for noisy operation. Repair components or replace components, as needed.

Operation and Leakage Test

Start the engine. Pay close attention to the air system as the system builds air pressure.

Make sure that you check the cylinder head on the air compressor for air leaks, while the air system builds up air pressure. 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 leaks as well. Make sure that the air system, and the air compressor do not have any leaks. If a leak is detected, torque the head bolts. Refer to the Torque Specifications for the proper torque on the cylinder head bolts. Make sure that you release the air pressure from the system before you torque the head bolts. If leaks are still present, then replace the head gasket on the air compressor. Replace the air compressor if replacing the head gasket did not resolve the leak.

Allow the air pressure to increase. Make sure that the air compressor unloads the air pressure properly. Also make sure that the air pressure is unloaded at the specified governor cutout pressure. Repeat this test three times. Make sure that the air compressor unloads the air pressure approximately at the same pressure. Check all the air lines, if the pressure is not released by at least 1 MPa (150 psi). Make sure that each line is not obstructed, kinked, or leaking. Repair the governor or replace the governor, as needed.

Torque Specifications

Cylinder Head

Torque M8 x 1.25 cylinder head bolts to 30 N·m (22 lb ft) to 33 N·m (24 lb ft)

Unloader Cap

Torque M5 x 0.75 unloader cap bolts to 7 N·m (62 lb in) to 8 N·m (71 lb in).

Fitting for the Inlet Port

Torque 1-3/16 inch straight inlet port fitting to 95 N·m (70 lb ft) to 104 N·m (76 lb ft).

Torque 1-3/16 inch adjustable inlet port fitting to 67 N·m (49 lb ft) to 74 N·m (54 lb ft).

Discharge Port Fitting

Torque 7/8-14 inch straight discharge port fitting to 57 N·m (42 lb ft) to 62 N·m (46 lb ft).

Torque 7/8-14 inch adjustable discharge port fitting to 40 N·m (29 lb ft) to 44 N·m (32 lb ft).

Fitting for the Port for the Water

Torque 3/4-16 inch straight water port fitting to 30 N·m (22 lb ft) to 33 N·m (24 lb ft).

Torque 3/4-16 inch adjustable water port fitting to 28 N·m (21 lb ft) to 31 N·m (23 lb ft).

Port Fitting for the Unloader

Just hand tighten the 1/8-27 inch fitting for the unloader port. After the fitting is hand tight, then turn the fitting two or three more turns with a wrench.