Procedure to Update the Head Gasket on the Air Compressor on Caterpillar On-Highway Engines{1803, 7555} Caterpillar


Procedure to Update the Head Gasket on the Air Compressor on Caterpillar On-Highway Engines{1803, 7555}

Usage:

C7 C7S
Engine:
C7 (S/N: C7S1-UP)
C9 (S/N: C9S1-UP)
C11 (S/N: KCA1-UP)
C13 (S/N: KCB1-UP; LEE1-UP)
C15 (S/N: SDP1-UP)

Introduction

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

Reason for the New Head Gasket

Some issues have been occurring with the current head gasket on air compressors. The head gasket is allowing compressed air to enter the cooling system. New metal head gaskets are now used to prevent the compressed air from entering the coolant system.

Procedure to Replace the Head Gasket

Table 1
Required Parts    
1     6L-1883 Gasket    
2     6V-6609 O-Ring Seal    
1     6V-1903 O-Ring Seal    
2     2M-9780 O-Ring Seal    
1     307-6209 Cylinder Head Kit    

Note: The 307-6209 Cylinder Head Kit contains a new cylinder head assembly, a new head gasket, and six new cylinder head bolts.

Cylinder Head Removal

  1. Purge the air system to less than 620 kPa (90 psi).

  1. Drain the vehicle's coolant system.

  1. Disconnect the air and coolant lines from the fittings that mate on the compressor.

  1. If the engine has a governor then remove the governor. Also remove the fittings that mate and the pressure relief valve on the head of the compressor. These parts will be used on new cylinder head assembly. Do not discard these parts.

  1. Loosen the six head bolts. Remove the six head bolts and discard the bolts.

    Note: Note the orientation of the cylinder head ports to the engine.

  1. Remove the cylinder head assembly from the cylinder block. If necessary, tap the head assembly lightly with a plastic mallet in order to assist loosening of the head assembly from the cylinder block.

  1. Remove the gasket from the top of the cylinder block and discard the gasket.

Cylinder Head Installation

  1. Make sure that the top of the cylinder block is clean and dry.

  1. Retrieve the new cylinder head gasket, cylinder head assembly and head bolts.

  1. Oil the threads of the head bolts with 15W40.

  1. Install two head bolts into the new cylinder head assembly.

  1. Install the head gasket over the two head bolts until the gasket is flush with the bottom surface of the cylinder head assembly.

  1. While holding the gasket against the cylinder head assembly and the two bolts against the cylinder head, orient the cylinder head and the head gasket assembly onto the cylinder block in the same orientation as the original cylinder head. Align the two head bolts in the thread holes of the cylinder block.

  1. Hand tighten the two head bolts.

  1. Install the four remaining head bolts and hand tighten the bolts.



    Illustration 1g01378326

    The tightening sequence for the head bolts on the Air Compressor

  1. Torque the six head bolts to the sequence in Illustration 1.

    1. Tighten the bolts to 42 ± 5 N·m (30.9775 ± 3.6878 lb ft) in order to burnish the bolts.

    1. Loosen the six head bolts.

    1. Tighten the six head bolts to 14 ± 1 N·m (10 ± 1 lb ft) in the proper sequence in Illustration 1.

    1. Tighten the six head bolts 120°. Loosen the bolts 2° in sequence. Tighten the bolts 4° in the proper sequence.



    Illustration 2g01378365

    Tightening sequence for the Unloader bolts

  1. Torque the unloader bolts to 12 ± 3 N·m (106 ± 27 lb in) in the sequence that is shown in Illustration 2.

  1. Reinstall the governor, the new governor gasket, the fittings that mate, and the pressure relief valve. Make sure in order to install the pressure relief value to the original position on the cylinder head on the air compressor.

    Note: Use the new seal O-rings when you install the pressure relief valve.

  1. Connect the air lines and the coolant lines to the appropriate fitting on the cylinder head.

  1. Refill the vehicle's coolant system.

Operational Check

After all repairs are completed and air lines are connected, then start the engine. Build up the air pressure in the system until the system cuts out pressure. Shut off the engine. Check for air leaks from the interface of the governor to the air compressor. Also check for air leaks at the outlet. The outlet is port number 2 on the air compressor. Check for coolant leaks at the cylinder head and check the interface of the cylinder block and fittings for leaks. Correct any leaks that may be found.

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