HEAD GP-PUMP 2959660 - Caterpillar

Removal of the Unloader Piston
Ensure that the proper repair kit is available prior to the removal of the unloader piston. The air compressor has a service kit for the unloader piston. The service kit includes the gasket for the unloader cap, the unloader piston, the spring for the balance piston, the balance piston, and the rubber O-rings.Note: It is not necessary to remove the air compressor cylinder head in order to remove the unloader piston. Refer to the procedure below for removal of the unloader piston.
Illustration 1 g01263489
(1) Screw (unloader cap) (2) Unloader cap (3) Gasket (unloader cap) (4) Balance piston (5) Spring for the balance piston (6) O-ring (7) Unloader piston (8) O-ring (9) O-ring (10) Bore for the unloader piston (11) Cylinder head
Hold the unloader cap (2) in place. Remove the screws (1) for the unloader cap. The unloader cap (2) will have spring pressure against the cap. Carefully remove the unloader cap (2). Remove the gasket (3) for the unloader cap (2). Clean the old gasket material from the unloader cap (2). Discard the gasket (3) .
Remove the balance piston (4) and the spring (5). Discard the balance piston (4) and the spring (5) .
Remove the unloader piston (7) and the O-rings (6), (8), and (9). Discard the unloader piston (7) and the O-rings (6), (8), and (9) .
Check the bore (10) for the unloader piston (7). Use a flashlight to check for any damage to the intake reed valve/gasket and/or damage to the top of the piston for the air compressor. If damage is present the air compressor must be replaced.