Air Compressor Pin Bore Wear (SS,
E-Type, and ST Models) (012-010)
Initial Check (012-010-001)
The unloader valve body is installed with
spring tension. Use care when removing to
prevent personal injury. Always wear
protective eye wear.
Hold the unloader valve body down and remove the two
captive washer capscrews and the two plain washers.
Remove the unloader valve body.
Remove the 0-ring seal.
Remove the rectangular ring seal.
Remove the unloader valve cap and the unloader valve
Disassembly of the center unloader valve on
Holset two cylinder air compressors is similar
to the single cylinder unloader valve.
Remove the intake valve seat and valve.
Remove the intake valve spring.
To avoid damage to the air compressor, do not allow
any debris to fall into the air compressor cylinder.
Do not use a screwdriver. A screwdriver can
gouge the top of the piston.
Insert the small end of a 3/8 inch drive socket extension
(6 to 10 inches long) through the exhaust valve seat
onto the top of the piston.
Bar the crankshaft over until the compressor piston
reaches top dead center (TDC), and the extension starts
to move downward approximately 3 to 6 mm [1/8 to 1/4