Service Manual

Air Compressor Cylinder Head, Single Cylinder ISB, ISBe and QSB (Common Rail [...]
Page 12-14 Section 12 - Compressed Air System - Group 12
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Inspect the cylinder head for signs of coolant leaks. A
coolant leak can be recognized by looking for places
where the engine paint on the compressor has been
washed away. White crystalline clusters of material are
not a sign of a coolant leak.
If a coolant leak is found, the cylinder head should be
rebuilt using a gasket kit.
Verify the unloader slider plate is fully closed when at rest.
Remove the unloader slider plate and verify proper
unloader piston travel. Use a stiff wood handle or
equivalent non-abrasive device to move the unloader
piston by pushing back on the unloader slider plate guide
pin in the direction of arrow as indicated. Be careful not to
damage the aluminum surface of the head or drop debris
into the open slot in which the guide pin travels.
NOTE: When released, the unloader piston should return
to the loaded position with a quick, smooth motion and
audible snap.
If the unloader piston does not return to the loaded
position with a quick, smooth motion and audible snap,
use the below table for repair direction:
Guide Pin Action Repair Direction
Guide pin can be moved to
loaded (closed) position by
hand.
Spring is broken or weak;
replace cylinder head.
Guide pin does not return
or slow to return to loaded
position.
Refer to Procedure 012-003
in Section 12.
Disassemble
NOTE: Most repairs will not require disassembly of the air
compressor head. Disassembly of the two halves of the
air compressor head is only required in the case of
coolant leaks or excessive carbon build up.
Disassemble the air compressor cylinder head by
removing the five Torx™ head screws.
Discard these screws; they are not reusable and new
screws will be provided in the gasket kit.
Separate the two halves of the cylinder head.
Remove and discard the old gasket.
NOTE: Do not remove the exhaust valve or exhaust valve
capscrews. If the exhaust valve capscrews are removed,
the cylinder head must be replaced.