Holset Air Compressors Master Repair Manual – Air Compressor Will Not Maintain Adequate Air Pressure (Not Pumping Continuously)

Symptom Tree  t008

This is symptom tree t008
Cause Correction

Air system leaks

Block the vehicle wheels and check the air system for leaks with spring brakes applied and released. Check for leaks from the air compressor gaskets and the air system hoses, fittings, tanks, and valves. Refer to the OEM service manual.


Air governor is malfunctioning or not set correctly

Check the air governor for correct operation. Make sure the air governor is located less than 0.6 m [2 ft] from the air compressor. Refer to Procedure 012-017 or 012-018.


Air compressor intake or exhaust valve leaks air

Inspect the air compressor intake and exhaust valve assemblies. Refer to Procedure 012-101, 012-103, 012-104, or 012-106.


Water cooled air compressor, head or head gasket leaking (if equipped)

Look for coolant in the oil. Check or replace compressor head or head gasket. Refer to Procedures 012-101 and 012-103.

Last Modified:  13-Jun-2005