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ISM, ISMe, and QSM11 – 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 Procedure 012-019 and the OEM service manual.
 

Air governor is malfunctioning or not set correctly

Check the air governor for correct operation. Refer to Procedure 012-013.
 

Air compressor intake or exhaust valve leaks air

Inspect the air compressor intake and exhaust valve assemblies. Refer to the Master Repair Manual, Holset® Air Compressors, Bulletin 3666121.
 

Cover gasket is leaking internally (Holset® SS models only)

Check the torque on the unloader screws. Refer to Procedure 012-013.
 

Air installation issues

Refer to the Automotive and Bus Installation Recommendations – Air Compressor Systems, Bulletin 3884946.
 
Last Modified:  18-Dec-2003
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Hello, I'm Jack, a diesel engine fan and a blogger. I write about how to fix and improve diesel engines, from cars to trucks to generators. I also review the newest models and innovations in the diesel market. If you are interested in learning more about diesel engines, check out my blog and leave your feedback.