ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 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. For applications fitted with selective catalytic reduction exhaust systems, check the air supply line to the dosing control unit.


Air governor is malfunctioning or not set correctly

Check the air governor for correct operation. Refer to the OEM service manual.


Air compressor intake or exhaust valve leaks air

Inspect the air compressor intake and exhaust valve assemblies. Refer to the OEM service manual.

Last Modified:  06-Oct-2006