Shut off the engine.
Open the draincock on the wet tank to release air from the system. Close the draincock after the pressure is
released.
Operate the engine to activate the air compressor.
With the air compressor pumping between 550 to 690 kPa [80 to 100 psi], use a solution of soapy water to check for
air leaks in the following areas:
โข Unloader cover gasket
โข Unloader pin o-ring
โข Air compressor head gasket.
For the QSB3.9-30, QSB4.5-30, and QSB5.9-30 engines, if air leaks are found, refer to Procedure 012-013 in the
Troubleshooting and Repair Manual, QSB3.9-30, QSB4.5-30, and QSB5.9-30 Industrial Engines, Bulletin
4021398, for repair of these components.
For the ISB and QSB5.9 engines, if air leaks are found, refer to Procedure 012-013 in the Troubleshooting and Repair Manual ISB and QSB5.9 Engines, Bulletin 3666193, for repair of these components.
