Compressed Air System - General Information
B3.9 and B5.9 Series Engines
Section 12 - Compressed Air System - Group 12
If the air system pressure is not maintained on the discharge valve during unloaded operation, air will be pumped out
of the compressor cylinder, causing a low-pressure (vacuum) condition to form in the cylinder. With the intake valve
sealed off by the unloader cap and the exhaust valve being a one-way pressure actuated valve, no air will be allowed
to enter the cylinder. When the compressor cylinder pressure falls below crankcase pressure, oil will be drawn past
the piston rings and pumped into the air system.
Other brands of compressors can be used on B Series engines. Troubleshooting procedures are very similar for these
air compressors compared to the Holset SS296. Refer to the specific air compressor manufacturer's manual for
detailed repair information and torque specifications.