TM 5-3810-30024 & P2
Check for noisy compressor operation, which could indicate a worn drive gear coupling or a loose pulley. Adjust and/or
replace as necessary. Check all compressor mounting bolts and retighten evenly if necessary. Check for leakage and
proper unloader mechanism operation. Replace if defective in any way.
EVERY 24 MONTHS, 7200 OPERATING HOURS OR AFTER EACH 200,000 MILES.
Perform a thorough inspection as indicated below and depending upon the results of this inspection or experience,
disassemble the compressor, clean and inspect all parts thoroughly, repair or replace all worn or damaged parts using only
genuine Bendix replacements or replace the compressor with a genuine Bendix remanufactured unit.
IMPORTANT - Should it be necessary to drain the engine cooling system to prevent from freezing, the cylinder head of the
compressor must also be drained.
GENERAL SERVICE CHECKS.
INSPECTION.
It is of the utmost importance that the compressor receives a clean supply of air. The air strainer must be properly
installed and kept clean. If the compressor intake is connected to the engine air cleaner, supercharger, etc., these
connections must be properly installed and maintained. Check the compressor mountings to be sure they are secure.
Check the drive for proper alignment, belt tension, etc.
Inspect the oil supply and return lines. Be sure these lines are properly installed and that the compressor is getting the
proper supply of oil, and just as important, that the oil is returning to the engine. Check the coolant lines to and from the
compressor and see that the cooling fins on the crankcase are not clogged with dirt, grease, etc. Check the unloader
mechanism for proper and prompt operation.
OPERATING TESTS.
Vehicles manufactured after the effective date of FMVSS 121, with the minimum required reservoir volume, must have a
compressor capable of raising air system pressure from 85-100 P.S.I. in 25 seconds or less. This test is performed with
the engine operating at maximum governed speed. The vehicle manufacturer must certify this performance on new
vehicles with appropriate allowances for air systems with greater than the minimum required reservoir volume.
TROUBLESHOOTING
Compressor Fails to Maintain Adequate Pressure in the Air Brake System.
Dirty intake strainer.
Excessive carbon in compressor cylinder head or discharge line.
Discharge valves leaking.
Excessive wear.
Drive belt slipping.
Inlet valves stuck open.
Excessive leakage of inlet valves.
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