R and M Diesel Truck Air Compressor Service
Short drive from down town Little Rock, Arkansas
Close to I-30 and I-530.
In order to test the inlet and discharge valves and the unloader piston, it is necessary to have shop air pressure and an assortment of fittings.
A soap solution is also required.
1. With the engine shut off, drain ALL air pressure from the vehicle.
2. Disconnect the inlet and discharge lines and remove the governor or its line or adapter fitting.
3. Apply 120-130 psi shop air pressure to the unloader port and soap the inlet port. Leakage at the inlet port should not exceed 50 sccm.
4. Apply 120-130 psi shop air pressure to the discharge port and then apply and release air pressure to the inlet port.
Soap the inlet port and note that leakage at the inlet port does not exceed 20 sccm.
If excessive leakage is noted in Tests 3 or 4, replace or repair the compressor.
While it is possible to test for inlet, discharge, and unloader piston leakage, it may not be practical to do so. Inlet and discharge valve leakage can generally be detected by longer compressor build-up and recovery times. Compare current compressor build-up times with the last several recorded times. Make certain to test for air system leakage, as described under In Service Operating Tests, before making a determination that performance has been lost.
Unloader leakage is generally exhibited by excessive compressor cycling between the loaded and unloaded condition.
With service and supply system leakage below the maximum allowable limits and the vehicle parked, bring system pressure to governor cut-out and allow the engine to idle.