Cat Compressor / Bendix Air Dryer

[Preacher]

My air dryer is cycling every minute or so. Air guages show air pressure is fine (no drop in psi) when applying the brakes, even when holding the pedal down for up to 3 minutes with the motor on or off. But guages show 3-5psi drop in 1 minute when engine is running/idling with no brakes applied. This is causing the compressor to be over worked. It pumps the pressure right back up to 120psi which causes the air dryer to cycle. Can't hear any obvious leaks except at the pressure release valve on the compressor. (slight hissing sound) Also, air pressure drops when engine is off from 120 to around 60psi after only 30 minutes.

Any ideas anybody? :noclue:

[Preacher]

I answered my own question. It was the Bendix air pressure pop valve at the compressor. It wasn't seating properly. A new one fixed the problem. :D