View Full Version : Air System Leak Problem Need Idea's

06-13-2013, 05:33 PM

I am having trouble with my governor/air dryer. I noticed while going down the road the pressure gauge would occasionally read up to 150psi before the compressor unloaded. I replaced the governor and the compressor shuts off at 120psi but now I notice it takes a long time to build pressure, when the pressure is coming up and reaches about 100psi the purge valve begins to leak, at 120psi the compressor unloads and the leak at the purge valve continues until the pressure reaches about 100psi then stops when the compressor starts. This goes on while driving taking about 5 to 10 minutes to cycle. I replaced the purge valve with no change. I then reinstalled the old governor and adjusted it to unload at 120psi, I still have the leak at the purge valve but the leak stops (still about 100psi) before the governor starts the compressor so I do not have the cycling. Any thoughts?



06-13-2013, 09:18 PM
Phil: this is a SWAG but if the leaky purge valve was not present prior to the 150PSI exposure and since you have demonstrated that neither the purge valve itself nor the governor are causing this by having changed them with no change in symptoms I would be suspecting something in the drier got distorted by the excessive pressure, probably where the active part of the purge valve seals to the housing. I would check if there is any interaction between the purge valve and the drier other than letting air out the vent. If there isn't then what I suggested above is all I could think of.

06-13-2013, 09:37 PM
Phil: one more thought. There is a check valve in the outlet of the dryer that is intended to prevent backflow of compressed air from the reservoir once the governor cuts off the compressor. Since it seems you have some compressed air coming out with the compressor off that check valve has to be leaking and draining the reservoir pressure. If it was just the purge valve the leak would only occur while the compressor was running. You may have two problems, a distortion where the purge valve is and a bad check valve. Ready for the trifecta?

06-15-2013, 01:21 AM
Maybe Your ball check valve is stuck open

06-15-2013, 03:27 PM
Purge valves on air dryers also need to be replaced/rebuilt on air dryers periodically in addition to replacing the desiccant cartridge. Something to think about, Sean