Original post by: Herbert ,
Had the same problem, turned out to be the line from the governor. The one that sends the signal, had a small hole from where it had rubbed on a bracket. It will only leak when it is trying to send a signal between the air dryer and governor. So it may not be a continuous leak. I replaced my valve on the air dryer and it was continuing to pop. While I was trying to figure what to do next I noticed the air leak when it sent the signal. Not a 100% sure, but my guess is that when the air dryer pops it sends a burst of air back to the governor to stop the air compressor from pumping air. Its cheaper to check the lines than to replace a valve or air dryer.