Air compressor pressure relief valve problem

#1

My air compressor has a valve screwed into the main tank manifold appearing identical to the one in the link below. With the spring inside, and what looks like an adjusting lock nut, and the knurled surface on the other part. I was using compressed air to clean my lawn mower’s engine fins of debris, and the compressor was cycling as normal, turning on at 75 psi and off at 100 psi. I had stopped using the compressed air and was working on something else, but before I stopped w/the compressed air spraying I noticed the tank pressure was 85 psi. The compressor motor hadn’t been running for 10 minutes, when all of a sudden “pop-whoosh” and the compressor tank loses all of its air.

Traced it down to what I think is the pressure relief valve, as described above. It just decided it didn’t want to hold pressure anymore I guess. Anybody else ever have this problem of the compressor’s valve blowing for no reason, and what should I do about it? I tried just plugging the compressor back in once all the air was gone, but the valve was still leaking when I plugged the motor back in again for a test. So what’s up with that? Can this valve be cleaned out and somehow put back into service? Or do I have to purchase a new one?

#2

Play it safe and replace the valve.

#3

I’d just replace it. Amazon has a whole slew to pick from for under $10.

#4

I’ve ordered a replacement part from Grainger. I looked at the old one more closely over the weekend. When I unscrewed it originally, only the threaded portion and the spring came out. Another part or parts remained inside the hole, which I couldn’t get out. What I thought was a steel ball turned out to be an aluminum cup remaining inside. Aluminum, magnet didn’t work to extract it. The only way I could figure to get it out was to turn on the compressor and blow it out. Fortunately, that worked.

Along w/the cup, there was some reddish gunk inside that hole. I think that gunk is what caused it to fail to seal, may have caused the cup to get a little cock-eyed in the hole, resulting in the pop-whoosh effect. Not sure if that gunk is rust or a disintegrated gasket. Anybody here have experience with the cup & spring style of pressure relief valve for air compressors? Is the seal made just between the edged of the cup and the bottom of the hole? Like when you accidentally place an upside down bowl over the kitchen sink drain and it seals so tight the water won’t drain out? Or is there a gasket similar to a faucet washer that’s supposed to be at the end of the hole and the cup seats against that?