2006 387 c-15 air compressor continues to purge air!!!

I called there for prices on a dryer assembly or purge valve and he asked questions as to why and he suggested trying the unloader valve. No different than taking your advice or anyone else's. Besides he's a excellent parts guy.

 

In all my years of trucking, I've never had an unloader valve go out. I've had plenty of purge valve stick opened or leak. Hope it fixes your problem. Be sure a let us know for the next guy with this problem.

 

Defective unloaded valve would cause the safety valve to pop open but not the purge valve to leak IMO. Have you already replaced the governor?

 

Here's my 2cents,and experiance!Had this happen I time,and it ended up being the little brass valve screwed into the side of the compressor,you'll probably have to get it at a cat dealer,but a good pb dealer should have it...

 

just had the same problem, replace the purge valve, problem will be solved. if it leaks after it purges the purge valve isn't closing all the way, they get gunked up. if you cant get it out after removing the snap ring, start the truck , when it purges it will shoot right out.

changed mine today on 06 kw with bendix dryer part number 801266, purge valve assembley is part number k022105 for that dryer

 

i had simular issues last Saturday. I've even had air leaking off the head of the compressor, as long as it was in the Not Loading Stage. The mechanic took the lid of the unloader valve and found the piston had a light sign of wear where the O-Ring sits. Since parts were not available on Sunday, he just put a slightly thicker O-Ring in and put things back together. It still builds up pressure every 2.5 minutes but at least it shut the noisy airdryer silent. $88 seems to be a reasonable amount for that repairkit.

 

OK so I replaced the unloader valve and it stopped pumping air like it was suppose to after the pressure building cycle was complete and finally no more poof poof noise out of the purge valve from the compressor continuing to pump air. About 7000 miles later I noticed my compressor became slow to "load" or begin to build pressure. Like it would start to build for a second and stop or the unloader valve would release so you could here it begin to work the compressors but the purge valve wasn't closing at the cut in. I also noticed the cutout pressure was fluctuating quite a bit from one cycle to the next also I found a slight air leak at the governor when the truck was off. So when I went to replace that and took it apart the oring on the check valve body was no where to be found. But I replaced the governor and the check valve with the oring. Supplied in the kit and so far it has been operating flawlessly!! So did I have two problems at the same time its possible. The oring on the unloader valve did look and feel old and brittle after all the truck did have 987,000 miles. And the unloader valve i used to replace it from cat was the newer updated one of a slightly different design. Thanks for the help and I hope this helps the next guy.