Hey folks, new the the site. i have a 2010 Thomas Saftliner HDX i am working on. it has a 6.7L cummins, flywheel mounted air compressor, remote mounted governor. originally it started out as repairing a couple air leaks, from brake valve, and brake chamber. then it would build air when first started, would purge at approx 130psi, and then be real show to build after. it then went to not building at all after purge, and now absolutly nothing. at high idle there is a fluttering sound coming from the compressor, im thinking that is the unloaders. i removed the unloader line going from the governor to the compressor and connected shop air to it, approx 100 psi, expecting the air to leak through, after 2 hours connected it hadnt dropped at all. so with the unit running i climbed under and removed the air feed line to the dryer from the compressor, absolutely no air coming through. i am seeking additional advise on further troubleshooting before i go ahead and replace the compressor. maybe i didnt troubleshoot properly? please let me know thanks.
What kind of air compressor is it ? What model? If it is a wabco they offer a replacement cyclinder head for them as far as i know they do not have a servicable unloader like bendix. I have never used a replacement head its less trouble to replace the whole compressor no one stocks the wabco head ever it seems in my experience. Re reading your post it takes air pressure to unload compressor , if you have no air pressure at unloader port of cylinder head ot should be pumping air if it is not the unloader is sticking.