Kolehamilton Posted February 17 Share Posted February 17 We had a line break on this truck 2 weeks ago, we replaced it and it would stay at 130 PSI, yesterday it started building to 150PSI, we changed the governor it built to 50 PSI temporarily now no air. I was thinking there’s an obstruction. The mechanic has gone over everything and said he found no leaks or obstructions. I’m going to head there to see if I can figure it out, I’m thinking the unloader valve was stuck closed now it’s stuck open? Didn’t know if anyone else might have different ideas? Quote Link to comment https://www.bigmacktrucks.com/topic/73873-mack-was-building-air-to-150-psi-now-it-won%E2%80%99t-go-past-40-psi/ Share on other sites More sharing options...
Kolehamilton Posted February 17 Author Share Posted February 17 Sorry forgot some details Mack 2013 Cxu613 mp8 Quote Link to comment https://www.bigmacktrucks.com/topic/73873-mack-was-building-air-to-150-psi-now-it-won%E2%80%99t-go-past-40-psi/#findComment-546780 Share on other sites More sharing options...
Joey Mack Posted February 17 Share Posted February 17 I would put my money on hard discharge pipe coming off the compressor.. They clog up with carbon... PITA to replace.. unhook the far end of it and start the engine, i bet flow will be low. jojo 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73873-mack-was-building-air-to-150-psi-now-it-won%E2%80%99t-go-past-40-psi/#findComment-546786 Share on other sites More sharing options...
Kolehamilton Posted February 19 Author Share Posted February 19 Sprayed WD40 into the compressor intake and blew air into it with a shop compressor. It’s building now. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73873-mack-was-building-air-to-150-psi-now-it-won%E2%80%99t-go-past-40-psi/#findComment-546855 Share on other sites More sharing options...
fjh Posted February 29 Share Posted February 29 On 2/19/2024 at 8:08 AM, Kolehamilton said: Sprayed WD40 into the compressor intake and blew air into it with a shop compressor. It’s building now. Good job! The unloader on these used to stick common issue! You can buy a head replacement kit for the single cyl compressor! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/73873-mack-was-building-air-to-150-psi-now-it-won%E2%80%99t-go-past-40-psi/#findComment-547386 Share on other sites More sharing options...
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