Holden kinard Posted October 1 Share Posted October 1 I have a 2004 Mack roll off so where do I start this truck started having trouble building air it started at it would stay at 90 idle then 80 then 70 within 3 months so I replaced the air compressor and air dryer and governor and it wouldn’t build air past 50 idle or on the gas so I got another air compressor saying well maybe I got a bad one no it still won’t I bypassed the air dryer and nothing and bypassed the governor and still nothing this is my only truck I need help guys and it has 760k miles on it Quote Link to comment Share on other sites More sharing options...
mowerman Posted October 2 Share Posted October 2 You about covered everything except air guage good luck Quote Link to comment Share on other sites More sharing options...
Popular Post Geoff Weeks Posted October 2 Popular Post Share Posted October 2 1st hook shop air to the truck, and listen for air leaks. There are so many places air can leak on a modern truck, it is almost a full time job finding and curing the leaks. How long does it take for the air to leak off once you shut down the truck? Next spray the line from the compressor to the air drier and all the way to the wet tank with soapy water, looking for bubbles/foam. Since you replaced the air compressor et all twice I doubt they are the problem, but: Last take the line from the air gov to the compressor off and briefly start the engine and see if air comes out either the port on the compressor or the line from the air gov. Be careful because nothing is going to shut the compressor off if the pressure rises, you just want to make sure, nothing is triggering the unloader. 3 Quote Link to comment Share on other sites More sharing options...
Mark T Posted October 3 Share Posted October 3 I had one once, acted like that. It was the drive gear spun on the auxilary drive. Actually, I had 2 did that. One the compressor seized up and did it, and one just did it. It's only a pressed fit . Geoff is right, air leaks can fool ya too. Seem maybe not so bad, but they'll ruin ya. Quote Link to comment Share on other sites More sharing options...
tjc transport Posted October 3 Share Posted October 3 on the 05 granite it was an air pressure regulator feed line leaking. replaced the line and the next day the compressor threw a rod through the side dumping 3 gallons of oil out before i noticed the oil leak. Quote when you are up to your armpits in alligators, it is hard to remember you only came in to drain the swamp.. Link to comment Share on other sites More sharing options...
Geoff Weeks Posted October 9 Share Posted October 9 Any updates? Quote Link to comment Share on other sites More sharing options...
JoeH Posted Sunday at 12:01 PM Share Posted Sunday at 12:01 PM My bet is a QR valve failed, but would be nice to have an update 2 Quote Link to comment Share on other sites More sharing options...
MACKS Posted Sunday at 02:42 PM Share Posted Sunday at 02:42 PM So when u shut it down does it hold air? Quote Link to comment Share on other sites More sharing options...
MACKS Posted Sunday at 02:44 PM Share Posted Sunday at 02:44 PM More wasted responses..🤔 Quote Link to comment Share on other sites More sharing options...
JoeH Posted Sunday at 09:27 PM Share Posted Sunday at 09:27 PM 6 hours ago, MACKS said: So when u shut it down does it hold air? I had a lift axle relay valve fail last week, couldn't get air to build passed 65 or so. 1 Quote Link to comment Share on other sites More sharing options...
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