Jason49b Posted May 21, 2019 Share Posted May 21, 2019 Ok truck has a compressor that is 1 month old, new governor installed one week ago and new filter in the air dryer. Truck air pressure is at 120 psi at idle, start driving it pressures up to 150 and the dryer never pops off can’t seem to figure out why it’s going to 150, we’ve done blew two air hoses everyone I talked to is lost as we are if any one can help me out it would be much appreciated Quote Link to comment https://www.bigmacktrucks.com/topic/57302-jason/ Share on other sites More sharing options...
Rob Posted May 21, 2019 Share Posted May 21, 2019 Compressor make and type? The unloaders are not functioning correctly is the root problem and it's constantly making air pressure when it should not be. If you are blowing hoses your system relief valve in the wet tank is not functioning as it should release pressure over 150psi. 1 Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/57302-jason/#findComment-423253 Share on other sites More sharing options...
Freightrain Posted May 21, 2019 Share Posted May 21, 2019 Can you hook up the unloader to shop air. While compressor is running, apply air to see if it quits pumping. If it doesn't, then the valve in the head is hanging up? Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/57302-jason/#findComment-423298 Share on other sites More sharing options...
JoeH Posted May 29, 2019 Share Posted May 29, 2019 I had a tractor that did this, it blew the line that runs from compressor to the governor. I've had new governor's bad out of the box. Don't rule it out. Quote Link to comment https://www.bigmacktrucks.com/topic/57302-jason/#findComment-423924 Share on other sites More sharing options...
Mack Technician Posted June 23, 2019 Share Posted June 23, 2019 (edited) On 5/29/2019 at 5:40 PM, JoeH said: I had a tractor that did this, it blew the line that runs from compressor to the governor. I've had new governor's bad out of the box. Don't rule it out. Had a bad air governor right out of the box last fall. Makes you second guess yourself. Edited June 23, 2019 by Mack Technician N Quote Link to comment https://www.bigmacktrucks.com/topic/57302-jason/#findComment-426007 Share on other sites More sharing options...
Rob Posted June 23, 2019 Share Posted June 23, 2019 Yup, don't trust those Bendix D2 knockoff's. Seen several either not make initial testing, or fail shortly afterward. Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/57302-jason/#findComment-426009 Share on other sites More sharing options...
theakerstwo Posted June 23, 2019 Share Posted June 23, 2019 before you do any more changing block the signal line to the drier and see if it cures the problem.If the purge vale in the drier is leaking the undloader pressure then the unloader in the compressor will not unload.This is common on a AD4 or 9.Just use vice grips to block the signal line. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/57302-jason/#findComment-426021 Share on other sites More sharing options...
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