joes mack Posted October 5, 2010 Share Posted October 5, 2010 will a bad air reg let air feed back through? the truck always built air fast but now it leaks off over nite and slowly builds up and goes to 130/150 psi. normaly wouldnt be a prob but its on a fire truck and every sec counts. the truck just started doing this and i believe the high air pres caused the low air switch to start leaking. i changed the switch today... thanks in advance joe Quote Link to comment https://www.bigmacktrucks.com/topic/16010-air-regulatior/ Share on other sites More sharing options...
joes mack Posted October 5, 2010 Author Share Posted October 5, 2010 oh yea i forgot to add the truck has a belt driven air comp and the belts are tight. the truck has a 3208 in it. joe Quote Link to comment https://www.bigmacktrucks.com/topic/16010-air-regulatior/#findComment-64785 Share on other sites More sharing options...
theakerstwo Posted October 5, 2010 Share Posted October 5, 2010 will a bad air reg let air feed back through? the truck always built air fast but now it leaks off over nite and slowly builds up and goes to 130/150 psi. normaly wouldnt be a prob but its on a fire truck and every sec counts. the truck just started doing this and i believe the high air pres caused the low air switch to start leaking. i changed the switch today... thanks in advance joeI dont know what your saying about bleeding back. It ahould not let air bleed anywere but to the unloader valves. It they were leaking by then the air pressure would leak down to maybe 90 psi if the engine was not running.But after that the air is shut off to the unloader. But if this was going on then it could let the pressure to build up higher because the unloader was not unloading. Need more info. In my part of the country only certified mechanics can work on fire trucks. I worked for the dealer many years and never was allowed to work fire trucks. They said first thing i was not slow enough to make it a profitable deal to certifie me.I think i remenber saying thank God.I did work on some ambulances but that was only when they was hard up for help.I also could not work school busses.I could go over and help one of the trainess that was certified. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/16010-air-regulatior/#findComment-64786 Share on other sites More sharing options...
joes mack Posted October 5, 2010 Author Share Posted October 5, 2010 the air will bleed off to 0 on the primary and secondary air systems over nite. but i cant find a leak any where. then it started building really slow and high air pres all at the same time. this has me wondering about the regulatior.. joe Quote Link to comment https://www.bigmacktrucks.com/topic/16010-air-regulatior/#findComment-64787 Share on other sites More sharing options...
Lmackattack Posted October 5, 2010 Share Posted October 5, 2010 sounds like a bad govener if it leting it build over 120 psi. regarding the leakdown. it also may be leaking thru the signal line to/from the govener???? Quote Link to comment https://www.bigmacktrucks.com/topic/16010-air-regulatior/#findComment-64789 Share on other sites More sharing options...
theakerstwo Posted October 5, 2010 Share Posted October 5, 2010 I would replace the air governor first cause they are less than 30 dollars. Then start looking for air leak maybe inside of trans or maybe a check valve is letting air leak back thru to the air compressor and thru the intakee of the compressor. Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/16010-air-regulatior/#findComment-64790 Share on other sites More sharing options...
joes mack Posted October 5, 2010 Author Share Posted October 5, 2010 thanks i will check the gov i was calling it a regulatior for some unknown reason (i must of had a brain fart) the trans is a 5 speed without any air to it i think its a spicer. ill look and see if i can find the check valves and check them for sealing.. joe Quote Link to comment https://www.bigmacktrucks.com/topic/16010-air-regulatior/#findComment-64793 Share on other sites More sharing options...
ducky698 Posted October 5, 2010 Share Posted October 5, 2010 thanks i will check the gov i was calling it a regulatior for some unknown reason (i must of had a brain fart) the trans is a 5 speed without any air to it i think its a spicer. ill look and see if i can find the check valves and check them for sealing.. joeHi, the gove sounds like the best place to start. that would more than likely be your high pressure problem, wheres the safety valve? if thats been blowing off lately due to air it may be leaking? mines in the wet tank, but yours may be differant. you may need to get a bit of garden hose and stick it in your ear and go through all lines and conections to try find the leak.Grant Quote Link to comment https://www.bigmacktrucks.com/topic/16010-air-regulatior/#findComment-64813 Share on other sites More sharing options...
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