88R686st Posted February 11, 2007 Share Posted February 11, 2007 hey guys. today I went to wash my truck 1980 mack. I started let it idle for about 15 minutes before i moved it. and it built air psi no problem so i moved truck left it running steamed it off got in to park it and realised the psi gauge was about 80. moved truck air psi went down but never came back up. so i drained tanks and all that came out was some alchol that i had put in there last week. truck doesnt have an air dryer but we allways drain tanks and put the air line anti freeze in there. also the commpresor is about 2 years old. i dont think the commpressor is coming on i need some help. i was thinking maybe its the governer? any help would be great because they are talking about a big snow storm comming this week and the truck needs to plow. thanx for all your help. Quote 88 R686st 80 R685 93 Ford L8000 02 Ford F550xl 06 Ford F550xlt 06 Ford F350 lariat Link to comment https://www.bigmacktrucks.com/topic/2123-no-air-psi/ Share on other sites More sharing options...
LITrucker Posted February 11, 2007 Share Posted February 11, 2007 My guess would be that you need a d-2 govenor. I had the same prob with a truck at work and it turned out there was a little ice in the line from the gov. to the tank, you may want to blow back through that also.Good luck. Bill Quote Link to comment https://www.bigmacktrucks.com/topic/2123-no-air-psi/#findComment-10375 Share on other sites More sharing options...
88R686st Posted February 11, 2007 Author Share Posted February 11, 2007 awesome. i will try that today. i was heating it up with a torch but no luck. i'll blow the line out with my air hose. and change governer. thanx Quote 88 R686st 80 R685 93 Ford L8000 02 Ford F550xl 06 Ford F550xlt 06 Ford F350 lariat Link to comment https://www.bigmacktrucks.com/topic/2123-no-air-psi/#findComment-10376 Share on other sites More sharing options...
chris88 Posted February 11, 2007 Share Posted February 11, 2007 Your best bet is that air governor, 2 bolts and a couple airlines and you have airpressure again. Quote Link to comment https://www.bigmacktrucks.com/topic/2123-no-air-psi/#findComment-10377 Share on other sites More sharing options...
ThaddeusW Posted February 11, 2007 Share Posted February 11, 2007 It doesn't really sound like a bad governor. The unloader port of the compressor needs pressure to turn the compressor "off". So if you have no air in the system at all, the compressor should start to charge the tanks. Maybe the governor is indeed frozen and the air is trapped in the unloader line holding the unloader valve open preventing the compressor from charging the tanks. Unhook the line between the governor and the compressor and see if the air pressure builds (also see if there was indeed air trapped in the unloader line), or unbolt the governor from the compressor. Be warned that this will not cut the compressor out so you will have to shut the engine down before you over pressurize the system.If you unhook the unloader line and you still aren't getting any pressure also unhook the sender to the tanks and see if air is shooting out which would indicate a clogged line or bad check valve on the tank. if you get no air with both lines unhooked, you have a bad compressor. Quote -Thad What America needs is less bull and more Bulldog! Link to comment https://www.bigmacktrucks.com/topic/2123-no-air-psi/#findComment-10388 Share on other sites More sharing options...
88R686st Posted February 13, 2007 Author Share Posted February 13, 2007 i fixed it yesterday. it was th unloader valves in the compressor. i pulled them out cleaned them up and greased them. she is good as new. thanx for the help. Quote 88 R686st 80 R685 93 Ford L8000 02 Ford F550xl 06 Ford F550xlt 06 Ford F350 lariat Link to comment https://www.bigmacktrucks.com/topic/2123-no-air-psi/#findComment-10429 Share on other sites More sharing options...
LITrucker Posted February 14, 2007 Share Posted February 14, 2007 Sorry about the misinformation, my brain wasn't fully engauged.Ice in the small line:too much pressure. I had ice in the 90 degree elbow going into the tank from the comp line: no pressure.Sorry about that,glad Thad was thinking staight. Bill Quote Link to comment https://www.bigmacktrucks.com/topic/2123-no-air-psi/#findComment-10438 Share on other sites More sharing options...
HeyCharger Posted February 17, 2007 Share Posted February 17, 2007 Be warned that this will not cut the compressor out so you will have to shut the engine down before you over pressurize the system.Thad, I believe my tanks have a pressure relief valve, which should alleviate this problem. I do not know what pressure this is set to.I do agree with you however, that we should be ready to shut the engine down, just in case backups do not work.Regards, Rod. Quote Proud owner of;1961 Mack B61 prime mover.1981 International ACCO 1810C DualCab Fire Truck Link to comment https://www.bigmacktrucks.com/topic/2123-no-air-psi/#findComment-10566 Share on other sites More sharing options...
HK Trucking Posted February 24, 2007 Share Posted February 24, 2007 Most of those pressure relief valves "blow off" at about 150 lbs. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/2123-no-air-psi/#findComment-10744 Share on other sites More sharing options...
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