Air Governor

Discussion in 'Experienced Truckers' Advice' started by stinerspecialtransport, Aug 25, 2011.

  1. stinerspecialtransport

    stinerspecialtransport Bobtail Member

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    Aug 18, 2011
    Midland, TX
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    Yesterday I parked my tractor, left it idling, and went in to sit down and eat. When I returned I noticed a problem with the air governor. This is what it's doing:

    It builds pressure to 120 psi and kicks out, but it leaks off air until it reaches 110 psi. Once it reaches 110 psi, the compressor kicks in and builds up to 120 psi again, then leaks down to 110 psi, and the compressor kicks in and builds back up to 120 psi. It's a never ending cycle. I got down near the governor (I guess that's what it is....drivers side behind the steer tire (on my 98 pete 379 EXHD) , where you can hear the regulator pop. I cleaned it up, soaked it in WD40 to loosen all the grease and grime. There is a piece at the rear, seems to be possibly plastic, and that's where the 10 psi is leaking off at.

    I need help trying to get this fixed. It's driveable, but it's definitely annoying at night while im trying to get some sleep.

    Any input would be greatly appreciated.

    Thanks,
    Toby
     
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  3. brian997

    brian997 Bobtail Member

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    Jul 20, 2011
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    Just replace it.. they cost like $8

    Oh and if you are looking for info on how to replace it, its pretty easy, just two bolts (and they come with the govener when you buy a new one)
     
    Last edited: Aug 25, 2011
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  4. stinerspecialtransport

    stinerspecialtransport Bobtail Member

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    Aug 18, 2011
    Midland, TX
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    Is that the capsule shaped piece under the hood near the compressor?

    Thanks,
    Toby
     
  5. Mr. PlumCrazy

    Mr. PlumCrazy Road Train Member

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    This is it
     

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  6. stinerspecialtransport

    stinerspecialtransport Bobtail Member

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    Aug 18, 2011
    Midland, TX
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    Yes, the black piece with the fins is where it's leaking. So, this part is only $8? Also, I have another question. How and where do I adjust governor cut in (90 psi) and governor cut out (120 psi) settings?

    Thanks to all,
    Toby
     
  7. grizzly

    grizzly Medium Load Member

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    Layton, Ut
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    It might be a $15 part depending on where you buy it. I carry an extra with me. There are adjustment screws on the governor. Just watch your air gauge and adjust the screws accordingly to how you want your air to spit off.
     
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  8. Rollover the Original

    Rollover the Original Road Train Member

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    Springfield,MO
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    Unscrew the part with the black fins. Look on the black part (the cap) with the fins. Is there an "O" ring seal? Is it cracked or broken? OR a groove where there should be one? If so take the cap to a dealer. Any dealer not just Pete, and get the ring and put it back together and see if that didn't stop the leak. If you are at a truck stop with a shop see if they have one. Besure to lube the seal just like on an oil filter so it will slide as it's tightened and won't break it. Inside there is a screw adjustment with a nut lock. It's been a long time since I adjusted the regulator but it's simple. Loosen the locking nut just like on the valves in an engine if you have ever done any tinkering with engines.

    Screw it in or down just a little and then get in the truck and pump the brakes until the compressor kicks on. You said it comes on at 110 pounds which is a little early. 90-100 pounds was where I kept mine at. That's above where the emergency brakes come on and not so low that the AP doesn't work hard to fill the tanks back to 120. You might have to try different settings but keep track of where the pressure comes on at and if it goes in the wrong direction of where you want it to come on at go the other way with the screw. Just be sure that you lock it with the nut by holding the screw with the screw driver while you tighten the nut with your wrench.


    The water separator is that part mounted somewhere on the frame that the air lines go to and separates the water out of the system. You know that part that the air comes out of when the system hits 120 pounds and usually the drain is pointing down and can scare the begeezes out of you. Once it realeases at 120 or whatever pounds it should not keep leaking. The valve might be going bad. This is a shop repair.

    Air leaks are one of the biggest problems in trucking. There are many fittings in the system. DOT loves air leaks as it can be what will get you an OOS until repaired.

    Get the truck up to pressure and shut it off and go on a search! Hopefully you are in a nice and quiet area with no idling trucks close by. Find everyone of those leaks either by listening or by spraying a soapy water mixture on the fittings and look for bubbles. Also look at the air lines for rubbing and wear marks and even drying out or dry rot cracking.

    If it is a fitting you can try to tighten that first. If that doesn't work then remove the fitting and use any Teflon thread tape and wrap the male end and put it back together. Teflon tape will work in all applications where air, fuel or water leaks from a fitting. Have a roll in the tool box.

    Air chambers are another problem and unless you have a shop at the house a mechanic should do any work on it. Messing around with an air chamber can kill you if it comes apart and you are in front of it!

    If that compressor keeps kicking on that much then you have a pretty leaky system. It is extremely irritating when someone parks next to you and every minute or so the relief goes off. makes you want to cut the power to it or knock on the door! Help your mechanic by looking for the leaks and write them down so they can fix them all.

    Here is one reason to have a creeper in the side box. I had a collapsible one for years until someone liked it better than I did along with a lot of my stuff in the cab and took what they wanted. I couldn't find one after mine went away!
     
  9. puncher

    puncher Medium Load Member

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    Roll over the original is right on, and all this can drive you crazy. I've had drier cartridges do the things you describe. You can unscrew the incoming and outgoing lines going in and out of the drier and use a male double male nipple to bypass the drier, it will not spew after this, but if it will build to whatever your governor is set at then you have found your problem.
     
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  10. stinerspecialtransport

    stinerspecialtransport Bobtail Member

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    Aug 18, 2011
    Midland, TX
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    Roll Over,

    Thanks alot for being so detailed in your response. It's a huge help to a rookie mechanic and o/o. lol.

    Thanks to everyone else for your input.

    I'm a new member to the forum and it's already saved me hundreds of bucks in labor costs.

    Thank you,
    Toby
     
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  11. brian997

    brian997 Bobtail Member

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    Jul 20, 2011
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    Did you get it fixed alright? Or did you get a new one installed?
     
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