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Thread: Is this an aux air problem?

  1. #11
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    Jon,

    I could not build air pressure when the tag was lifted. Any time the tag was up, the aux air compressor would not quit running. So I put shop air on the valve in the front compartment and walked around until I heard air. Sprayed soapy water and the tax axle lift chamber made big bubbles. See this link for the cause.
    http://forum.prevostownersgroup.com/...ead.php?t=4094

  2. #12
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    That answers the question. I couldn't figure how you would know the diaphragm was leaking unless you were trying to lift the tag.

  3. #13
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    I remember Tom had air leaking when we had is Coach up on the lift in Oklahoma. Was that a tag leak ?
    Gary & Lise Deinhard, 2003 Elegant Lady Liberty, Dbl slide

  4. #14
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    Gary,

    The leak quit while on the lift and I haven't been able to duplicate it. I have since raised the tag and monitored the aux pressure gauge and no leak down.
    It's still a mystery!

  5. #15
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    I don't know if others have had this issue, but on occasion the pressure relief valve on the engine driven compressor will leak. It seems to occur only when I bring my bus air pressure up via shop air instead of running the engine.

    It makes a sound audible to my ears alone, but will stop after a while. None of my air systems (aux or the two braking systems) appear affected.

    From trying to chase the source of that leak I know it sounded like it was coming from the radiator side of the engine, and it was only through the use of the stethoscope was I able to pin point it because apparently the sound echoes throughout the engine area.

  6. #16
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    Just courious Jon why do you bring up the air in your coach with shop air? Also would your pressure releif valve leak due to too much air form your shop compressor? Rick

  7. #17
    Devin W Guest

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    Thanks everyone for the great info and responses. I have noticed that I can hear what sounds like air leaking/seeping from somewhere in the steer bay, although it seems like it is coming more from the curbside under the stairs. Maybe the fitting for the floor slide needs to be tightened. I didn't have time today to play with it, but if the sun comes out tomorrow then I may brave the cold long enough to drop the front bumper down so I can see if I can access the leak.

    I sprayed all of the other fittings, couplings, etc. near the steer bay door and all seemed to be "air-tight".

    Tom, I don't have an analog gauge like you do in that compartment, but I particularly like the digital gauge that you installed on the dash to monitor the aux pressure. I may do something like that. It could be a good project for when I'm in Houston over X-mas where it will be a bit warmer!

    How does the compressor know what pressure to maintain in the aux system? I didn't see any way to set a pressure or where there may be a sensor on the aux air fitting that monitors that. On the sys 1 and 2 fittings, it's pretty evident where the sensors are for the gauges.

  8. #18
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    Quote Originally Posted by treedoc View Post
    Just courious Jon why do you bring up the air in your coach with shop air? Also would your pressure releif valve leak due to too much air form your shop compressor? Rick
    Rick, If I am working in my garage, rather than run the engine just long enough to build pressure I just air it up from the compressor. I have a big one and it is always up to pressure so it is fast and easy. No I do not over pressurize it. I usually air it up so I can chase a leak or raise or lower it depending on if I am going to work on it from the pit, or if I want to drop it down to clean it. (You need aux air to work the Norgren valves to make the bus go up or down)

    Short time running of the engine is not the best thing you can do for your coach. If you are going to run it, it is always best to run it long enough for the engine to come up to temperature and to get hot enough to evaporate any condensation that may collect.

  9. #19
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    Quote Originally Posted by Devin W View Post
    Thanks everyone for the great info and responses. I have noticed that I can hear what sounds like air leaking/seeping from somewhere in the steer bay, although it seems like it is coming more from the curbside under the stairs. Maybe the fitting for the floor slide needs to be tightened. I didn't have time today to play with it, but if the sun comes out tomorrow then I may brave the cold long enough to drop the front bumper down so I can see if I can access the leak.

    I sprayed all of the other fittings, couplings, etc. near the steer bay door and all seemed to be "air-tight".

    Tom, I don't have an analog gauge like you do in that compartment, but I particularly like the digital gauge that you installed on the dash to monitor the aux pressure. I may do something like that. It could be a good project for when I'm in Houston over X-mas where it will be a bit warmer!

    How does the compressor know what pressure to maintain in the aux system? I didn't see any way to set a pressure or where there may be a sensor on the aux air fitting that monitors that. On the sys 1 and 2 fittings, it's pretty evident where the sensors are for the gauges.
    Devin,

    The topic of air leaks, how to find them, where they might be, the aux compressor, how pressures are regulated, etc. is difficult even if all of us have the same conversion. The complexity of the issue goes up exponentially as we are faced with upgrades made by the converter (your Liberty and mine may not have the same compressor for example), changes made by owners over the years and differences between other conversions and ours.

    But we might be able to generalize. Often our aux air compressors on Liberty coaches use what looks like a well pump switch, mounted on the rear wall of the steer compartment bulkhead. It is adjustable and the range may be anywhere from 40 on to 80 off to 80 on to 100 off. Most I have heard of use the 100 PSI upper limit.

    Finding air leaks is more art than science. Amongst this group we use our ears, soapy water, stethoscopes and ultrasonic leak detectors. None of the previous work for all leaks, and each method has its strengths and weaknesses. If you turn your coach over to someone and ask them to make your aux system leak free for example, it is likely you have just paid for someone's kid's college education. I'm only half kidding.

    If you can hear the leak, you will recognize it is hard to pin point its location because of the ability for a leak over here to sound like it is coming from over there. The next step is to spend $5.00 at Sears on a stethoscope which when pointed at the leak amplifies its sound making it easier to locate.

    There is not enough space or time to provide much more on this but as you play around chasing leaks post your findings and the inmates of this asylum we call POG can offer advice and tips.

    BTW, If you think the floor slide is a culprit locate the air line feeding the solenoid valves that operate the slide and cap the air supply to them. The air leak should go away. The cylinder is serviceable, but before fretting over that the best bet is to prove that is the problem, or at least one of the problems.

  10. #20
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    Devin,

    Jon already mentioned the aux pressure and it being adjustable. If you think the leak is the floor slide, just put it in the out position and with the door open, you can get to the air cylinder and squirt it with some soapy water. It sounds to me like you have more going on than the floor slide or else your aux compressor has a serious leak. Keep looking, you will narrow down the leaks, but you'll never be leak free!

    Here's a few general places to look for aux leaks with your vintage:

    Steering bay
    Floor slide
    Generator bellows & regulator
    Grey water by-pass cylinder
    Waste tank dump cylinder
    Air horns
    Toilet - if it's air like mine
    Aux compressor & fittings

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