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Thread: Big air suspension leak

  1. #1

    Default Big air suspension leak

    Hey guys,

    I just recently bought a 2000 Ls400 and Iím loving the car so far. It came on aftermarket air suspension which is nice, but it seems to be the only thing causing problems. I have a pretty fast air leak that Iíve narrowed down but I still have some remaining questions that hopefully you experts can help answer. Iím pretty new to air ride, the kit is the Ksport Airtech Deluxe kit with two viair 444c compressors. Iíve found that the check valves from both compressors to the tank are bad and leak pretty fast, the tank loses about 30 psi over night. The tankís pressure relief valve was also leaking when I found the tank filled at 220 psi(yikes) I took it down to 190psi and it seemed like the prv stopped leaking air out, but Iím still skeptical. This leads me to believe the tank pressure sensor is faulty as Iíd be surprised if the tank was supposed to be filled to above 200psi. Not only does the tank lose pressure but the car will air itself out in the matter of about 2 hours. Would the faulty check valves cause the car to air itself out that fast even if thereís still 180 psi in the tank? I would think the tank has to have a lower psi than the bags for the air to start leaking back into the tank and out the compressors. Another detail is that the rear bags empty much faster than the front bags, front are filled to 140 psi and rears to 80 for drive height.

    Sorry for the book of a post, any and all help is greatly appreciated since this is rather urgent!

  2. #2
    Join Date
    Jun 2010
    Location
    windsor, ont
    Posts
    170

    Default

    Have you replaced the pressure relief valve yet?
    About the leaking problem, just go through all the fittings with a spray bottle filled with water and dish soap. Spray the fittings and any that leak will blow bubbles. The rears will both fill and empty quicker than the fronts just because of the weights involved, they will also just be a lower pressure to drive as well. My brothers truck was 50psi in the back and 110 in the front.

  3. #3

    Default

    Quote Originally Posted by scotto View Post
    Have you replaced the pressure relief valve yet?
    About the leaking problem, just go through all the fittings with a spray bottle filled with water and dish soap. Spray the fittings and any that leak will blow bubbles. The rears will both fill and empty quicker than the fronts just because of the weights involved, they will also just be a lower pressure to drive as well. My brothers truck was 50psi in the back and 110 in the front.
    I have 2 SMC check valves and a Schrader valve being shipped so I can replace those because I know they are all leaking. Iíve found the main leak as well, the rear driver side bag is toast. Windex foams up when I spray the bag and I can see that the rubber bag itself looks pretty done. Itís weird because all the other bags look okay and donít leak. No lines or T fittings leak either. So I think it boils down to check valves, tank prv, and one bad bag(can I even purchase a single rear strut? Or do I have to buy 2 rears, or the whole strut kit ). I think the bad valves cause the fronts to lower as tank pressure lowers because itís much slower than the rear. It sucks to have inherited such a poorly maintained air ride system, but itís good to know the problem and hopefully sheíll be back to 100% in no time!

  4. #4
    Join Date
    Jun 2010
    Location
    windsor, ont
    Posts
    170

    Default

    The bag should be replaceable by itself. And its just because they are NPT thread usually, so they are tapered. If the previous owner tightened it too much then a new fitting won't seal up properly.

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