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wildtoad · 03-05-2004, 11:49 AM

This may be similar to the Dumping Air thread, but then again may not. I took my 1994 33' LY in for some service for leaks and the rear air bags. Seems there was an air leak with the result being the coach would rest on the rear wheels. When I cranked the engine the air pump would come on and raise the coach off the tires and all was well with the world, but I felt it needed looking into.

The dealer checked it out and had to order some parts and I got it back today. They said the PO had bypassed the auto leveling feature but it was now back up to spec. and that I will notice the guage fluctuating as air is added and released from the bags as the systems attempts to keep the coach level. Well, now the pressure gauge does indeed fluctuate but the pump never turns off. I drove it from the dealer to home (20 miles all interstate) and the guage would go from say 70 lbs to 20 lbs and everywhere in between.

So is this the way it's supposed to work ? Could the leveling switches be to sensitive and releasing air too often ? I have to think that running the air pump all the time will be bad for it.

Thanks for all thoughts.

ALANSD · 03-05-2004, 11:53 AM

just a guess for me, but the line to the gauge may have a leak?
It would seem that load adjustments by the compressor woul not happen that much except under some severely shifting weight loads.

wildtoad · 03-05-2004, 01:15 PM

Thanks, I'll take a look. BTW I've looked in the manual and it references and shows a tank that you need to drain the water out of every now and then. The manual indicates it under the coach, but the only tank I can find that sort of fits the description (about the size of a small coffee can) is a very small one under the hood under the pump. ?

swebster · 03-05-2004, 01:17 PM

wildtoad,
My gauge fluctuates only slightly (+/- 10 psi) while on the road. Obvious stuff..over a bump, etc.

Try tacking a manual reading with a tire gauge off the tank valve itself. Then compare that to your dash gauge reading. On mine the high limit is set to 105 psi and it'll cutout then. Honestly this is a little too harsh for me because I'm usually traveling fairly empty so I have a switch on the dash which allows me to turn off the pump manually when it gets to 90/95 psi.

Once it's up to pressure let it sit for a while and take readings every few hours. If it drops a lot of pressure over say a six hour period then you could have a leak.

I fixed my "always on" issue by replacing the check valve from the tank....it was leaking and therefore the pump would just run, trying to keep up with it.

swebster · 03-05-2004, 01:19 PM

wildtoad,
The tank should be mounted in the rear of the coach between the frame rails. Mine is in between the tag axles. Its a good sized tank (about 2x longer and a little thinner than a propane tank from a gas grill) with air lines going into one end and coming out the other so you'll know when you see it.

wildtoad · 03-05-2004, 02:39 PM

Stephen,

Thanks for both replies. My 33' does not have a tag axle. And after another long search, no tank under the coach.

But I did go and find the replacement part the dealer put in. It is attached to the frame and has one tube coming from the front of the unit, one tube going to the air bags, one clear plastic tube that looks like a drain tube(?) and then there is a metal bar which is attached to this device and to the crossmember that supports the air bags.

Am I correct in that: everytime the rear of the coach bounces thus compressing the bar this device will add air to the bags (raising the coach) and then everytime the coach returns to normal (bar decompresses), the device will release air from the bags? This seems like a grand plan assuming the pump and tank produce way more air than the process releases.

swebster · 03-05-2004, 03:02 PM

You are on the right path...there is a built in delay in the air leveling valves to prevent unecessary movement of air when going over a bump or rounding a turn. The basic idea is that as a wheel gets low (low air, turn, etc.) the rod pushes on the valve which puts air into that bag....and when the ride height comes back up it turns off the valve. Same thing the other way. Not sure if your setup is the same since its much newer than my 86 but this it's a pretty simple valve system back there. You should have an accumulator tank somewhere as the compressor can't put out enough air on its own to keep things inflated on demand.

wildtoad · 03-05-2004, 03:34 PM

Unfortunately I think the small tank up front is the accum. tank. I'm not sure if what I have is what is documented in the book. But the feed from the leveling device goes to one bag which is tied into the other bag, so any air added / released is from both bags at the same time.

ALANSD · 03-05-2004, 03:56 PM

On mine you can't check the pressure at the tank, because the check valve keeps the pressure up in the bags, and is between the bags and tank. If the tank you found is it, it should have some sort of schrader (tire) valve or drain line on it.

wildtoad · 03-05-2004, 04:33 PM

It does have a valve on the bottom of it in the shape of a bow tie not a tire fill type valve. I turned it and a few drops of water came out. No place to check the pressure though.

swebster · 03-05-2004, 05:39 PM

That sounds like a petcock (drain valve). Did air come out too?

jim8860 · 03-05-2004, 10:17 PM

Quote:

Well, now the pressure gauge does indeed fluctuate but the pump never turns off. I drove it from the dealer to home (20 miles all interstate) and the gauge would go from say 70 lbs to 20 lbs and everywhere in between.

That is no good.
I have a 95 MH and I had some of the same problems that you are having. First Airstream told me that hey never installed a single axle air ride system before. I said that funny I have a seen a few of them at the dealer. Anyway this is what I found out. I found who made a the air ride system for Airstream and I talk to a guy over at www.trailer1.com and knew all about it. I have the bag number in the coach if you need it. At the time the only bag that was a direct bolt in were in a backorder for a long time so I found a different number that works just as well and is a very common number. The pump should only cycle on a few times over the road. If the road if smooth it may never cycle. On mine the air tank is under the pump by the motor battery. My tank crack on me and caused the pump to run and run not good, the pump will burn out. The system should run at 80-90 psi and should turn off at 100 psi "ish" and turn on about 70 psi "ish". The air should not leak out for a very long time like 3-5 days. My camper what always on the ground after a minutes of parking, not good. The air also dumps when you put up the jacks. The ride height "should be" 10.5 inches from the top of the bag and to the bottom of the piston/stand it sits on. I tried that but the MH was a low rider. My MH sits @ 12 inches and has a bit of a rake to it. Check the little tank under the compressor for leaks, use Windex it work nice for bubbles. Turn the key on and spray all the fitting and tank and even the compressor they should be no leaks at all. The leveling valve will regulate the height of the MH and should not leak until the bags get to full of air or the MH leans form side to side. Any question ask me. Good luck its an easy system and it easy to fix.

wildtoad · 03-06-2004, 05:14 AM

Steven, no air came but the unit is not level and there was only about 30 psi on the guage when I shut it off. I'll check it again.

Jim, sounds like we have similar setups and yes it looks like a fairly simple system. I may get to look at more of this on Sunday.

Thanks all for the replies.

ALANSD · 03-06-2004, 06:53 AM

" First Airstream told me that hey never installed a single axle air ride system before. I said that funny I have a seen a few of them at the dealer."
And all the 270 and 280 models have that as well. Maybe they mean they haven't installed one lately! My air ride sounds like a siiliar set up ,a lthough the tank, and "grey box" which is part of the automatic levelling; are located in the rear compartment opposite my shore power set up. I am using a manual valve to fill as my compressor died and has not yet been replaced.

wildtoad · 03-06-2004, 01:57 PM

So today I go out with my handy dandy spray bottle of windex to check for leaks at the tank, pump, etc. I turn on the key, the pump starts and pressure starts to build. I spray the fittings at the tank, pump, bags and no air appears to be leaking. I turn the petcock valve and low and behold air does come out this time, so this is the accum. tank. The pump pumps until it reaches 130 psi and shuts off and it appears to hold so I surmise there is no leak, or at least no significant one.

So now I go to the left side rear tire which is near the area where the leveling device is mounted and start rocking the boat side to side. With each "rock" I hear air escaping from under the RV indicating the leveling device is doing what it supposed to do. After several times, I hear the pump start up again to replenish the accum. tank. So I think things are working as designed but perhaps the tank/pump is too small for this type of application.

Jim, you say it should pump range should be between 70 and 105 psi. Is there an adjustment for this on the pump or is it preset at the factory ?

Does anyone know if there is an adjustment as to how much air is released from the bags or a way to adjust when the air is released so that only significant rocking causes the gates to open?

thenewkid64 · 03-06-2004, 02:32 PM

Max Psi is based on the coach. On the older classics it was a lower max. There should be a gray box Teed into the line right at the compressor this box has the pressure switch in it. If Yo want to adjust the cut off pressure you remove the cover and there is an adjuster in there. I do not know of a way to set the leveling valves to not purge air in a rocking situation. One thing to check is the condition of your shocks. The rig could just me moving too far and causing the valves to activate.

Based on your symptoms I would be willing to be there is a check valve in the pump and it is failing. This valve allows the pressure to leak out of the system and the pump has to restart to re-pressurize the system. A check valve can be added between the pump and the T fitting to stop this. The additional check valve will also prolong the pump life because the pump will be starting with little or no back pressure at startup.