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Old 07-22-2013, 12:35 AM   #1
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Wetaskiwin , Alberta
Join Date: Nov 2012
Posts: 68
The tale of my 1989 345LE air suspension system

When I bought my Airstream I faced a 2400 mile 3 day journey through 8 states and 3 provinces to get it home. I had no idea it even had an air suspension system. My first inkling was when I went back to find out what the racket was that I could hear constantly as I drove. Eventually through using the manual and numerous trips inside and outside the vehicle, I located the compressor, beside the bed, in a corner closet at floor level, behind a wooden boxlike partition. It just kept on buzzing away all the time the ignition was on. I then read about the air pressure gauge on the dash, which showed NUTHN. Then I found the airbags, and they were apparently flat, but there was a tube leading from a tire valve near the waste water tanks, to an air tank. I stopped at a gas station and spent 5 minutes filling the tank, and had the satisfaction of seeing the air bags rise off their cones. I drove off... same constant compressor noise, the gauge on the dash showed 90 psi, then 70, then 50, then 30, so I pulled in at a gas station. Looking at the air bags, they still looked good, but the tank was empty, so I refilled it. Off again, same noise, pressure dropping. After repeating this process a couple of times, I realised I didn't need to. Obviously the compressor was doing nothing, so I disconnected the power lead to it, and every time I stopped to apply for a mortgage to fill the gas tank, I'd check the air bags. I only filled the system one
more time in the whole trip.

Life is full of travails, whatever they may be, and some serious stuff came along in the next 18 months that pushed the 345 to the bottom of the priority list, until a month ago I started her up and drove her out of storage. She had no brakes, and flat air bags. The brakes seem OK now, and I've discussed those elsewhere, but I've been chewing away at the air suspension system on and off for a couple weeks now. First off, someone did a lovely job of plumbing and wiring the system: it
looks very pretty, as can be seen form the attached picture, but whoever did it either could not read or had no access to the AS manual, which is actually very clear on this system.

Before I could start on the system, I had to replace the air tank, which had decided to develop a pinhole leak. I found a suitable tank, labelled the connections, and plumbed it in. In doing so I found the check valve, and ascertained that it was indeed on the correct tube coming from the compressor. I took this valve apart, as it is obviously made to be taken apart, cleaned up, and reinstalled, so I did so. There generally wouldn't seem to be a reason to buy a new one of these, if the old one isn't heavily corroded, since you can get them back to new condition in about 3 minutes, so that's recommendation number 1. Plumbing the air tank finished, I filled the system through the tire valve. The gauge on the dash went up to 110 psi (and if you have worked on these systems, that's a red flag, but I didn't know it then), and then leaked down over the next hour or so, although the air bags stayed up.

I was Soooo depressed by the leaking: I'd used white teflon tape on all the joints, upside down for about 2 hours, spitting grit out from between my teeth, getting rust and road salt in my eyes, and the system still leaked. I filled a spray bottle with soap solution, refilled the air tank, went under the AS and sprayed, and it was like one of those bubble making machines from the disco era, without the Bon Jovi music. ALL my bigger joints leaked, and the tank I bought had two 3/4" and two 1/2" inlets that I'd had to reduce down to 1/4". I then had a brainwave, went and got my yellow teflon tape I'd used for sealing joints on my bulk fuel tank, took all the joints apart and
resealed them using the yellow tape. Perfection, or nearasdammit. It took 8 days for the air tank to leak down from 110 psi to 30 psi. So here's recommendation number 2: only use the white tape on
3/8" or smaller joints, and for all the bigger ones use the yellow tape: easy to use, doesn't shred, and using it you can rock your joint right up to the last thread. At last I'd made some progress, back to square one, that is.

So on to the system: It has to be the most awkward and painful position I have ever had to adopt trying to get in the damn closet beside the bed. Up on one elbow, trying to make the left elbow
bend the wrong way, screwing and uscrewing using my left hand little finger and ring finger because they were the only ones that would reach. But somehow I did it, although I am still covered in bruises over both arms and shoulders and my left ribs. I took out the compressor to have a look at it. Looked pretty near new, but obviously had been partially dismantled. I took the "head" off, and sandwiched between it and the body are 2 gasket-like sheets of metal that are actually the
valves of the compressor. I looked and looked at those valves, and realised that they had been inserted so that the compressor was sucking through its outlet (against the check valve) and blowing through its inlet!! Hence the constant compressor noise and no air. Two minutes later it was back together correctly assembled.

Next I started to try and figure out the system, that apart from the compressor didn't seem to be OEM. In the picture you'll see that A is a pressure switch, supposed to switch on when pressure drops to 80 psi, and off again at about 110 psi. At B is a solenoid that is triggered when the compressor stops, to drain pressure from the compressor so it isn't going to have to start against pressure next time. At C is the pressure sender that receives pressure data from the air bags and
relays the pressure electrically to the dashboard gauge. Finally at D is the relay that is triggered by the pressure switch A to feed 12v to the compressor, so starting it running. All this looked good, but I took the pressure switch off, and couldn't get it to switch off at 110 psi, although I'm not sure I reached that pressure with my compressor, but decided to replace the switch anyway. It was tough to find one that was the correct 80/110psi rating, but eventually I found a new, very small switch at Acklands Grainger, the Canadian version of Grainger, and I've attached a picture. Also pretty cheap. I remade the electrical connections to it, and turned my attention to the air tubes.

I decided I'd better not take anything for granted, so I traced each one. This was made more complicated because all tubes had apparently been replaced, but all the old ones are still around,
taped up uinder the vehicle. Anyway, to make a long story no longer, I found the following: The tube E that should have come from the air tank to the pressure switch A actually was connected to.... NUTHN. I couldn't even locate the other end of it under the coach, but there was no pressure going to the pressure switch. The tube F that went to the pressure sender C and should have come from the air bags actually had full tank pressure, which was why my dashboard gauge would
leak down when the air bags stayed up. In the picture you'll see a blanked-off tube H on the right, and THAT.... came from the air bags! (as I found out when I unscrewed the blanking plug and a big HUFFFF of air came out and the coach dropped 6 inches). So, I connected hose H to the pressure sender C, I took hose F and connected it to the pressure switch A. I then started the engine, the compressor started, the pressure on the dashboard gauge rose steadily to about 70 psi
and held, the compressor rattled away for another 5 minutes or so, then a big sigh from the solenoid B and the compressor quit. Tire gauge measured the tank pressure at exactly 110 psi. Hey presto! It all works!

There had been one more surprise though, although I'm not prepared to deal with it yet: I found that there was only one wheel levelling valve, on the driver side.... no sign of the other. Whoever rebuilt the system has both air bags filling off the one valve. It seems to work well and the coach handles very well, but I guess when I recover my desire to slide around on my back under the coach spitting grit again, I'll restore that part of the system. If anyone is still reading this, I congratulate you on your stamina!
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Old 07-22-2013, 01:21 AM   #2
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1936 20' Clipper
1947 22' Liner
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1989 37' Airstream 370
marshfield , Massachusetts
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Great story line. Fantastic tale. Loved the ending. Pulitzer worthy. Now for my next read; 'War and Peace".

All kidding aside, that was really informative. Thanks.
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Old 07-22-2013, 02:05 AM   #3
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1974 Argosy 20
2014 20' Flying Cloud
Kooskia , Idaho
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On the one vs two leveling valves: My 83' 310 only had one valve as original equipment, while my friends '81 had two valves. So, yours may not have had two to begin with.

And I enjoyed your story, I think I got my 310 much cheaper than I should have because no one could figure out the air suspension system. So, I had a similar saga to go through to get mine to work well. Once I sorted it all out, it would go for sometimes a thousand miles between times the compressor ran, and if sitting unused, would never leak down at all. But when I got it......well, like you, I had a lot to learn.
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Old 07-23-2013, 08:26 AM   #4
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Wetaskiwin , Alberta
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Quote:
Originally Posted by idroba View Post
On the one vs two leveling valves: My 83' 310 only had one valve as original equipment, while my friends '81 had two valves. So, yours may not have had two to begin with.

And I enjoyed your story, I think I got my 310 much cheaper than I should have because no one could figure out the air suspension system. So, I had a similar saga to go through to get mine to work well. Once I sorted it all out, it would go for sometimes a thousand miles between times the compressor ran, and if sitting unused, would never leak down at all. But when I got it......well, like you, I had a lot to learn.
The reason I think it had two valves is that the old tubes to the valve on the passenger side are still there, tied up to the frame. But It's very interesting that yours only had one valve.... maybe if it works that way I should leave it as it is.

You got yours completely leak free!? Guess I'd better get back under there with the soap spray again!
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Old 07-23-2013, 10:05 AM   #5
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1974 Argosy 20
2014 20' Flying Cloud
Kooskia , Idaho
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Quote:
Originally Posted by Penmaenmawr View Post
The reason I think it had two valves is that the old tubes to the valve on the passenger side are still there, tied up to the frame. But It's very interesting that yours only had one valve.... maybe if it works that way I should leave it as it is.

You got yours completely leak free!? Guess I'd better get back under there with the soap spray again!
Yep, it could sit all winter and in the spring when started, the compressor would not even come on. Yes, Virginia, there is a Santa.

Now, I had a GMC motorhome with air suspension, and that was a different story.
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