Air Bags

[LaCajun]

While I at this, let me add and ask this question....I have a 1994 Land Yacht. I replaced the air bags approx 4 months ago, but the still leak down while parked. Is this normal, or should they stay aired up a certain amount of time....needless to say I am a newbie to Airstream ownership and air bags...Once the key is turned off, how long should it stay air up.. Thanks for appreciating my limited knowledge.

[porourke]

Are you talking about the front two in the coil springs or rhe back two larger ones that work off the air pump and leveling valve setup?

[gloran]

I was told by the previous owner that this was common, and they all go down in just a day or two. But, I noticed on mine, after its pumped up and the compressor turns off, if I leave the ignition key on,in alittle while the compressor will turn on again and will run a short while and turn off again. Then I can turn the key off, and for some reason the air doesn't leak out. I don't know if this is just my coach, but it would be interesting to see if its suppost to do this. Try it and let me know.

[porourke]

Mine was the same way. I did have an air leak, it was comming form the seals on both the input shafts on both the leveling air valves that adjust the coach rear end heighth. I was lucky they werent that hard to change out. I have the original coach manual with instructions on how to adjust the linkage to the arms to get 10 to 10 1/2 inche heighth. One thing that was confusing is the airvakves have a built in time delay which makes it necessary to adjust them in small inkerments. Now if the rear end is fullly inflated it takes about a week to drop down belo 80 Lbs and start saggin.
Demontrond, the people order from, wanted an arm and a leg for the left and right hand valve. I had already got the part number from AS, Found them online for 76 bucks incluging shipping----

[LaCajun]

Thanks for the response. I will check what you have given me. Hopefully will solve the problem...will let you know.

[Inland RV Center, In]

Originally Posted by LaCajun

Thanks for the response. I will check what you have given me. Hopefully will solve the problem...will let you know.

The cause for the bleed down, is a bad check valve that's in the air supply line, or, a defective air bag.

When the check valve is bad, it allows the air to slowly bleed back thru the compressor.

When the system is functioning correctly, the air cannot bleed off, even over a period of months.

Andy

[LaCajun]

Thanks, I have the diagram in my manual, I will attempt to track it down. How do you determine badness of the valve, or is it best just to replace it. I will check all fittings that I can. Do you have any idea of the cost of the valve and availability.

[Mike Leary]

Originally Posted by LaCajun

How do you determine badness of the valve, or is it best just to replace it.

Do a search, someone a while ago suggested a certain type of spray to check for leaks.

[Inland RV Center, In]

The check valve for the rear air bags, leaks internally.

That allows the air in the bags, to bleed down thru the air compressor.

I don't know of any spray that would find that problem.

Andy

[Inland RV Center, In]

The original air bag check valve was brass colored and about 1/2" in diameter and about 2 inches long.

The replacement is now aluminum colored, and better than one inch in diameter and almost 2 inches long. Certainly a far improvement.

But, they are not cheap.

Andy

[Mike Leary]

Originally Posted by Inland RV Center, In

I don't know of any spray that would find that problem.

Hmm, I just did a search and could not find the post. The spray was for an external leak in the leveling valves.

[Smartstream]

Originally Posted by Mike Leary

Hmm, I just did a search and could not find the post. The spray was for an external leak in the leveling valves.

A little dish soap in water in a spray bottle will work. You can check the check valve by removing it and connecting it back-wards to a compressed air source and using the soapy water. There is a commercial product called Snoop that can be found at industrial supplies.

If you go to any of the air suspension sources all the compressors come with a check valve and they can be purchased separately. You will find them on ebay also. Truck supplies are probably the cheapest source for the leveling valves. Almost all the new highway trucks use them.

Good luck, Dan

[Inland RV Center, In]

Originally Posted by Mike Leary

Hmm, I just did a search and could not find the post. The spray was for an external leak in the leveling valves.

Mike.

The tiny brass air bag check valve, in time, no longer seals completely, which then allows the air to slowly bleed back thru the compressor.

When it does that, of course, the air will deplete in the bags, allowing the back end to drop.

When the motorhome is running, the compressor keeps the air supply up, but in order to do so, it runs and runs and runs.

If someone is having the bleed down issue, and don't change out the check valve, they will soon be buying a compressor as well.

Andy

[porourke]

Check valves block flow in one direction and allow it in the opposite direction. Most are a Ball,spring and cone setup in a tubular sleeve container threaded on both ends. Before I found the leveling valves leaking on my coach this is one of the things we checked. My pump sets just inside the front service compartment area and to the right of the radiator, below it is the 2 or 3 gallon accumulator tank, Commming off the pump is the pressure out line that goes to a Tee fitting. One line going to the Tee comes off of a 12v normally open solenoid that comes on and off with power to the compressor. The other line goes to the check valve. The other side of the check valve goes to the bottom of the accumulator container just below the pump..The reason for the Soleonid is to keep the pump from comming on with Hi pressure on its output and deadheading it.. When the pump comes on and the solenoid comes in it closes the exhaust off the check valve stays closed till the pressure in the lines between the check valve, pump and solenoid gets high enough to over come the spring in the check valve and it opens up sending air to the accumilator. With the system fully aired up, 140# on the dash air guage, we took the line on the side of the check valve loose on the side going to the pump and soleonid, put a short pice of Tygon clear flexable tubing on the end of the check valve and taped it to some of the wireing comming off the pump with the tubing opening pointing streight up. Next filled the clear tube with 3 in 1 oil and waited for bubles to show up and rise in the oil but after an hour decided there was no leakage at that point.

We found the leakage in the leveling valve shaft seals three days later with a mixture of Dawn Liquid Detergent mixed 3 to 1 and sprayed on the valves after we cleaned them up.

[Mike Leary]

Originally Posted by porourke

We found the leakage in the leveling valve shaft seals three days later with a mixture of Dawn Liquid Detergent mixed 3 to 1 and sprayed on the valves after we cleaned them up.

Thanks for a very complete explanation, I knew there was some kind of spray method to check for leaking seals, you found it! Holiday Best.

[masseyfarm]

Originally Posted by porourke

Check valves block flow in one direction and allow it in the opposite direction. Most are a Ball,spring and cone setup in a tubular sleeve container threaded on both ends. Before I found the leveling valves leaking on my coach this is one of the things we checked. My pump sets just inside the front service compartment area and to the right of the radiator, below it is the 2 or 3 gallon accumulator tank, Commming off the pump is the pressure out line that goes to a Tee fitting. One line going to the Tee comes off of a 12v normally open solenoid that comes on and off with power to the compressor. The other line goes to the check valve. The other side of the check valve goes to the bottom of the accumulator container just below the pump..The reason for the Soleonid is to keep the pump from comming on with Hi pressure on its output and deadheading it.. When the pump comes on and the solenoid comes in it closes the exhaust off the check valve stays closed till the pressure in the lines between the check valve, pump and solenoid gets high enough to over come the spring in the check valve and it opens up sending air to the accumilator. With the system fully aired up, 140# on the dash air guage, we took the line on the side of the check valve loose on the side going to the pump and soleonid, put a short pice of Tygon clear flexable tubing on the end of the check valve and taped it to some of the wireing comming off the pump with the tubing opening pointing streight up. Next filled the clear tube with 3 in 1 oil and waited for bubles to show up and rise in the oil but after an hour decided there was no leakage at that point.

Originally Posted by porourke

We found the leakage in the leveling valve shaft seals three days later with a mixture of Dawn Liquid Detergent mixed 3 to 1 and sprayed on the valves after we cleaned them up.

The next used vehicle I buy, I hope it is from a gentleman who does the research and repair like "POROURKE".
It takes time and love of what you are doing to do the RIGHT repair.
It is not difficult, but you have to start the job, determine exactly what the problem is, and with the repair completed, there is the satisfaction that another good job has been well done.
Ownership is only part of the fun. Great satisfaction is gained from exploring every aspect of your unit including repair.
A lot of information on this site and others will generally led you in the right direction.
Always document your repairs so that future investigation will be easier.
Dave

[porourke]

Thanks for the compliment, I have worked at the same company as a Maintence electritan for 46 Years, because of the type production machinery we have I do a lot of hydralic and pnumatic work on the CNC based machines. I will retire in May of mext year, and spend more time with the wife and the Airstream.

TTFN - Pat