Air bags leaking down on one side of bus

goutoe · February 12, 2018, 11:43:41 AM

I have a leak somewhere on the passenger side air bag system, I have checked the air bags and level valves no leaks found, I did have a leak on the engine shut off valve, replaced it, and it still leaks down, The drivers side will stay aired up for months, the passenger side will go down overnight! any Ideas?? >>>> John.

gumpy · February 12, 2018, 12:06:55 PM

While I'm not familiar with your particular breed of bus, it's not uncommon. it could be a leak in the air bag seals or bags themselves. If you have air beams, it could be a leak there. It could be the leveling valves leaking out or back through the valve. If you can't find it with soapy water, you could try putting a shutoff valve in the lies temporarily to isolate it. Might have to move the valve a few times to narrow it down. Otherwise, for a leak that slow, it may not be a problem.

richard5933 · February 12, 2018, 12:07:18 PM

Had the same thing on our last bus. Nothing magical about it - just follow every line and spray with soap water looking for the leak. Got to be one somewhere, but they are often difficult to see. Have you tried using a mechanic's stethoscope to listen for the air escaping?

If you're going down overnight the leak should not be totally impossible to find. Mine took about 4-5 days to drop and I ended up taking it to the shop so they could put it in the air and do a more thorough search. Ended up being a leak at a fitting in the copper line. I've got one on our current bus that I'll start looking for once the weather warms a bit more.

Good luck.

goutoe · February 12, 2018, 01:15:26 PM

I suspected the level valve from the start but I soaped it down and found nothing, unless its bleeding through the valve and back through the compressor? is there any check valves that could fail? I will try listening with a stethoscope when it warms up a little! this cold weather really complicates things!! >>>> John.

richard5933 · February 12, 2018, 01:35:32 PM

Quote from: goutoe on February 12, 2018, 01:15:26 PM
I suspected the level valve from the start but I soaped it down and found nothing, unless its bleeding through the valve and back through the compressor? is there any check valves that could fail? I will try listening with a stethoscope when it warms up a little! this cold weather really complicates things!! >>>> John.

Not sure about the leveling valve on your bus specifically, but in theory that is possible. There is a check valve of sorts inside the leveling valve according to what I've been told. I'm sure that others here have more experience and can address that more fully.

Templar52 · February 12, 2018, 02:12:48 PM

Inside each leveling valve you have a valve. The same kind of valve you have in your bicycle tire.
If you check everyting with soapy water and noting appear.....remoove this valve and clean or replace it. The valve is situated on the entry side of the leveling valve. If this tiny valve is defect,the air from airbags will return to the suspension reservoir.

goutoe · February 13, 2018, 06:32:11 AM

Thanks guys, I will go back to the leveler valve and start there.>>>> John.

chessie4905 · February 13, 2018, 08:33:25 AM

I diagnosed mine a few years ago with an adapter to isolate the air bag before I fooled with leveling valve and lines. I used a Schrader valve to add air to bag with adapter to line going to bag. Pumped it up to about 80 pounds and left it set overnight. I would recommend a longer line to connect to the airbag. You don't want to be close of one decides to blow. It will, at the minimum, ring your bell big time. It was flat next day. Be sure to soap connections to air bag and Schrader valve to avoid a false positive.

goutoe · February 13, 2018, 12:21:39 PM

Chessie, I may try airing up one bag at a time, I will take your advice and use a long hose lol. I wouldn't want to be close if one blew!!Thanks.>>>> John.

gumpy · February 13, 2018, 03:06:42 PM

Quote from: goutoe on February 13, 2018, 12:21:39 PM
Chessie, I may try airing up one bag at a time, I will take your advice and use a long hose lol. I wouldn't want to be close if one blew!!Thanks.>>>> John.

Unless your air bags have been plated, you can't easily air them up one at a time. They are in pairs, connected to the air beams. You fill the air beams and both bags inflate.

chessie4905 · February 13, 2018, 04:03:02 PM

You sure about this Gumpy? It is an AM General from his info.

gumpy · February 13, 2018, 04:08:29 PM

Quote from: chessie4905 on February 13, 2018, 04:03:02 PM
You sure about this Gumpy? It is an AM General from his info.

Oh, yeah. Forgot what we were dealing with here. Was thinking it was an MCI. Different thread, I guess.

Well, I retract what I said previously.

chessie4905 · February 13, 2018, 04:24:27 PM

You sure about this Gumpy? It is an AM General from his info.

chessie4905 · February 13, 2018, 04:25:28 PM

Sorry about that twice, didn't know that was possible.

Branderson · February 14, 2018, 11:19:50 AM

Can someone help me understand? When the OP says one side can stay aired for months, that confuses me. I have a MCI and as soon as I turn it off, I start to lose air. I think after about 5hrs or so, it's completely down. As soon as I park and shut it off, I have to put blocks under for my leveling. Do other busses stay aired differently?

Maybe his bus stays leveled by air?