Is this an aux air problem?

[Jon Wehrenberg]

Hector is being too modest. Nobody knows the suspension system as well as he does.

I do want to make one thing clear. The leakdown of the suspension system is not the problem, but is a symptom of the problem. When the aux air drops, it in turn causes the suspension to exhaust air as Hector has described.

If you cannot hear the leak here is a tip that may help isolate it.

Your Liberty has a manifold in the lower steer compartment. All of the house systems are supplied aux air from that manifold which may have as many as 6 air lines coming from it. I would suggest you disconnect and plug the air supply to the mainfold to see if the bus holds aux pressure. (you can check pressure with a tire gauge at the valve located on the rear bulkhead of that compartment.

If the aux air holds the leak is in the house side and by removing and plugging the mainfold at each air line you will find which circuit is the leak.

If the aux air pressure drops with the aux air to the manifold plugged, focus on the bus. That could be the door air lock, the belt tensioners, leaks at the solenoids that control the suspension, etc.

My guess is like the rest of us, unless and until you chase them down you probably have numerous small leaks that have occurred over time and were neglected.

[ajducote]

Devin,

Welcome to POG.

If the AUX air leak is large, using a helper, try putting a high volume shop air to the valve in the steer compartment and walk around the coach and listen for the leak. That is how I found a large leak on my tag axle lift chamber. Try to have as little background noise as possible and you should be able to find the general area of the leak.
Good luck

[truk4u]

Devin,

Your aux compressor is behind the two cruiseairs in the front bumper compartment and can only be accessed under the bus by removing an access panel.

Look at my post and you should have an aux pressure gauge and quick disconnect in the steering bay for filling the aux tank. It's easier than running the engine.

http://forum.prevostownersgroup.com/...=aux+air+gauge

Also, if you have a leak that bad, then your engine compressor is running almost continuously while driving and you would hear the air dryer popping off everyone few minutes or worse.

If you need help, feel free to call me at 770-634-7530 since we have the same year bus.

[ajhaig]

Whatever you do... Do NOT crawl under the bus!

[BrianE]

Devin, Welcome to POG. I noticed that both Tom Truk and Hector (Dreamchasers) posted their phone numbers. Both of them, Jon and various other Poggers are VERY knowledgeable.

AJ advised not getting under the bus. If you have mechanical skills and want to fully understand your bus systems you will eventually need to go under. The bus MUST be jacked AND properly supported so that you are absolutely not depending on the air suspension system to keep it elevated. Details of where and how to support the bus are best explained via direct contact with someone who is very familiar with the process. PLEASE avail yourself to the offer of help.

If you have no intention of accomplishing your own maintenance be sure and visit a Prevost maintenance facility and request that a senior mechanic brief you on the under the bus components while it is on the lift. Hand him a flashlight and take notes. Understanding how things work is the best way assist them in trouble shooting future problems and to help you avoid unnecessary repair bills.

The under the bus components are almost identical to those of a modern semi truck. Once safely accessed they are fairly straight forward and can be worked on with some guidance from Prevost maintenance manuals, telephone assistance from Prevost Field Service Representatives, and advice from the membership.

Additionally, be sure to use the Search feature of the forum and click on the bus logo at the top of the forum page and check out the Articles and Information Sharing sections of this site. Many of your questions will have been discussed and answered before.

Good luck, the adventure begins.

[Jon Wehrenberg]

Andre,

I don't want ot hijack Devin's thread, but how did you detect air from the tag axle lifting chamber? Did you suspect it and then lift the tag. It is my belief the tag lift chambers never see air unless the tag lift is engaged.

Just curious.

[ajducote]

Jon,

I could not build air pressure when the tag was lifted. Any time the tag was up, the aux air compressor would not quit running. So I put shop air on the valve in the front compartment and walked around until I heard air. Sprayed soapy water and the tax axle lift chamber made big bubbles. See this link for the cause.
http://forum.prevostownersgroup.com/...ead.php?t=4094