Big time air leak

[Pete]

Started the bus this morning, and the front would not come up. I switched the level low to the front, raised the front, and as soon as I stopped the engine, the front went back down quickly. I repeated the process, stopped the engine, exited the coach and could hear a massive amount of air escaping from the right front tire area.
The air escapes so quickly that I cannot get the new jack stands underneath safely.
The coach was just used last week, then parked in my shop. All was well during the last use.
Air bag rupture? Valve stuck? Bad relay? Your thoughts please.
Thanks, Pete

[jj628]

I'm having the same problem just not quite as quick. Just started. jjf

[Jon Wehrenberg]

Pete,

The right front tire area has no valves. It sounds like the problem is a fitting or air bag leak on that side.

You cannot drive the coach that way so the best advice I can give for now is to run the coach on high idle and if necessary have EJ command the coach to raise in the front. If it goes full travel and stays that way you may be able to slide one of the stands under the support point. At the least try to get the shorter one under the coach.

There is a hazard associated with that. If the coach comes down while you are trying to push the stand in position with the awning rod or some tool, if the stand is not under a body support point when it comes down it can cause serious damage to the coach.

There is no question you have to identify the source. Whether it is the air bag or fitting the fix is easy. If it is an air bag post it and I can walk you through the replacement. You will have to pull the wheel so plan on that.

[Pete]

Thanks Jon, I tried your suggestion with E.J. raising the front of the coach using the level low... It would not raise it high enough to get a stand underneath. I am sort of out of commission for the next couple of days with E.J's father being in the hospital, but will try to get my hands on a couple of jacks to lift the front so I can get the jack stands in place. I will be back in touch as soon as I can and will need your help when I do. Thanks again, Pete

[Jon Wehrenberg]

Pete, just to give you something to think about prior to starting the project........it appears you are going to have to pull the right front tire so you can get some access to what might be the leak. To do that you need the chassis in the fully raised position, and then you need to jack up the axle to get the tire off the ground. I think your vintage bus has front chassis support points ahead of and behind the axle. The stands were designed to go under the front support points. If you can jack the chassis at the rearmost support point so you can put the stands where they belong. Once that stand is in place everything gets safe and easy from that point on. Just be sure when jacking you are at the correct support point.

[MangoMike]

Pete,

This may give you some additional info if you have to change the bag.

http://www.prevoman.com/Pages/Air%20Bag%20Replacement/Airbagpg1.html




Mike

[Jon Wehrenberg]

I want to recommend a change to the procedure Mike posted. When Roger and I changed air bags we fought with the compression nut on the air hose fitting as Mike shows on my coach and I went so far as to modify a wrench so I would not have to damage the insulation in the wheel well.

When we did Roger's front air bags we made the following change which is OK'd by Prevost. I called to verify this.

Instead of trying to remove the compression nut on the fitting cut the air hose with a utility knife as close to the fitting as possible. Then the elbow at the top of the air bag can be unthreaded and removed. That makes removal of the air bag a 10 minute job once the wheel is removed. Trying to remove the compression nut is a laborious and time consuming job and easily eats up 30 minutes or more.

When re-installing the air bag install a brass street Ell in place of the one previously removed. Thread a 1/2" by 4 1/2" brass or copper nipple into the elbow. Thread a fitting that is 1/2 female pipe thread X 1/2 compression onto the nipple. Cut the tubing to the length necessary to mate up with the new fitting location.

This change brings the fittings out to the edge of the air bag where it is easy to get wrenches onto the fitting.

The bus Jim Chaloupka now owns has the fittings described and if he will take a picture of this and post it what I have described will be shown.

[Pete]

Thanks guys (Mike & Jon) and Jim (if he sends pictures), I haven't tackled the job yet, and probably won't for a few days, but I will probably need to enlist your help when I do.
Pete

[aggies09]

Best of luck Pete, keep us posted on your progress, air leaks appear to be my biggest nemesis in Prevost ownership..........................By the way, I was through beautiful Stanton earlier today and it looks pretty much like it did the last dozen times I was through there. Not much changes in Stanton.

[Pete]

About the only thing that changes are the number of "Old Soreheads"

[JIM CHALOUPKA]

Pete, here it is.

[Pete]

Jim, got it! Thanks a million!
Pete

[Pete]

Just finished the replacement of both front air bags. Thanks for your input Jon, and for the picture sent by Jim. I used my new jack stands (thanks again Jon) and they worked perfectly. I modified the air bags using the method Jon provided, and the pic Jim sent. The job was not as difficult as it may seem to be, and now that I have been through the change I would do it again without hesitation. One of the bags was dated 1994, and the other 1996. The 94 bag was the one that failed. It would be helpful if there was a date stamp on the bags so you cold get an idea of the age of the bag without removing it, as the mfg. date is on a label on the top of the bag.
After discussing with Jon, I replaced both bags with the (Goodyear P/N 1R11-244) Prevost P/N 630259. Prevost overnighted the bags in 1 day, (FYI, the old bags were Prevost P/N 63-0126). Again, thanks Jon for stopping what you were doing to help with your advice on this project. We have a great group of folks on this forum.

[Jon Wehrenberg]

Glad to help and I love it when a POG member finds working on the coach is not as hard as it may first appear.

I know I harp on air bags and how a failed air bag will shut you down. Pete's example is a good one. When we talked he understood how lucky he was that his air bag failure occurred at his home. If an air bag fails when you are on the road, the air system cannot make air fast enough and the bus is literally undriveable. I am changing my air bags out every 10 years regardless of condition because the coast of premature replacement is a whole lot less than the cost of having your bus winched up onto a trailer. If the front air bags are failed it is probable you will end up with damage to the coach because the front end cannot be raised to get the bus up onto the trailer.

I would rather eat bees than see my coach on a trailer or on the hook on a tow truck.

[antioch01]

Mike,
Have you sold the 97' Liberty ? I saw it on your site and we live in Plant City FL. Checked out Parliament and did not see it.
Thanks
Robert Johnson
904-225-8695
92' Liberty

[johnklopp]

For anyone that is looking for a torque multiplier, I found some on e-bay for $175 including 4 impact sockets. Not as elegant as the one pictured in MangoMikes post but should work well for our application.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=150533016227&viewitem=&sspagename=STRK%3AMEWNX%3AIT

[AprilWhine]

Thanks for the link.

Jim