leaning coach syndrome

[wrongagain]

Help,the bus is leaning.
I have recently replaced all the air bags, the front and rear leveling valves, all valves and blocks under the drivers seat area, two leaking 3 way valves in the rear of the coach.
Everything that can be seen has been soaped, front, rear, under, over, between, etc.
Nothing, not even a little, shows any signs of leaking or bubbles, that includes all air lines new or old, aux or main, yet that corner still drops in about 6 hours.
Including myself a total of 4 people "3 are prevost mechanics" have gone over this with gallons of soapy stuff.
And yes, all this started with the replacement process, which also was the same time as northeast cold winter weather.
I would blame the cold but only one corner drops, not the whole bus.
Where else does one look for leaks in a coach that only loses air in the drivers side rear.

[JIM CHALOUPKA]

Ed, just a hunch, but it sounds like the only thing you didn't change was the air. What I mean by that is you are still getting the same air and supplied by the same source. This may be oily wet and dirty!
You further indicated that the cold seemed to bring on the condition. My guess is that you have moisture in your air supply and it is playing havoc with the system. You also may have other contaminants in the system. A small spec/particle is all that is necessary to make a valve malfunction. It could have entered the system at the time any component was removed and exchanged.
I suppose you will tell me that you completely cleaned the system and blew out all the lines with Nitrogen.
Well one more thing did you test all the valves before you installed them?
What you need to do now is figure out which valve or component is at fault and remove it and test it. This is not easy to do and that is one reason that Jon W recommends that new valves be tested before installation!

[wrongagain]

System is dry and clean.
It could be a bad new valve.
We took the supply off the drivers rear leveling valve to see if the check was holding or bleeding back into the tank, and it held.
To tell you the truth I am about to buy a ultrasonic leak detector.
I know they are around a $1000.00 but right now cost is not the object, and since I dont know anyone who I can borrow one from.
I have reached the gotta do what you gotta do stage of this leak hunt.

[JIM CHALOUPKA]

Ed, there is a quality leak detector offered by Grainger:
Amprobe TMULD-300
http://www.grainger.com/Grainger/wwg/productIndex.shtml?operator=keywordSearch&search_type=itemnum&QueryString=5hw14&submit.x=17&submit.y=9

Hope this helps. I think it is the way to go.

Better order some of the bus supports from Jon. :cool:

[Jon Wehrenberg]

Wrong Again.....welcome to my world. And everybody else's too.

Is the coach kept where it is cold right now?

Do you intend to do any work on this yourself or are you willing to let others pick your pockets?

The reason the bus is leaning is likely related to a leak in an airbag in the rear on the side it leans to, or the five port valve (and possibly the three port valve near the tag) on that side. Answer the above and then lets see if we can walk through the analysis and help you understand why you can't see bubbles. Shame on Prevost by the way.

If I don't answer right away it is because I'm out of the house this morning.

[Joe Cannarozzi]

Ed

Guessing, It could be a defective air bag. If you can not detect it at normal ride height engage the leveling system and jack that corner all the way up and check the bag itself. All around the bottom bell and also that upper seam where the bag meets that top plate.

The bag forward of the drives may require removing your inner mud flap to access it but no big deal, I have removed that without pulling the tires.

If it's going down in 6 hours that is a large enough leak that you should be able to find it.

The cold is precisely the time we should be looking for these leaks, it's when they like to show themselves.

Many times it isn't till after I have gone back to a problem numerous times that I then spot it. Stay on it and I am confident you will find it.

The fact that it did not start till after the above mentioned changes gives you a pretty good head start.

Are you having fun yet?

[Jon Wehrenberg]

Ed and Joe....if the leak is around the bottom "can" the "piston" that the air bag rolls over will prevent soapy water from getting at the bottom seam and will also prevent anyone from seeing the bubbles even if it did get to that seam.

The ride height valve is definitely not a part of this problem. The five port valve blocks air coming from the air bags so for the ride height valve to be a part of the problem the 5 port would have to leak, and the ride height would also have to leak when its arm was in the neutral position.

One question I forgot to ask, Ed.....is your aux air system pressurized? Is the pump turned on to maintain pressure. Some early model XLs would dump air if aux system pressure went below 30 PSI. I do not think that is it, but want to check. Another quick check is to raise the tag axle, bring the entire air system up to pressure and shut the bus down and see what happens. This check eliminates the tag axle air bag as a possible leaker (or confirms it) and it also eliminates the three port tag axle Norgren valve (or confirms it is the problem.)

Last question before I go....does your coach have an "automatic" leveling feature, and when you shut the bus down are you leaving it in this position? Explain your shut down process as well as your leveling system. Each coach has variations between Prevost chassis years, converters and converters options.

BTW, Ed. There are four ways to detect leaks...ears, stethoscope, soapy water, and an ultrasonic leak detector. No one way will work all the time. An internal valve leak will never be detected with soapy water, and conversely a pin hole leak in an air bag bladder will never be heard by an ultrasonic leak detector. And you need patience. This problem is isolated to just a few things so it should be easily located if the diagnosis is done methodically.

BTW, If Prevost did this work you described the good news is they stand behind their work so you should be done spending money, and if you don't mind more visits to Camp Prevost they ultimately bear the responsibility for correcting this problem.

[wrongagain]

Yes, it outside now.
All the stuff that was replaced was leaking and or non functioning, and was not part of this new leak hunt, the leak is a result of the new parts, it didnt leak down as fast with the old parts.
In a couple hours when my neighbors are all awake I will start it go high in the rear and resoap the bags.
And as far as prevost picking pockets,... there was 2 guys and myself on it for 6 hours wednesday, and there was no charge of any kind, just sorry we cant find it and see if what we did do changes it at all.
It did not change it, still a 6 hour leak.

[wrongagain]

All the 3 and 5 port blocks have been checked a jillion times.
The tag seems to be operating normal, goes up, stays up, etc.
Aux air holds pressure going by the gauges, a couple of days.
The 2 gauges on the dash hold air for a day.
The corner of the bus drops in hours.
Has the normal self adjusting ride height while driving.
Has the level low system with the 4 way rotary know and up-down switch.
I have tried leaving it in various positions trying to outsmart the leak.
Keeping in mind all this stuff worked before they replaced the extremely cracked air bags, after that it became the leak hunt.
Right now I have tried the stethoscopes, soapy water, and ears, but I always have a little air leak noise going on from years of shooting without ear protection.
Dont have a leak detector, but I am starting to see one in my future.

[merle&louise]

Ed,

I have a leak detector, give me your address and I'll mail it to you. It is just like Jon's. I bought it but never used it. I will be traveling until Sunday, but I could mail it to you first thing Monday morning.:D

[dalej]

Tuga,


That is such a nice thing to see from a fellow POG member, it's what it's all about!

ps.. go back to page 1

[wrongagain]

Thank you,
Your offer to let me use your leak detector is more than generous, but,...
I cannot accept your offer, as much as I appreciate your help, when I borrow tools, I break tools.
Without fail it will be somehow broken, scuffed up, or mutated in some fashion and then I will buying you a replacement thats not quite like it because of some new and improved refinement that you wont like.
Long story short you will hate me, I will be buying a replacement for you instead of myself.
"Ask me how I know"
Now,... All that being said if you would share with me what kind it is so I can buy and break my own, then that would be help I can accept, and this way we will all remain friends.
And again, thanks for the very generous offer.
Ed

[Jon Wehrenberg]

Ed,

I have to generalize because of the variations of the different converters, but with your tag axle up, key off, leveling system controls off or in the normal driving position if the coach still leans it is probable you can take the tag axle three port valve and the tag axle air bag off places to look.

I suggest you start there.

If it does not lean you know the problem was in the tag air bag or three port valve.

If it does lean there is a high probability it is in the five port valve or the two drive axle air bags on that side.

Bear in mind I think this is sound advice, but if Prevost or the converter has a different system or valve arrangement than what I am envisioning it may be lousy advice.

The cold air is advantageous right now because any leaks show up more quickly and are greater in cold temperatures. Another advantage is the leans are always occurring in one direction so you can essentially ignore everything else.

Just for grins, because it is so simple and easy to cure, take a T10 torx screw driver and remove the solenoids in the 4 or 5 valve assembly in the steer compartment and listen for and tighten any leaks that may be occuring there by tightening the two diagonal screws a little. With the key off BTW none of these solenoid valves should be energized if the system is like the systems in today's coaches.

If the leak is around the bottom of an air bag you will go nuts trying to find it. If you are really interested in verifying the air bags are leak free the only real way to do it is to make up a little plumbing assembly that can be connected to the three air bags in series and that you can connect to air pressure to raise the bus, and then close off by turning a valve. I would suggest connecting at the last air bag such as at the tag axle, and plugging the fitting going into the five port valve with a cap. You literally need to be a detective to get the right lines or you have to take each air bag out and test it individually. If you do this and it doesn't leak down the problem lies with the valves.

As an alternative you can remove the valves and bench test them (again with home made plumbing to verify the valve opens and then closes leak free) to isolate the problem also. If you opt to do either, do it in the cold. You may not have any leaks when it warms up.

[merle&louise]

Thank you,
Your offer to let me use your leak detector is more than generous, but,...
I cannot accept your offer, as much as I appreciate your help, when I borrow tools, I break tools.
Without fail it will be somehow broken, scuffed up, or mutated in some fashion and then I will buying you a replacement thats not quite like it because of some new and improved refinement that you wont like.
Long story short you will hate me, I will be buying a replacement for you instead of myself.
"Ask me how I know"
Now,... All that being said if you would share with me what kind it is so I can buy and break my own, then that would be help I can accept, and this way we will all remain friends.
And again, thanks for the very generous offer.
Ed


Ed,

If you look at Grainger.com and search part # 5HW14 you will find AMPROBE leak detector, and it sells for $221.64. I am either not using it correctly or it doesn't work. I find soapy water spray works much better. Jon likes his so I am probably not using mine correctly. I used Jon's stethescope to find leaks and that works much better than the AMPROBE leak detector IMO.

I understand not wanting to borrow tools - I feel the same way, I also tend to break things!:D

Good luck.:)

[wrongagain]

Thanks again for the offer, it was appreciated.
The detectors I have been looking at are around $1000.00, kind of pricey for this project but since I can use it for the business "HVAC" so it will be a good investment.
I havent had much time to fool with it because of the holiday, and now 2 days of rain.
I am going to florida in 2 days so this leaking project is on hold till I get back.
Over the holiday it was in the teens and 20's outside so there was a nice lean going, so much so I think the front on the same side is going down but a much slower rate.
Passengers side still did not move at all.
Thanks to everyone for the help and advice, maybe in a couple of weeks I can get back on the project.

[Jon Wehrenberg]

Ed,

This is the one I use. You may not need the sound generator which is good for testing door seals when stationary but has nothing to do with the type of leaks you are dealing with.

The good news is you do not have to look any further than the 3 air bags and a few valves on the rear LH side.

If the air bag is leaking via a pin hole in the rubber portion the leak detector will not find it.

http://www.testequipmentdepot.com/amprobe/envirotesters/uld300_tmuld.htm

[wrongagain]

This is the one I am looking at, it is the one that seems to used most in my industry.
I just never really needed one before now.
But since I am going to buy one I'm sure I will find all sorts of uses for it.


http://www.reliabilitydirectstore.com/AccuTrak-VPE-1000-Ultrasonic-Inspection-System-p/sup-vpe-1000.htm

[Jon Wehrenberg]

They really like their leak detector. I can tell by the price.

[JIM CHALOUPKA]

They really like their leak detector. I can tell by the price.

It can be had cheaper in Connecticut.
http://www.pemco1.com/accutrak.html

http://www.pemco1.com/contact.html

Same tool different profit motive.:rolleyes: :D

[ajhaig]

Ed,

Did you ever get this resolved?

Have you taken the bus on a trip yet?

Merry X-mas.

AJ

[wrongagain]

PM sent to you AJ

Been busy fine tuning my snow removal techniques.
Still have not bought the ultrasonic leak detector.
Just got back from seeing mickey mouse.
Nothing like driving 20 plus hours straight to beat a snowstorm.

[Sid Tuls]

I need a little info. Went to check on the bus at the bus barn and notice that all the air was dumped in the front but not the rear of the bus. This is the longest that it has sat since I bought it last year. It's been in there about 4 weeks. I started it up and it went right back up. Is this normal or is there a problem that needs to be looked at. Thanks








Sid & Judy Tuls
2007 Thompson XL11 D/S

[garyde]

Hi Sid. First check to see if the leveling switches were left in the drive position or in manual. If it was left in the drive position, your Norgren valve is probably the culprit.

[Sid Tuls]

Thanks Gary, It was in the drive poistion. Do I need to go Mira Loma to have that fixed? I'am heading to Amarrilo on Tuesday and can stop and have them look at it. Is there a form that has more info on that valve? More importantly how did you and your family survive the Fires? Thanks for getting back to me.











Sid & Judy Tuls
2007 Thompson XL11 D/S

[garyde]

Read this:http://www.prevost-stuff.com/prevostair.htm
Trouble shooting can be costly, so at the very least you should have a general understanding of the system so a mechanic does not spend needless hours chasing down the trouble. If you know where the valves are located, it will help you to help them.

[Jon Wehrenberg]

Sid.....

The Prevost standard is that if it sits without settling for 3 days or more it is acceptable. We can discuss whether that is reasonable or not until the bovines return home, but if you asked Prevost to repair the leans and it met that standard when they were finished removing a lot of Ben Franklins from your wallet they would not make any further repairs under warranty or without expecting you to count out some more Lewbucks.

So to specifically address what appears to be your concerns, first I would say if it took two weeks or even a month for it to settle you have a leak, but based on its size it will be a challenge to identify. I am not suggesting it cannot be done, and I don't think it can't be resolved, but it is not a leak that a brief inspection will find.

Hector's power point program is close enough to your model coach as to give you a sense of what components may be contributing to the leak. Your coach has accumulator tanks at each air bag (not shown on Hector's program) so in addition to the potential leak being at the five port Norgren or the three port Norgren in the steer compartment, you could have a leak at the fittings or the air bags or the accumulator tank drain.

Personally, until it gets worse I would ignore the leaks. Now I know a guy with a highly polished and detailed engine will find this to be heresy, but given the number of potential sources for leaks in the aux air system, and the fact that finding them is a time consuming challenge I would suggest you get in the habit of lowering the bus all the way down when you store it and make like you have no leaks. We certainly will not tell anybody. And the time saved chasing leaks can be spent polishing the engine.

[BrianE]

Sid,

You have heard from the Guru. Trying to eliminate all leaks will drive you nuts. Jon has also made available to us his very nice bus stands. When storing your bus between trips, deflated airbags will compress and may develop stress cracks over time. Propping the bus chassis on blocks or Jon's stands before airing down will prevent these stress points from developing.

[MangoMike]

Sid,

I think if you can get 2-3 weeks without the leans you're walking on water.

Welcome to the club.

Mike

[Sid Tuls]

Thanks to everyone for the replys. This POG forum is great help to new owners. Yes, Jon has help me out before and it was just like he said! Also enjoy the ribbing that goes on the site(that's not beef rib's). I guess I'll have to make plans to go to a POG rally. Thanks again.
P.S. What are Lewbucks????









Sid & Judy Tuls
2007 Thompson XL11 D/S
Visalia,Calif. / Amarrilo,Texas

[Jon Wehrenberg]

Lewbucks are very hard earned dollars grudgingly spent. Guys that have earned their buses and who know the value of money spend Lewbucks.

The US Government that conficates our money will never know what a Lewbuck is. Named after our own resident curmudgeon.