The Leans

[Jon Wehrenberg]

Under the POG III thread Ben suggested a session on the leans. Trying to trouble shoot or identify what specifically is causing your coach to lean is like trying to define how high is up.

When your coach leans it is because you are leaking air.

End of training session

The leans begin when your valves start to leak, or your air bags start to leak, or it gets cold outside. All of the causes can be addressed but there is no simple way to explain how to fix your specific problem for a number of reasons. The primary reason is because your converter may have handled the leveling system on your coach in a manner different from my converter. Another reason it is not so simple to identify a specific cause is because there are so many places that can be a leak source and every one of them can be the problem or only one of them is the problem.

Several on this forum have had success dealing with the leans. Maybe we can accumulate the advice here and get Ben started on his quest to solve his problem.

[MangoMike]

I'll be glad to add to the lean quest.

I'm on that mission now and have replaced most my Norgren valves and hitting the last couple today in an effort to stem a rear leak. It's probably the most persistent problem that faces Prevost owners, well at least the ones 5+ years old. And Jon is right there is no simple fix, you just have to be persistent and keep on tracking them down. I'll be real interested in seeing Jon's final evaluation on his new snifter.

I'm doing my best to fully understand the whole system, it's relationship to Norgren valves and converter vs Prevost installs. I'm hoping with that knowledge it will be easier to understand the nature of finding a particular leak.

Will keep you posted.

Mike

[dale farley]

I started my search for a leak today, and I found one of my air bags that is leaking when it has maximum pressure on it. Unfortunately, it is on my tag axle, so I assume that would not cause my coach to lean. I also used some ramps that I made a couple days ago. They are made from 3/4" plywood and seem to work fine. They give me about 10" more clearance, so I can do most things with this much working room. I made a couple pictures if anyone is interested.

I have noticed my coach does not lean all the time. It seems to be worse when I raise the right side up to its maximum height. I stayed under it for several hours today and noticed no significant drop on either side. When I quit for the day, I raised it to the maximum, and it has dropped about 3/4" on the right side in 1 1/2 hours. There is definitely a difference in where I leave my level switch as to what happens. There have been times when I have leveled the coach and it would drop several inches on the right side in just a few minutes.

One thing I don't understand is why it drops about the same both front and rear unless I have a leak in both places. In the last 1 12 hours it has dropped about 3/4" in the rear and a little over 1/2" in the front. Does this mean I have a leak at both ends or is there a leaking valve that is common to both ends?

Although I could easily see the leak using a bubble mixture, I could not hear it using a hose as a stethoscope. It only leaked while the pressure is at max, then it tapers off to almost no leak at all. I have ordered one of the ultrasonic leak detectors like Jon is using, so I will let you know if it helps in my quest to find all the leaks. Dale

[MangoMike]

RR,

I've been spending a lot time under da bus trying to full understand the whole level low system. So here's a couple of thoughts. Which may or may not be true, but it's what I figured out so far.

This pertains to the 97 liberty xl classic:
Front air bags and rear air bags are totally independent of each other in the Level Low mode.

There are 5 norgren valves handling the rear of the bus. Two in front of the drive wheels (center coach) add air to the rear bags - one for each side. These are 5 port valves.

driveNorg_2909.jpg

In the cavern between the drive and the tags on each side wall are 3 port norgrens. One for each side. This dumps the air from the rear bags. There are 3 bags on each side in the rear, which includes the tag. I'm not sure if the three are all ganged together. I know the two by the drive wheels are. The third three port norgren on the passenger side is some sort of control valve that works the spool valve in some of the rear main norgrens -not sure at this point which ones.

tagNorg_3677.jpg

Left one is the dump valve and the right is the spool controller.

I'm going to get a handle on this yet.

Mike

[Joe Cannarozzi]

Roadrunner
The front drops with the rear drops on one side or the other when it leaks because the front has only 1 height valve dead center. If ya think about that for a minute you'll get it. When the front leaks that will never affect the rear.
.

[MangoMike]

Joe is correct The front bags have only one ride height valve for both as you motor down the road.

rideHeight_3011.jpg
Ride Height - 1 up front, 2 in the rear

But the Level Low system employs at least two Norgrens up front, one for each side.

frontNorg_2840.jpg
Located in the steering bay.

Again all converters different as to their approach to Leveling. This is Liberty's.

Mike

Note to Harry: I'm trying to use the site as intended

[dale farley]

Well, from what Mike and Joe are saying, I assume my problem could be caused by the leak in my one rear bag. Of course, I am not sure if the tag bag is ganged with the other two bags on each side. I really wouldn't think it would be since it has to operate rather independently, but maybe it is.

Mike, are those valves in your pictures the Norgren valves? I have read every book I have and no where do they mention a Norgren valve. Is that just the brand name for the control valves?

[Joe Cannarozzi]

I am curious. Our 86 does not have these norgrin valves and the bus functions just fine without them. I believe we have all the same capabilities as the busses with them, the ability to level the bus while camping with the suspension. Were these components added just to complicate things or what

[MangoMike]

Dale,

Honestly I don't know if the Tag are ganged with the rest or not. It's something I would like to find out to add to the understanding of the system.

Norgrens are a brand name and the photo of the two valves are the Norgrens.

Joe,

I'm not sure when/if any changes were made. My knowledge base is solely limited to my Liberty at this point.

But the person who unlocks the Rosetta stone about the whole leveling airbag system on theses busses is going to be one popular guy on POG. I nominate Winchester - he's got plenty of free time to be poking around the belly of the beast.

Mike

[dale farley]

Joe, I am thinking the same thing about my 93. I don't think I have any Norgrens, but I do have a leak. Dale