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Stuck and not sure what to do
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ck that level height valve.. That arm looks as if it could be up on the hose. That might explain the fact that this bag deflated and pinched itself on bottom mount. When front end twist with your straight axle it could bind dumping all the air out of the bag. been there on valve binding. good pictures
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This may not be the answer but it could be a clue.
Around your coach year Prevost had to address an issue with some converters overloading the steer axle. Their response if my memory is correct was to change to larger air bags in the front that were jokingly called Mae Wests. Additionally there was a service bulletin at the time adding a second set of shocks on the steer axle I presume to address rebound.
I do not know the original or Mae West air bag part numbers, but it is possible your air bags are wrong for your coach. Obviously when that bag is replaced someone is going to have to watch for clearances as the coach front end is run up and down through all possible situations ranging from coach level, leaning left, leaning right, wheels left right and center.
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That’s the first thing I thought of, wrong bag, assuming axle and components are not shifting which is doubtful.
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That’s an interesting comment about bag size. There was a different size bag many, many years ago. When one of the bags failed it was something like a 109 bag but Prevost looked up the chassis and part and said the bag should have been a 108 or something but it’s certainly smaller. The reason I changed bags in the first place last year was the other bag blew while driving on I-70 in Denver and I decided to change both as a precaution. These are the same as those bags but different than the ones that were on there previously.
What confuses me most is that the bag would have had to completely collapse (no air) to get flat enough to get pinched between the frame and the base of the air bag. I will have to get more information about the valve mentioned above as well. The ride height valve has a straight rod that connects to a hard point on the chassis. Are you saying this could be on the axle and that the axle movement is causing our loss of air or that somehow that air line is pushing on the arm of the valve?
I do have 4 shocks up front as well. You will see a yellow and a blue. It’s supposed to be 2 blues on each axle but that’s a whole different Prevost can of worms! This setup works well while driving.
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those leveling valves have a built in delay before they change to allow going around corners. If that rod comes loose or hangs on something that gives them a false signal as what to do. They are less than $50. I think it is dumping air and letting bag go flat and pinch.I’ll check and see if I still have part numbers that were screw up around then..Most bags last at least 10 yr. FWIW
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if that level valve were up that high(pic) it would be dumping air fast..
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The bags we “had” were less than 10 years old but maybe 6-7 years and they were the same bags we have today. We were traveling at less than 5 MPH when this happened and in both cases we were making a hard left hand turn. Prevost had replaced the original bags at an FMCA rally many, many years ago but they replaced them with the same bags that were installed on the coach at the time. It was only 6-7 years ago that the bags were changed out to the current bag. Never had a problem for 6-7 years so I am trying to figure out what might have changed, suddenly.
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What Bob said makes sense to me. Check the operation of that ride height valve.
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The front leveling valve is a single valve and it would dump air on both bags at the same time. If that were the case, you would think both bags would be rubbing on the frame. You would definitely know the entire front end lowered.
I keep going back to your pictures. It looks like the damage to the bag was more to the lower portion of the bag itself and if you match that with the mark on the frame, the bag would have to be squished to a point that the internal stop would limit the travel. Is it possible the internal stop is crushed allowing the bag to compress beyond it’s design point? I have cut open bags and found the internal stop in crumbles.
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What is your VIN of your coach…I want to look at something as if the air bag had air in it then the pinch point on the bag doesn’t appear to make sense…
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On a solid axle coach the ride height valve as Bob mentions is a time delay Haldex brand and it is located at the top center of the axle area. For it to hit the air bag would not be possible.
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The VIN is J0001415 . The air bag is not touching the ride height valve as they are too far apart but the bag must be losing all air as it tilts far enough to the right and it’s clear that something (the air bag is the only thing close) is rubbing against the chassis often enough to leave some bare metal. The only way that happens that I can imagine is the bag is completely flattens like you would while trying to install it with no air there.
If the bag cannot support the weight of the front axle, is it possible for the air to blow back past the height control valve or some similar happening? When similar events have happened in the past (without bag damage) I have had to use the Level Low system to get enough air back in the bag to drive.
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The one time mine failed to air up (5 years ago) and had to use level low to raise and drive to Prevost and they replaced a coil under drivers area. Never have had a torn bag issue.
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In the picture it looks like the linkage arm on the valve could be catching the hose. (As Bob said) Has that been eliminated as an issue?
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I would strongly urge you to pull up the service bulletin relating to the change to Mae West air bags.
The more I look at the photos the more I am beginning to understand. First, that coach was one of the ones modified to get the second set of shocks on the steer axle. I suspect the greater diameter air bags are being used and if in fact they are the “Mae Wests” someone may have failed to recognize clearance issues with the greater diameter.
Replacing the air bags again is going to produce the same results again so don’t do it unless clearance is assured.
As a side note Country Coach was one of the converters producing nose heavy coaches that forced the modifications Prevost made, via a change in parts or via a serviced bulletin. Those changes were not required on all conversions and it might be possible your VIN might be shown as requiring the larger diameter air bags. If you get the right air bags for your coach there will be no future repeats of the problem, but to get the front to raise and maintain ride height in the front you may have to put the stuff in the front bay in the trunk of your toad to get weight off that axle.
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