-
Driver rear sitting on tires
I own a 1997 XL45 Entertainer bought about two years ago. This is my first time posting here and I’m SO glad I found this site! I’ve had several issues with the coach which I’ve had to figure out on my own or pay a lot of different repair shops tons more $ than I probably should have to help further their on the job training, but I’m not made of money so I’m finding more and more courage to take on these issues myself. This site has been very helpful so far! That being said, I’M DYIN OVA HERE! Air problems, air problems and oh yea, air problems! After reading many of the posts on this thread I’ve realized I’m not alone, so I’m hoping someone out there has encountered this same issue and can point me in the right direction.
Here’s the issue. Since I’ve owned it, the bus has never held air or “stayed up” after shutting the engine off for longer than maybe an hour. After that, it sits on the tires all around. I’ve had several small (audible) air leaks repaired under the bus in fittings and hoses (primary and auxillary) and most recently had the air dryer replaced (which I just found out is supposed to be done about every two years). I am very prudent at draining the rear and front air drains about every 1000 miles or so. I had the air unloader replaced a while back. At this moment, the bus is in the shop at Prevost in Fort Worth and I’m getting ready to pay a nice bill for replacing both rear air holding tanks (one had a leak so just to be safe I’m replacing both). For the last 2000 miles, we have been having to manually air up the bus (with the switch in the cockpit) every few minutes to keep the drivers rear from grinding on the tires…as we’re doing 65 miles an hour down the road. Not a very good feeling to have, but we didn’t have many options. Once the new tanks are in place, it’s my hope that the bus will return to holding air at an acceptable level while we’re driving, but I’m not expecting it to fix the airing down while we’re parked.
So my question is: what could be causing the bus to air up fine when we’re driving but lose air so fast when we’re parked? I guess I should also note that before the air tank issue, the bus would air up from sitting on the tires to acceptable ride height in around 5 minutes when started. When parked, it seems that the passenger front holds the longest (maybe 5 hours) but the rear and driver front seem to be sitting on the tires within an hour after shut down. Any help in the right direction is greatly appreciated, and thanks to all of you who participate in this wonderful exchange of free information to help each other out!
-
8 Replies
-
Since you are at Prevost Ft Worth, have them find the air leaks. They can give you estimates to fix, and you can prioritize the repairs.
-
I’m not clear on what you mean by “air up the bus from the switch on the dash.” Are you saying you need to use the Level-Low controler to keep the rear end at driving height? If so, it sounds more like a leveling valve problem than an air problem. Or perhaps the valve is damaged and leaking so you have both problems. Unless I misunderstand your system, you do not have an auxillary compressor to fill the suspension. Therefore, if there is enough air to operate the Level-Low, there should be sufficient air to keep the bus at drive height. Get Prevost to diagnose and fix it before you hit the road again. Air problems such as you describe are serious and potentially dangerous.
-
above see this section. there is a good tutorial on systems you are working on. when key is switched to on the center coil on stack in drivers side lower steering compartment should have power. this supplies air to manual leveling valves. 2 on rear and one on front.
-
Please go to your profile and enable us to contact you via email.
Your problem in the most blunt terms is you have an underloved coach and it is probable there is no silver bullet. You have issues that can be solved, but just from your limited description there seems to be multiple problems.
Prevost knows what they are doing relative to your issues and can resolve them, but they are not going to be inexpensive. I can tell you for sure that if you think you are saving money by nibbling away at the problem one little issue at a time, you will get it all done eventually, but it is my opinion that the quickest way is to start at the Norgren solenoid valve stack in the steer compartment and systematically follow the air from there, dealing with leaks along the way until you have reached the rear air bags. I suspect if you plan on all 8 new air bags, and all Norgren spool valves, and possibly all ride height valves your bus will not have the problems you are now having for 10 years or more.
I suggest biting the bullet and just planning on all of the work listed above because chasing leaks on an old system is an effective way to drain your wallet, but it is a waste of time if the issues are widespread and you are going to end up with almost all new stuff anyway.
If you don’t want to spend the money and just want to find the big leaks making the bus drop as quickly as it does, keep in mind you have at a minimum two areas that need attention, If your suspension was leak free or relatively leak free you could drain all air pressure in your coach and the coach would remain at the driving height. When you turn the key off it locks air in the air bags via the Norgren spool valves.
If your accessory air pressure is draining quickly you also have leaks in the accessory system unrelated to the suspension.
Your most serious problem, that of the coach dropping while you are driving at highway speeds is more than likely a defective coil or solenoid valve in the 5 solenoid valve stack on the rear bulkhead in the steer compartment. That is a cheap fix that takes a few minutes, but it will not fix the other issues.
There are shops less expensive than Prevost if you do not do your own work. Prevost service centers tend to be pricey but they do back up the work they do for a year. Other shops that do repairs tend to be less expensive, but I strongly suggest you avoid any shop that does not work almost exclusively on Prevost conversion. Even though replacing air bags and valves is not rocket science your coach’s previous owners may have screwed with the suspension system to put a band aid on problems so the bus could keep going, and you need a shop that knows the systems well enough to fix it right.
-
prevostcar.com tech pub last letter in your serial # plus last 4 digits. Example mine is W-6553 V= 1997
-
Had mine in several times over the years after I first bought at Prevost Fort Worth and Houston after they first opened, with this issue. Gave them Carte Blanche and after several thousand dollars and 3 way, 5 way, leveling valves, fittings and hose’s and who knows what else it will still start settling after about 3 or 4 days. Takes about a week before it hits the stops on back. As far as Prevost is concerned Had to adjust there bill as they had to replace 5 ways again they said were bad on a second or third trip back in to shop a couple years back within about a month as I kept telling them to fix at all cost. . Sounds like you have a hellava leak and ought to be able to hear that puppy. Good luck on the fix.
PS,
It’s down on the back after about a week of sitting in the barn. Rats!
-
Just as general information for everyone, Prevost has had a suspension system evolution and initially it was necessary to maintain aux or accessory air pressure to prevent the suspension from settling down in the rear. In the mid niineties the system logic was modified so the aux or accessory air system pressure could drop to zero and the suspension system would still retain its air pressure in all air bags (assuming no leaks).
When the independent front suspension was introduced more changes to the system were made.
What has never changed is that regardless of the system design or logic the coach has three individual suspension systems that only share an air supply. And that air supply is blocked, as is the air in the suspension system when the key is off (except on some converter modified systems). So the way to stop the coach from leaning or settling down is to stop the leaks. The leaks are going to be through the Norgren valves, at the fittings, or at the air bags. Whether the leak is in the front system, the left rear system or the right rear system it will be from the Norgren valve that functions as the control to supply or deplete air to the air bags associated with that system and everywhere in between.
We’ve discussed this before but it bears repeating. Leaks are difficult to find in some instances and the actual finding of the leak may involve a person’s ears, a stethoscope or soapy water or an ultrasonic leak detector. Finding leaks takes time and patience and a lot of money unless you do the leak detection work yourself. The starting point however is there must be a basic understanding of the supension system and its operating logic.
-
Also forgot to mention in post above, Prevost said they weren’t bad, but had them also replace all Air bags on one of the first trips a few years back when I was chasing leaks. You will find winter is a killer on settling as summer is not as bad with leaks as all rubber and plastic goodies swell with the heat.
Log in to reply.