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TRUST
Before I purchased my coach I sought out as much material and information about the Prevost coach and its mechanical workings as best I could. I am not a heavy duty mechanic nor do I posses the skills and knowledge who are in this profession. But I can and do understand mechanical concepts and applications, and with articles and information on this site and from others, feel reasonably informed when it comes to decisions regarding repairs etc. However, there is a large element of TRUST when dealing with experts, and I must profess there are some aspects of intimidation which goes with the territory.
So so much for this rambling…now to the guts of the issue. I am very fortunate to live close to a Prevost facility. I trust their work as it is my belief they are well trained and fair. I brought my coach in a few weeks ago to get an oil change, grease job and coolant flush. I told them to drain the tanks and put a new element in the drier. I also wanted them to fix an air leak I was experiencing in the right rear. Prevost did all the required work with the exception of the air leak. I spent close to $9k on a new front end (bushings and A arms), new tag lifting chambers and rebuild of my drier. They spent 12 hours labour trying to chase down the air leak on the rear end. I explained to them that they should concentrate their search to the norgrens, fittings, bags and ping tanks associated with the right rear end. The coach fully settles at the right rear within 7-8 hours, so I think the leak is substantial enough to detect. To say I am a little disappointed is an understatement. Of all of the repairs I wanted this leak fixed.
Prevost said to me that it wasn’t cost effective to proceed with further investigation……….I agreed. But now I have in my mind a dysfunctional coach in terms of its overall use.
My wife and I are headed down to Arizona for four weeks and hopefully the warmer weather will swell some of the rubber parts and limit the air loss associated with the right rear. I know this is not a fix.
I plan to go to Jeffs in October……3000 mile road trip and get this leak fixed, as he is the only expert I know and TRUST to repair this issue. Just so you know all the norgrens are 2 years old, and the bags are 5 years old. I really suspect it may be a fitting or multiple fittings…..but hey I am not an expert.
Sorry for the rant, but my wife is tired of my whining! Ahhhh……I feel much better.
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12 Replies
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Jeff wil find the leak, but if you don’t want to wait until October, swing by Prevost Ft Worth. They have great technicians there and can do the job.
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Allan, you know enough to know when your wallet is getting vacuumed. On your coach the leaning you describe is because there is a leak in a very concentrated area associated with that side. It is going to be in one of the 3 air bags, one of the associated Norgrens, both an internal leak such as out the exhaust on the 3 port valve between the two axles, or one visible externally blowing bubbles out of the end caps on the Norgrens. Other places can be the ping tanks or the fittings associated with the air bags and Norgrens.
There is a remote possibility the leak can be associated with the solenoid operated Norgren for that side’s exhaust in the steer compartment. That’s it. A flashlight, soapy water, a stethoscope or an ultrasonic leak detector is all needed to find the leak. But the key is the person doing the search has to understand the system.
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I feel your pain Allan the Prevost shops up here mostly work on the passenger Buses when you bring in a high end conversion Bus they have no clue. I take my Bus to a local truck shop these guys have been driving 18 wheelers all there lives after a DOT inspection oil change and service my bill is around $1000 and they point out the problems that need addressing. If you are going down south those guys know there stuff when it comes to Prevost Bus Conversion good luck safe travels. -
Allen,
What did they use to search for the leak? Soap? I spent $335 for a sonic Accutrac… we have found leaks that we never knew existed…..and did so within 30 minutes. If they did not use a sonic instrument, they were not trustworthy. The Accutrac can sense a leak that is only 1.5 ounces of a refrigerant per year… much less an air leak.. It finds the leaks quickly…cuts the shop time tremendously…
Not trying to make you feel bad but these guys toast me when they begin a replacement program until they finally get it right. No one can search for twelve hours… If there is noise in the shop… they have to have a system to use these devices…
Sorry for the experience that you had…
Did you replace all of the bushings on the independent suspension steering rods? Just wondering how difficult that was. I just did the entire upper and lower A arms…
Very best,
Pres
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Thanks everyone. I think the Prevost shop I have been dealing with have limited time on motorhomes. When I explained that the air to the bags is locked upon the ignition being turned off, and that they should concentrate their efforts between the five port norgren, bags, three port norgren, related fittings and associated ping tanks….all I got were blank faces. So given I am not the expert when it comes to these matters I deferred to Prevosts directions. They soaped the bags, valves and fittings but could not detect air loss. I did not mention the possibility of the norgrens that are located next to the coils in the steering compartment as it didn’t enter my mind as a possible source of the air leaks. I will look at these valves in the next few days.
As as for the front end, I cannot comment on how difficult it was to do as Prevost did the work. Suffice to say Prevost indicated it needed to be done and I am satisfied with their work on this particular aspect.
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I have no idea how you could actually spend 12 hours looking for a leak isolated to the right rear suspension system. If the suspension is going down in 7-8 hours, my experience has been the leak is substantial enough to find pretty easily. Go ahead and rant!
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Prevost Fort Worth chased my leaks on 2 separate trips. Never found them but did find my pocket book for a few thousand bucks. A few norgrens valves, ride height valves and other goodies. Then took it to Houston Prevost, Replaced Air bags and more air goodies including one of the Norgrens that was defective they put on in Ft Worth. Takes about a week but still goes down. Faster when cold temps. My coach is haunted.
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Allan,
When we bought our coach three years ago, new front air bags were installed by LIberty in Stuart, while we went through our orientation we noticed that the bus would go loose air overnight, after several attempts to find the issue we were sent to Prevost in Jacksonville were they replaced rear 5way Norgrens and we thought we had it fixed. It continued to leak, We then went to Nashville Prevost where they went through the coach. They found leaks at the fittings on the new air bags, Nashville suggested that pipe dope should not be used where metals are different on coupling fittings, Teflon tape was recommended. I spent the next several months reviewing and learning the air diagrams for my coach to completely understand my system. I replaced the rear air bags and all the short connecting lines that summer and had more leaks!! My own doing this time! To narrow down the leaks I used the air diagrams to understand the system and isolated zones to test with a gauge manifold, pressuring each area. It helped my focus leak testing on the zones that lost gauge pressure. My leaks were poorly tighten fittings, and I was able to find them methodically going through each zone. It’s not an enjoyable process, but there are so many possibilities for small leaks, targeted elimination has to work best. Oh by the way, studying PC feedback was extremely helpful including Jon’s detailed air system write up. There are issues that I have to take the coach to an outside shop for repair, but I try to do as much work as I can. Many hours can be charged while techs try to learn our unique coaches.
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Good job… I’ve done the same thing, if you isolate the systems and use shop air, you can find them.
As for aux air, I stopped driving myself nuts over leaks, mine will hold up for a couple days, that’s now good enough for me, I quit worrying about it. My belt bellows now hold air indefinitely thanks to a new check valve, thanks for the motivation BA…
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Don’t forget the control air for the tag brake interlock valve comes from the line supplying the tag air bag. If that R-12 valve leaks control air, your rear on that side will go down.I had small leaks leaks even after new Norgren and airbags, until I changed the R-12 valves. Now I stay up for weeks.
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Joe is correct, but that only applies to coaches with the system logic that required aux system pressure to prevent the tag axles from dumping air. Allan’s coach only requires the key to be off to “lock” air in his drive/tag axle air bags and even if aux pressure goes to zero his air bags should remain inflated.
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I am headed down to Arizona as we type. I will take a left on I40 and plan to be at Jeffs front door on March 22. I making a trip out it…….fix some leaks, get new tires and grab a slice of ELTC pizza.
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