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case of the leans, need information on service
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The switch from compression fittings to the push in fittings may have been a real advantage to Prevost as a manufacturer, but we owners are paying dearly for that change.
Several PC members have more recent experience than I do, but I know how difficult it is to chase leaks. I did it on 2 coaches to the point they were virtually leak free. Not completely, but so close the aux air pressure gauge would take days to move, and the bus never leaned once leveled.
But within a couple of years both coaches were presenting leaks again. When I change air bags and brake chambers next year, part of the project will be to change every fitting involved with my air bags, ping tanks, Norgren valves, or any part of the systems I work on to compression fittings. I will then likely start the process of changing every fitting over to compression and leak checking the systems.
The important thing for all owners to understand is if you ask a service provider to cure your air leak problems it can very expensive very fast. In the case of an older coach I will not even consider chasing leaks. As others have said if the coach has 10 years or more on the suspension components I bite the bullet and just replace everything because it takes so long to find leaks, it is just faster to replace parts, all of which are going to need replacement anyway. The fittings that are push in will automaticaly be replaced with compression that can be reused over and over and once they are leak free they remain leak free.
It is a hard pill to swallow when we first realize our “million mile” coaches need expensive maintenance work such as air bags, but for any quality product to have a long life maintenance has to be done. One thing that has been a huge benefit for me is the willingness to do my own work. The learning process, which still goes on, is a very steep learning curve, but once you get into it a little the logic that has gone into our coaches becomes evident and then stuff starts to be more easily understood. But no matter hwo much maintenance costs most will agree it is far better both in terms of helping to retain resale value, but also in preventing the expensive road calls when the bus breaks.
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Jon makes a good point. I just had my air bags, brake chambers and norgren valves changed in June. The only thing it did for my leans was change the direction it leaned. The left side always leaned and it rarely does now. The front never went down in 6 years and it does in hours now.
However, the peace of mind that I enjoy while driving all over the country is worth the price of the recent work. This old thing may leave me stranded the next time the wheels roll but at least I know I have done my best to prevent a break down because of air bags, brake chambers and norgrens.
Once I get a place to work on this thing myself I can start investigating why it leans. Until then I will deal with it and do the best I can to keep it road worthy.
Davy
Edit: This comment was poorly written. I hope I made it clearer below. I left it as is here so the conversation would make sense.
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Davy funny you should mention that. My old coach didn’t lean when I first got it years ago but second trip wouldn’t go to ride height. Took to shop and left it. They called in a couple days and said as ready. Arranged flight to go get her and they called next morning and said “it’s leaning on left side” it’s been fun since then. Now only on right side, I think it’s haunted.
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If you replace parts of your suspension systems such as the valves or air bags, and the coach leans when it never did before there is a leak. I realize I am stating the obvious, but if you have made the repairs you are disturbing a large number of fittings and it is also possible one of the components that were replaced may have been defective.
I know of one owner that had two leaky brand new air bags in a row. The third one was leak free.
Don’t accept the leans. Isolating a leak in the suspensions is not the easiest thing in the world, but it is also not overly difficult. It is a pain, but if you already went to the trouble of trying to fix the coach, go the extra step and insure it really is fixed.
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My comment above was poorly written.
It may have appreared that I was disparaging the work that was completed on my bus in June. That could not be further from my intention. Jeff and his guys replaced the airbags, brake chambers and norgrens and did great job and at a price point I could afford. I understood then that this was not a fix for all my air problems but it certainly gets me a lot closer. This whole thing has been a process and the process is not finished yet. As I was driving cross country a few weeks ago I felt much better than usual knowing those major components had been replaced as well as the air dryer and compressor.
I was trying to say in my previous comment that these things do take continual maintenance and that the learning curve for me has been and still is very steep. I am very glad for the progress that has been made in bringing my old bus up to snuff and I could not have brought it this far without the help on here.
I have a ways to go in understanding the rest of the system and then having time and opportunity to chase the aggravating leaks that cause it to lean. I will probably never be to the place that I can be comfortable changing the major components that have been changed. Thank God for Jeff. But it would be a joy to understand it better than I do and enough to stop the pesky leans would be a bonus.
For now I do not even have a way to get underneath it.
Davy
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I just put six new air bags on back one new bag was leaking had to take out and put another new one in now it does not leak , u can have new parts leak too , that’s why u have to check after u do the work , u just can’t replace parts and think it’s all good u have to check the new parts!!!!!!!!
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I hate replacing air bags and Norgrens. I don’t want anyone to think once they are replaced problems go away.
First, the number of fittings involved is pretty large which means every fitting you touch or replace is a potential leak, just because you didn’t put the right amount of sealer compound or thread tape in place or you didn’t tighten it the right number of turns or the air hose has a slight nick in it you did not see.
As Peter and I both pointed out you could have a bad air bag, and those leaks are not only very hard to find, the process of eliminating every other possible leak location is time consuming and difficult. We always pick the low hanging fruit so the hard stuff ends up being checked last.
I have yet to do a perfect air bag and Norgren valve replacement. I always end up screwing something up and have a bad part, a leaky joint or even a new fitting with an invisible hair line crack.
Between my 3 coaches, and coaches I have helped work on I have changed air bags and valves 6 time and maybe next year when I change mine out I will get it right for once. Maybe.
Second, don’t worry about anyone casting aspersions about Jeff’s work. I am almost certain Jeff has the same frustrations regarding those suspension repairs. The tough part for him unlike shade tree do-it-yourselfers like me is he is up against the clock so he not only has to be perfect the first time, but he has to be fast if he expects to make money. I have spent as much time chasing leaks as it took to change stuff out.
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Just saw your comment Tom, about my LED tail lights, They came from http://www.ibpindustries.com
Jeff was correcting my “Leans” problem, which is now corrected. Has not leaned since I left his place last Friday. The main item leaking was the drain valves on my tanks. Jeff said they were not leaking at the threads, nor the exhaust port on the valve, but where the thumb knob goes through the valve.
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Like everything else with rubber used to make a seal the valves on the bottom of the air tanks are subject to leakage as they age. They are an often overlooked source of leaks.
But one comment that needs to be understood……….even if you drain every pound of air pressure from every single air tank in the coach the coach will not lean if the suspension is leak free. If the coach leans it has nothing to do with anything other than the air bags, associated Norgren valves or the fittings within that system. (The ping tanks at each air bag on later model coaches are within the suspension system and must hold air pressure, and their drain valves if leaking will cause the leans. Those valves are likely what Jeff repaired.)
And our coaches do not have a single suspension system. They have three suspension systems, a front, left rear and right rear. They only share a single air supply and even if that air supply has zero pressure the suspensions are unaffected.
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LED posts moved to Electrical.
Sorry for the thread creep..
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we got the leans fixed. put new compression fittings on. We do have a leaking lift chamber on the left side. Prevost replaced the one on the right back in July. I need to order a new chamber. Right now the temps have been below freezing at night. I am losing air as the bus settled in 2 days. I am figuring it is the cold but…. it shall be check again when we return to Commonwealth Coach in Hopewell VA. My heart interface inverters are only putting out 93 volts. We are replacing them with magnums. The webasto needs to be fully serviced. I was unaware of the monthy run rule. I need to know where to get parts. The learning curve is steep , expensive but rewarding. I appricate the communitys help.
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Cold weather definitely will cause air leaks, but only on a coach that has them anyway. If the coach leaks down or leans over a period of time when it is cold, it will do the same thing when it is warm, but generally over a longer period of time. The rubber seals harden to an extent in the cold making us all aware of the minor leaks that really didn’t appear when it was warmer.
The rear lift chambers are nothing more than a #36 brake chamber, available at any truck parts house for probably under $50.
As far as running monthly, it is not a rule but there are benefits if it is done properly. I generally will not even start my coach if I have nowhere to go, regardless of how long it is sitting. The greatest wear on an engine occurs on restart after it has been sitting because over time the oil lubricating the surfaces drains away and for the first few seconds and prior to the oil recirculating there is less lubrication at those wear points. But if you do follow a monthly start schedule, bring everything up to temperature. In other words run the engine long enough to completely heat soak not only the engine, but the associated parts such as the exhaust to drive out the moisture that is created when it is started from cold.
Allowing the engine to run at fast idle is insufficient to generate the required temps, so a 30 minute or more drive at highway speeds generally does the trick. The key is getting it all hot, including the transmission.
There is a side benefit to doing a monthly exercise of the coach. Our conversions have a lot of valves that control the suspensions as you are aware. Internally they have a spool that shuttles back and forth to either maintain the driving height or to enable you to level the coach at a campsite. If during a monthly coach exercise you also cycle the level low system through its full range of motions you are moving the internal parts in the Norgren valves and keeping them free. None of this exercising is needed if the coach air system is well maintained and free of moisture, but if the air systems have any moisture it begins the process of corroding the polished aluminum interior of the Norgren valves. That in turn makes the valves “sticky” because an O ring sitting in one spot with moisture present seems to end up binding, kind of like an old unused engine whose rings are stuck to the cylinder wall.
So the routine monthly warm ups do have a benefit. If your air system is bone dry however there probably is not a measurable benefit from a monthly drive and if you don’t want to go for a drive, you can use the aux compressor to air up the aux system and you can exercise the Norgren valves without ever moving the coach.
Mango Mike at one time had a great tutorial on Webasto. Does anyone know how to access it. That’s a good weekend project, simple, and puts it back into great shape.
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Mango’s Webasto is in our articles, good help is hard to find!
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My bus is staying level but my aux air tank empties within an hour or two. My brakess air gauges don’t drop quite as fast but they loose most of their air within several hours. I just read this thread in it’s entirety so I already know the system can be empty and it will stay level if that part of the suspension is working properly. My questino is to ask whether there is a first place I might check in cosideration of how fast it’s loosing air. I think I already know that a major leak could be on any of the components and that the clue I provide is not worth anything.
Jeff
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Jeff,
Jon has a good overview doc for diagnosis in the article section.
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