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Bus Leans
Our 2001 H345 Marathon leans to the left cold weather seams likely it has manual Prevoist leveling sys have replaced Noreen valve checked air lines and air bags can’t find any leaks need advice thanks Busman
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5 Replies
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Dear Bus,
Welcome to our world. You are learning one of the sad facts relating to Prevost ownership. The first being if you are going to have leaks, they show up first as temperatures drop. Then they get worse and the coach leaks all the time.
Your coach is about the right age to start showing leaks. As a practice I decided that at about 10 years of age I replace air bags and Norgren valves. Keep in mind I have been called anal so what works for me may not work for you. I have learned from experience that from 10 years of age my coaches have started to show their age. I had an air bag fail at 10 years and Norgrens that never leaked seemed to start showing leaks as temps dropped so rather than spend a substantial amount of time chasing leaks as they occur, I just replaced all the air bags, Norgrens, and push in air fittings in my suspension.
I do my own work so my cost to do that is limited to parts. If you have others do that type of work you can expect about 10 hours for air bags and about 6 or 7 for Norgren valves. Or you can choose to chase your specific leaks. But keep in mind that is likely to end up with considerable more labor content than just getting the parts replaced. You will NEVER be able to find all air bag or Norgren leaks with soapy water, and you do need to go to the Prevost webinars and related articles on this site to understand the system and the best ways to diagnose leak locations.
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Just a general comment that needs to be repeated often.
Early vintage coaches (prior to around 94 or 95) had a system logic that required the aux. air system to remain pressurized to prevent the suspension valves from dumping tag axle air. That is no longer the case on later models. Coaches produced after the above dates do not require any air pressure in any of the systems to prevent “the leans”.
If a coach with a leak free suspension system is leveled or left at the ride height, air can be bled to zero pressure from the air systems and the coach should remain level or at ride height. While it is desirable to keep a coach leak free and chasing leaks throughout the coach is beneficial, if the focus is on preventing “the leans” don’t bother with any leak detection anywhere except in the components and fittings associated with the area of the suspension that is losing air.
I have noted some offer advice to check for leaks in areas unrelated to the suspension and while that never hurts, fixing those leaks will not cure the problems relating to suspension leaks. Also, try to understand that to identify some leaks a device such as Hector’s Texas bubbler or a device such as used by Prevost to pressurize and monitor pressures may be the only way to find some leaks. Further try to understand in some cases a leak that affect the rear can be in the front steer compartment so a little understanding of the systems helps.
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FYI, I have replaced several leaking air tank drain cocks, the most recent being the cause of right rear leans.
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I found several of my leaks were drain cocks as well.
Accordingly, I strongly recommend replacing all of them along with the air bags and Norgren valves at the same time. This will go a long way to curing your leans the first time around and should remain trouble free for years to come. It also doesn’t hurt to get rid of all those push-on fittings as well. They rarely re-seal truly leak free.
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Now that all of us have had the benefit of Robert Hitt explaining about our suspension system, leaks, and trouble shooting he makes it clear that the “ping” tanks on our suspension could just as easily have plugs in place of the drain valves because of the lack of need to drain them.
If anyone does have any trouble with the valves it is likely just as easy to put in a plug rather than a new drain valve.
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