prevost air systems

[robertglines1]

Anyone needing help needs to visit prevostcommunity.com  look under articles  for a further  info.  My system(and most others)  The aux last much longer than a few hours without the aux air compressor running... During normal use about 2to 3 minutes every 12 to 14 hrs..this includes air doors etc.. of course you can make anything use more air..  Some mechanics jack air pressures up above specks, take short cuts and modify systems. That only damage the end result.  This is my opinion only!  I did not say the Prevost system is good. Just said it can be workable.    Bob

[Jon]

To add to what Bob posted, the Prevost suspension system is complex, has a lot of fittings that have the potential to leak, and it has evolved over the years to the point that there are a lot of variations. But as he correctly points out taking shortcuts to keep it working such as jacking up air pressure is just asking for trouble. If you have a Prevost and the pneumatic system is driving you crazy there is help out there available for the asking.

[luvrbus]

It's a great system but just a little bit over engineered 

[robertglines1]

rite now my 98 system stays up almost a week after complete rehab-- before dropping down to 75# ( do not have the aux air compressor hooked up yet) so I do have a small leak.. My opinion not worth the chase.  I do not have any  aux air appliance in the system other than prevost items.   Factory level low system--norgren/elect over air system..... Bob

[Jon]

It's a great system but just a little bit over engineered 

It is hard to argue with Clifford on that point, however I can see how Prevost created such a system. If it is a seated coach it may have the kneeling feature which adds some complexity. But when Prevost adapted the system to be capable of leveling a coach converted to a motor home the level of complexity went way up.

I am not familiar with other makes, but just on the chassis alone air is used for a lot of other features such as belt tensioning, the EGR system, the retarder, door lock, driver's seat, etc. and with the change from compression fittings to push in fittings air gets to be a problem that has to be addressed far too much.

[sledhead]

I am not familiar with other makes, but just on the chassis alone air is used for a lot of other features such as belt tensioning, the EGR system, the retarder, door lock, driver's seat, etc. and with the change from compression fittings to push in fittings air gets to be a problem that has to be addressed far too much.

On my MCI much the same less the EGR , the retarder.      Air  Door lock , basement door locks , belt tensioner
8 air bags , rad shutters .

I did remove the air bags from the system to install a leveling system and with a little work that system has not leaked . YET           dave

[Boomer]

On older MCI's you can eliminate the leaks at the fan belt and A/C belt tensioners by simply installing turnbuckles.

[Boomer]

Maurice Gagne, Prevost North America Service Mgr. was in our shop once while we were installing new Norgrens on one of our late model H's.  He highly recommended installing new Norgren valves once a year, even though that is not on the PM schedule.  Of course this was for revenue cars, not motorhomes but in MH use they should be changed periodically for trouble free use.  I always took anything Maurice said as gospel, there is absolutely nothing he does not know about any of their products.  We had a QR valve on the rear stick once too when trying to raise from low bouy.

[Jon]

Unfortunately as a long term Prevost owner who has done all my own work for about 18 or 19 years now I can agree the Norgrens do need  replacement from time to time, but after having read tens of thousands of post about Prevost coaches over the years I do know this for sure. The leaks in the suspension are going to come from the fittings, Norgrens or the air bags. On extremely rare occasions an air line might be compromised but that is rare.

So what does Prevost do? They use push in fittings instead of compression fittings so they need to now focus on the fittings instead of the Norgrens or air bags. We encourage all owners to replace all push in fittings with compression any time service work is done.

Anecdotal evidence suggests that air bags start to have failures around 10 years of age. Prevost is silent on when to replace them and they suggest when one fails. They all don't fail be leaking slowly, some burst, so I have been changing all my air bags on my coaches on their 10th birthday. I throw out a lot of good air bags that way, but I also sleep better at night. Norgrens seem to start leaking around that time also so when I change air bags I also change Norgrens. They can be replaced with new or refurnished with a new spool assembly or just new O rings.

What I disagree with is Mr. Gagne's failure to recognize a leak free suspension on a Prevost is one you don't mess with. If it ain't broke, don't fix it, because in every case I know of after replacing components like Norgren valves almost an equal amount of time is spent chasing the new leaks that were created when fittings were threaded into the valves or air bags.

[jetart]

I can confirm Jon's comment about 10 years being about the limit for airbags.  I changed out all 10 of mine last spring and they all had 1999 date codes.  I don't know when the were installed but I can say I'm glad they are off my coach.  I also replaced my brake diaphragms and they had similar date codes and let's just say the rubber had severe cracking (not good!!!)  My air brake lines might have been original as they were really bad and I could not find a date code on the hose.  If you own a Prevost make sure you budget replacement of anything rubber every 10 or so years. (if not for your sake - the person stopped I front of you)
Dan