That would be the one! With Wayne complaining about his air leaks, all those "extra hours" the aux compressor was running, more moisture than the Prevost dryer in the fjb can handle (along with improper maintenance of the air system from the previous owner) was entering the system. He will be chasing a few more valves before it's over. This valve is installed to stop the flow of air from the main tanks in the event of an air bag/line failure.
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When a bus reaches 10 years of age, regardless of prior maintenance an owner that wants to have trouble free enjoyment of his suspension and level-low system should bite the bullet and replace all air bags, and all Norgren valves.
While it is relatively easy to check for leaks in the 3 suspension systems (front, LH rear, RH rear) by 10 years the air bags are nearing the end of their life based on anecdotal evidence. Even if they can have a few more years of life eked out of them an air bag failure means the bus is done driving until the failed bag is replaced. An air bag failure shuts you down just as effectively as a failed motor unless the owner does not mind banging his coach down the road with minimal ground clearance and no springs.
The Norgrens both the three port and five port valves are also affected by age and begin leaking, imperceptibly at first, but then very noticeable when it gets cold out. Finding leaks in old Norgrens is a major project because they can leak out the end caps, through the valve, or both. If it sounds like a lot of money, it is actually the most cost effective way to deal with or prevent the leans. By the time a leak in an old system is identified the owner realizes it would have been just as cheap to replace everything in the whole system. Many owners have posted horror stories of mechanics at $100 an hour spraying soapy water looking for leaks, most of which will never be revealed that way.
A set of air bags, installed should be $1100 for the air bags, and around $100 to $125 each for installation for a total cost of around $2100. For little more than $1000 parts, plus 1/2 to 3/4 hour of labor per valve all Norgrens can be replaced. I would suspect Prevost prices for these tasks and parts to be considerably higher, but we have many sponsors who are willing to do this work for the above costs. BTW if you don't know how old your brake chambers are that's a good time to get them replaced, although an on road failure of a brake chamber diaphragm is not a show stopper and can temporarily be dealt with until a replacement can be installed.
Donnie hits on something few owners are aware of. If the bus air system is the only source of pressurized air the suspension system and its myriad of valves tend to be well protected against moisture, assuming the owner is draining the air tanks routinely and keeping the air dryer maintained. But depending on an aux air compressor for an extended period without servicing the dinky little moisture traps typically found is a guaranteed way to get premature failure of aux air system components, and especially those sensitive to corrosion due to moisture in the system. Chasing the problems which could be caused once moisture enters the system is a nightmare. I had one owner tell me his leveling system failed to function because he had hydraulic lock due to water in his valves.
[QUOTE=Jon Wehrenberg;64722
Donnie hits on something few owners are aware of. If the bus air system is the only source of pressurized air the suspension system and its myriad of valves tend to be well protected against moisture, assuming the owner is draining the air tanks routinely and keeping the air dryer maintained. But depending on an aux air compressor for an extended period without servicing the dinky little moisture traps typically found is a guaranteed way to get premature failure of aux air system components, and especially those sensitive to corrosion due to moisture in the system. Chasing the problems which could be caused once moisture enters the system is a nightmare. I had one owner tell me his leveling system failed to function because he had hydraulic lock due to water in his valves.[/QUOTE]
We have been adding an additional tank on the H's down beside the windshield washer fluid container (since H's are 99.5% of the vehicles that we see...lol) and separating the Vantare systems from the Prevost "aux" system. The only real benefit of the aux compressor is generator air bags when dry camping. Sure the older coaches have air pocket doors (and then electric, and then air again for a short time, and finally back to electric) but if you are going to stay stationary for any length of time, you should just turn the compressor off and flip the pocket door bypass and slide them by hand. Some people with pets also like to use the stepwell sliding cover, so air is required for that. I firmly believe the systems from the converter should remain as isolated as possible from the Prevost system. This way, if you do take your coach to a Prevost service center, they can't throw the converter under the "bus"...lol... immediately blaming the problem on the converter. If it were me, I would plumb the gen air bags like the good ole days...tie the fronts together and the rears together and plumb them to service ports above the gen box with a gauge for each side and add air manually when needed. And if you should have to add air, fix the leak! This way you could leave the compressor off while sitting and/or dry camping and not introduce so much moisture in the system plus save the power used by the 110v compressor (on Vantare systems).
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The price of the complete 5 valve solenoid manifold stack assembly (p/n 641205) was $323.91 plus applicable tax & shipping when I bought one on 4/19/2010. The individual coils/valves (p/n 641929) were $32.59 each if you want to order spares.Originally Posted by Jon Wehrenberg
Depending on the vintage of your coach, replacing the whole manifold assembly can be the easiest way to fix failed solenoids/coils/valves or be a royal PITA because of the configuration and orientation of the current manifold block. On my coach (1995 chassis), installing the new manifold stack intact would have required completely reorienting the air connections and the electrical connections to mount it to the steering bay bulkhead where it already resided. After much head scratching and gnashing of teeth, we just decided to swap the individual coils/solenoid valves from the old and new manifolds. The end result was the same and I didn't have to figure out how to reroute the air line connections and electrical connections to accomodate the different configuration of the updated part that is now being sold/shipped.
Had I known then what I know now, I would have saved myself a few bucks and just bought 5 of the individual coils/solenoid valves for $32.59 each ($162.95 total instead of $323.91). Live and learn, eh? "You have to pay to play!"
Michael, if you don't mind me asking, what problem were you having to cause you to change out the manifold assy. Also, do you have the HWH auto level pad?The price of the complete 5 valve solenoid manifold stack assembly (p/n 641205) was $323.91 plus applicable tax & shipping when I bought one on 4/19/2010. The individual coils/valves (p/n 641929) were $32.59 each if you want to order spares.
Depending on the vintage of your coach, replacing the whole manifold assembly can be the easiest way to fix failed solenoids/coils/valves or be a royal PITA because of the configuration and orientation of the current manifold block. On my coach (1995 chassis), installing the new manifold stack intact would have required completely reorienting the air connections and the electrical connections to mount it to the steering bay bulkhead where it already resided. After much head scratching and gnashing of teeth, we just decided to swap the individual coils/solenoid valves from the old and new manifolds. The end result was the same and I didn't have to figure out how to reroute the air line connections and electrical connections to accomodate the different configuration of the updated part that is now being sold/shipped.
Had I known then what I know now, I would have saved myself a few bucks and just bought 5 of the individual coils/solenoid valves for $32.59 each ($162.95 total instead of $323.91). Live and learn, eh? "You have to pay to play!"
Senior Member
Michael did not swap the entire manifold, but did change out all the valves and coils. What prompted the replacement of the valves and coils was a failure of the third one down (or the third one up) because the bus would not go into the driving height position.
His vintage coach is on the cusp of having other suspension system components begin failing and now has some problem with leans so he will soon replace the air bags, and I presume the norgren spool valves.
I recommended that because when a bus reaches the age of his the original components are near the end of their life cycle based on the numerous bits of anecdotal evidence that has been posted here over the years.
The only reason I asked was because the drive solenoid failure is only common in certain situations.
Senior Member
I am not up to speed on why, but over the last several years numerous POG members have experienced a failure of the drive coil. I do know the wattage of the coils supplied by Prevost has varied. Since that is the only coil energized whenever the coach is in motion the frequent failures may be attributed to heat, but I have no proof of that.
Typically the failure occurs without warning, and just when the owner wants to drive. So far I have not been aware of any failures that have occurred while the coach was being driven. We have covered the diagnosis and emergency fix here on the forum as well as several phone calls I have gotten in which I walked the owner through the issue based on his mechanical skills and available tools.
Drive solenoid failures tend to be more common with one specific conversion. I have changed 1 drive solenoid in the last 10 years, can you guess the year model and conversion?
Senior Member
A sampling of one probably is not a good indicator of a trend. Of the conversions I remember one was a Vantare (Michael's) the other was an early model Marathon with four solenoids, and I do not know the converter of the other two I was involved with. The trend to me (joking here) is they were all on XL's.
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