Greener than Green newbies need some help please!

[wayne]

Some of you may recall that we purchased a 2001 Vantare D/S from Liberty in November. So far the experience has been over the top wonderful. Liberty went out of their way to make sure all was in like new order prior to us leaving the state.

After arriving home in Texas we found it necessary to make a trip to Prevost Fort Worth for an aux air leak....this was quickly fixed. Upon close inspection the tech determined that the air bag which keeps the engine belts taught needed to be changed....and so it was.

We are now home....north west of San Antonio, and have discovered that the air bag is losing air, causing the belts to sag. We have another month of "down time" before heading for Colorado for the summer, and would like to resolve this issue before leaving. Neither of us are skilled mechanics. We were told by a tech over the phone to "replace the check valve".....only problem is, we don't know where the check valve is or what it even looks like. duh! Feeling a little embarrassed to be writing this, but we are hoping for a little help troubleshooting this problem.

Thanks a bunch!!

jill

[Orren Zook]

Wayne,

On my Liberty there is an adjustable pressure regulator mounted over the rear engine doors that allows the pressure to be easily changed on that little bag. I'll try to get a picture posted for you in a little while.

[Jon Wehrenberg]

Jill, The first question I have is to verify when the engine is running the belts are tight. Start the bus, get the air pressures up to normal and shut off the bus. Are the belts tight, and if so, how long does it take for them to become loose. Please don't stick your hands in there it the engine is running.

Once you answer that question we can go from there.

Orren is correct, but one problem is you don't want to mess with the adjustment if the pressure is correct. There is a tire valve up there near the regulator. Chack that with a tire pressure gauge right after shutting off the engine and let us know what that pressure is. I have to look it up, but I think it needs to be 50 to 60 PSI (does anyone know off the top of their head?).

[wayne]

Thank you Jon and Orren for your quick responses and suggestions.
Right now, it is raining so we won't be going out to do any trouble shooting until the weather improves.
Jon, I remember seeing the suggested PSI on the knob near the pressure valve....you are correct, it's either 50 or 55.
So, I'll be getting back to you soon with the info you asked for.
Thanks again, really appreciate your help.
jill

[Jon Wehrenberg]

BTW, your description "greener than green newbies" suggests you think you are somehow not quite the equal of the members of this asylum. Actually I am not aware of any members of this collection of misfits who were born with the knowledge of these buses, or somehow magically come into possession of the skills and knowledge we all develop over time. Every one of us has learned these buses over time, and most of us have learned the lessons the hard way through the school of hard knocks.

So welcome to the asylum we call POG where you will never lack for answers to your questions, and on certain rare occasions some of those answers may actually be correct. If we don't know the answers we are not shy about making them up.

I'm only half kidding. You just have to figure out which half.

BTW, you don't have sheep down there in Texas do you? Some of the inmates on this forum are a little off level, about a half bubble to be exact and you need to keep your sheep safe and out of sight.

[wayne]

Jon, LOL....we DO have sheep, and despite the pouring rain I have just secured them well out of site...safe and sound from those inmates you refer to....thanks for the heads up!! We also have goats, 2 donkeys and a llama.

Thanks also for your encouraging words regarding the bus learning curve...we are both good listeners and quick learners so we hope to improve on our bus skills as time passes.
Thanks again....have a good evening.

[PLSNTVLE2]

I believe 50 psi is the number. Also try turning the key to the "on" position without starting the engine. This should supply air to the belt tensioner air bag. I usually turn on the key and wait 10 seconds before turning the key all the way to start. This allows the belts to become tight before the engine throws them off into the radiator.

I will bet that after shutting down the engine my belts are loose within a matter of a few hours.

Have fun........

[wayne]

Terry, as soon as we read this post we ran out the door with fingers crossed!
Unfortunately, turning the key to the "on" position does not work on our bus. It did nothing...bummer.
Thanks for the idea though.

[Danss]

my belts are always loose after sitting overnight. I turn the Aux. Air Comp on for about 3 or 4 minutes and the belts tighten up before cranking the engine. Dan

[truk4u]

Wayne,

You got all kinds of good suggestions, but my question is are you sure the belt bellows is the leaking source or is the aux system leaking down causing the belts to go slack? You said the air bag is losing air. Is that the same little air bag you had repaired and how do you know it's the leak source? Can you hear air leaking with the engine off or are you just thinking it is the cause because the belts go slack? You have many aux air sources and without the aux compressor running, it's pretty common to lose aux air and in some cases a very short time.

The XL2's may have a check valve to keep air in the bellows if the aux goes down, I'm not sure. I installed a check valve in an XL for that reason and as the aux air was depleted, the belt bellows stayed inflated.

[ajducote]

Here is a quick and easy check after you build up air pressure and turn off the engine.. Fill a spray bottle with water and dish washing soap. Shake well, and spray on all the parts everyone else has been telling you about. There is a valve and pressure regulator that controls air going to the small air bags. They are known to be potential leak points. Spray them down good and look for bubbles. Spray every connection you can find that is related to the belt tension system. Spray down the air bags and their fittings. If you do not find a leak there, then it gets a little harder. You have to figure out what else is on the aux air system and start spraying every air fitting you can find. It is possible to get things to the point where the aux air will stay up for weeks at a time. Just takes time and patience to find all the leaks. I found my last air leak in the toilet. I have a toilet that is flushed by air pressure and there was a fitting in the back of the toilet that had a very small leak.

Good luck.

[wayne]

Thanks to all of you who lent a hand in solving this problem.
When the skies cleared, we aired up the belt bag with our aux. compressor then started the engine. After all pressures were up, we shut her down and checked the air regulator pressure....it was at the recommended 50 psi.
We then took to spraying all fittings and the air bag with soapy water....we saw or heard nothing...appeared to have no air leaks.
So....we then decided to replace the check valve. Wayne removed it and drove to the nearest Napa store (80 miles.)in Hondo. They did not have the part, but suggested he check at a feed and grain store that also worked on trucks.
One of the mechanics took the check valve apart, cleared out a little dirt, replaced the "O" ring and stretched the spring a little bit before reassembling. He then thought it was fixed.
Wayne brought the check valve home, installed it and presto chango....problem solved. That all happened yesterday afternoon and the belts are still nice and snug! YIPPEE!!

Wayne called Prevost and ordered a new check valve just to have on hand. $40.

So....a happy end to our first in house repair job.

Thanks to all!!

[Prevost.Rick]

i just erased a 150 word paragragh, trying to explaine how to attack this problem,it,s easier to talk to you about this call me at 813-833-2284,or there is a old friend of mine that mobile serv. in san antonio,rick

[Jon Wehrenberg]

I think Wayne and Jill have it resolved. But in emails with Wayne and Jill it sounds like their ride height may need some adjusting so it might be helpful to them if they can hook up with a local guy familiar with Prevost coaches to help tweak the bus and get it right.

[Donnie_M]

Wayne, did you get your ride height adjusted? You never said anything about that and it looked good when I saw it. Did something change?

[wayne]

Hey Donnie,
Didn't have any problems with it until we got the bus home.
It doesn't automatically go to ride height any more.....I have to manually use the HWH system to bring it up.
Guess we'll continue to do this until we see you in the fall.

[Donnie_M]

Wayne, Are you saying nether the front or the rear will come up? If that's the case, the first two possibilities are 1. the "drive" solenoid on the level low manifold could be faulty. 2. the pressure protection valve right in front of the level low manifold could be corroded and not allowing air to pass to the leveling system. Do you get the green "travel" light on the HWH panel when you are in "drive" position and HWH is off?

The pressure protection valve in question can be checked very easy. There is a blue line that attaches to the top of the valve with a "press lock" fitting. The fitting has a brass ring that when you depress it fully, and sorta press inward on the line at the same time, then you can pull the line out of the fitting. If there is no air coming out, start the bus and build full air pressure. If there still is no air present, then that valve needs changed and it is real easy to do. My bet is that valve is the problem. Ill send you pics of it.

The pics I just sent you are of a newer coach and the valve has a brass fitting on it with 3 lines. Yours won't look like that. Yours should only have the one blue line on the output side. Call me for further instructions.

[Jon Wehrenberg]

To elaborate on what Donnie posted the ride height solenoid in question is the third one down (or the third one up if you are an optimist) in the five valve stack.

Lately there seems to have been a rash of coil failures. You can verify the coil is good or bad by either checking it for continuity, or if you do not want to do that, switch coils (leave the wires where they are originally) with any of the other four. It will take you about five or ten minutes to do this. If your bus goes to ride height then you know you have a bad coil. I don't remember the details, but Michael can help you with current pricing.

The solenoids in question are these in the steer compartment.

[Donnie_M]

BTW Wayne, when you find that there is no air coming out of that port where you removed the blue line, the prevost part #640439 pressure protection valve will fix ya right up! The valve is a PR2 and can be found at most truck parts places including some NAPA's.

[truk4u]

The Pressure Protection valve looks like this. The old ones were 60 psi, but the new ones are 75 psi.

6709

[Donnie_M]

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.

[Jon Wehrenberg]

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.

[Donnie_M]

[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).

[michaeldterry]

To elaborate on what Donnie posted the ride height solenoid in question is the third one down (or the third one up if you are an optimist) in the five valve stack.

Lately there seems to have been a rash of coil failures. You can verify the coil is good or bad by either checking it for continuity, or if you do not want to do that, switch coils (leave the wires where they are originally) with any of the other four. It will take you about five or ten minutes to do this. If your bus goes to ride height then you know you have a bad coil. I don't remember the details, but Michael can help you with current pricing.

The solenoids in question are these in the steer compartment.

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!" :rolleyes:

[Donnie_M]

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!" :rolleyes:
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?

[Jon Wehrenberg]

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.

[Donnie_M]

The only reason I asked was because the drive solenoid failure is only common in certain situations.

[Jon Wehrenberg]

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.

[Donnie_M]

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?

[Jon Wehrenberg]

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.

[truk4u]

I've done mine twice in almost 2 years, I think the heat gets the best of them since they're energized all the time when the key is on.

[Lawrence M.]

Wayne and Jill,
Where did you locate your check valve on the belt tension air line? I am having similar problems.

[Donnie_M]

Wayne and Jill,
Where did you locate your check valve on the belt tension air line? I am having similar problems.The check valve is located directly on the input on the back side of the manifold where your red lever you turn to release the pressure. Look behind and follow the air line to the valve body. As I told Wayne, pull it apart and clean it.

[Lawrence M.]

Thank you! Appreciate your help. Stay with it!

Larry Dahlin