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A Puzzlement
Recently, we have experienced a problem with the coach. For some reason, it began to simply kneel down completely in the front. It loses all of its’ air in the front bags. They were replaced some time ago and do not seem to leak. The rear holds its’ own…no leaks.
We have done everything possible to determine why it goes down. We can find no leaks and we hear no noise. It goes down evenly. It does not “sag” to either side. We have sprayed the valves over and over…
Interestingly, when we cranked up the coach and raised it to an above “ride height” level… it would not leak down… in clearer words, it did not leak while lifted up..
Tonight, after three hours of spraying, etc., the mechanic and I gave up and resorted to the PC group…
Any thoughts ???
Thank you…
Pres
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12 Replies
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The air system is not separated from side to side on the front suspension, that’s why it doesn’t lean. The front only has one ride height valve. If it stays up past normal, that says that either the ride height valve may be leaking at ride height, or the valve that controls the front is bad.
I’m sure Jon will have you an answer shortly.
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Pres, I think your coach might have an HWH system on top of the standard Prevost level low.
If I understand the HWH you can turn it off so it does not function. If that is the case try bringing the coach to the driving height and see if it leaks down with the HWH turned off . If it does the HWH can be ruled out as a contributor. I believe it is active with the key off and it is working to keep the coach level.
If the coach sags in the front it means the leak is isolated to the air bags in the front, the fittings, the ping tanks (if you are IFS equipped), the ping tank valves, and the Norgrens that control the front. If it is an internal leak in a Norgren valve it may be exhausting in a place unexpected such out of the end caps, or internally past the spool and out the three port exhaust valve on the rear steer compartment bulkhead. Sart there because is it an easy check. There will be a three port Norgren that has an exhaust port on the bottom. It may have an open port or a small bronze “muffler”. that is where a leaky valve will show up.
The good news is if you can get your hands on a borrowed ultrasonic leak detector, everything but the air bags will make a sound it will detect at the leak, internal or external.
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Jerry,
I will advise the mechanic tomorrow… I guess we will start to replace valves…
Best and thank you….,
Pres
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Thank you Jon… I will pretend that I understand what you said but will print this out for the mechanic to be sure he gets it…
Pres
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Pres,
I believe Jon is correct and you have an HWH leveling system. I only know enough to be dangerous but maybe the little I know will help your search. The HWH on my coach can be isolated from the Prevost system by a shut off value located inside the drivers service door. I discovered it while chasing leaks from the aux compressor and generally entertaining myself. I think you will figure it out visually. There is also a 20 amp fuse on my coach associated with the HWH located in the ECC inside the first bay which I also assume you have. Maybe that would be too simple but might be worth a try. If not there will be a fuse somewhere. The leveling system brain (?) is on the floor of the steering compartment and a “solenoid valve air” to quote CC for the HWH is also in the the steer compartment and finally the sending unit is buried in the 2nd bay behind a panel.
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Pres,
I looked at your signature and you do have IFS so you are going to have ping tanks. Make sure you include them in your search. If yours is a southern coach corrosion on ping tanks is not an issue, but coaches that have had exposure to the salt from snow covered roads have had corrosion under the straps and leaks have been found there.
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Just a FYI, when searching for a leak with an ultrasonic detector, if you apply an amplifier (soapy water, or leak detection liquid) even the air bag leaks can be detected. The bubbles popping will emit sound that is detectable by the detector. Like Jon said, if you are fortunate get your hands on a leak detector, you will find the leak.
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Pres where you getting the work done at ?????
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might be leaking at stack—5 selenoid stack in steering compartment or 3 port norgren located in board from them–referring to factory system—-un modified
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If it is leaking at the stack it is probable the accessory pressure will drop to zero, but the air bag pressure should be locked in based on the design of the system. It will not hurt to verify the manifold and its valves are not leaking.
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One thing for sure, when the weather turns cold, you’ll discover your air and coolant leaks.
I think you rulled led out the air bags Pres since it stays up with level low.
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Thanks to all … we will solve the mystery…
The coach is in great shape with no corrosion… just keeping up with everyday issues…
Peter…
The work is being done by a mobile mehanic that we have used for 12 years… He is very trust worthy and has worked on Prevosts quite a bit through his carreer… He is very dependable and does good work. In most situations, he has a very solid understanding of the issues and can “figure out” what we need to do to solve the issues at hand.
I generally go to the warehouse and assist when I have the time… On other mechanic work like axle seals, brakes, etc., or any body work and painting…. I use Freightliner Trucks’ Body Shop here in Houston. When it involves the engine or transmission, I go to Stewart & Stevenson in Houston or United Engines in Oklahoma City. …
Jeff at ETLC I am certain would do excellent work but he is a long way away. It is at least a two and half day run to Tennessee for me….
Pres
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