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Urgent Help needed, ride height issue
Tried to leave on our summer trip today, and bus will not raise up to ride height from the position where the front was lowered to level the bus.
1. Can use level low to lower front end.
2. Can use level low to raise front end, but only part way, measures 11″ at bottom of fender skirt to ground. It should go higher and has in the past. It just stops at close to what ride height would be. Think it needs to be about 3/4″ higher.
3. If I use level low lower the front end, then put everthing in “road” postion the front end does not come up at all.
4. Took the center solenoid and valve off of the 5 stack and the relay does get hot and it does move the metal part of the valve inside the center stem.
5. I have a full 120 psi on all three air guages.
6. The center solenoid is 24 volt, do I get that at Liberty or does Prevost carry that?
7. If the center solenoid and valve are working what is the next thing I need to check?
I need to get on the road in the next 3 days to make it to all my reservations that I already have made.
Any help in trouble shooting would be appreciated.
I am currently looking at air diagrams and parts manual to see if I can figuire it out.
Thanks
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49 Replies
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Andre,
The center solenoid valvesdoes indeed control the ride height so you have to have the correct voltage coil (24V) and the solenoidalvehas to open, Check for air flow from the valve with the key on and the Liberty selector in the road posiition.
If you have the valve open with those conditions met the coach should go to ride height.
Some Liberty coaches had 12 volt solenoid valve coils on tjhe classic models so you need to get a new coil if that is the problem.
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Jon,
Thanks, I disconnected 1 of the air lines coming off of the center solenoid and with all switches set for road, tuned key on and air did come out of the center 5 stack valve.
So is my next item in line the norgren that is under the bus between the 2 front wheels? I think that is where that pilot line from the center stack goes.
Bus is up on jack stands.
Disconnected pilot air line from each 3 port norgrens under the bus that are just above the ride height valve, and turned ignition switch on. Air get to both 3 port norgrens.
So I guess I need to pull and replace each one and retest?
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Jon,
Pleae call me if you have time. I am stuck on this problem.
3 zero one 751 – 3 nine zero 7
Thanks
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Andre: Jon knows 1000x more about this than I do.
But let me share with you an experience I have had. My wife is obsessed with coming to ride height before we move anywhere. She judges this visually based on how high the front and rear mud flaps are off the ground. A couple of times she has said we’re not up all the way … and she was probably right. Most of these times I was 150 feet from the road, so I put the coach in gear and drove to the edge of the road at which point she deems that the coach is “up” all the way. I don’t know if having the transmission in gear or having the coach roll 100 to 150 feet makes a difference or not. But it appears to make a difference for me.
I encourage Jon to comment on my experience.
1984 96" with 8V92TA
(remodeled Liberty Coach)
Greenwood, MO -
I have talk to Jon, and my next step is to pull 2 3 port norgrens and check for water and or sludge.
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In the diagram above the red line is the pilot air signal to the two norgren valves by the leveling valve.The leveling valve should always have system air pressure to it and through it to the two norgren valves at port #1 on each valve. With no air to the pilots of the two valves the air from the leveling valve is blocked there.
When you pilot the two Norgren valves the spool valve inside slides and then the air from the levleing valve flows through the vlaves to ports #2 that are connected on each side to the front air bags.When you use the level low position to raise the front you do not activate the two Norgren valves. They are connected such that with the valves in the non-piloted condition, they allow air to be put into and out of the front air bags by means of the Norgren that is below the 5 stack manifold. So for the front to not rise both valves would have to fail at the same time which is highly unlikely.
Does the rear of the vehicle rise correctly with the drive position or by use of the level low controls? Perhaps we have a problem with the volume or pressure of the auxilary system?
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After speaking to Andre he has verified the pilot pneumatic signal is reaching the valves, so right now after learning he had water in his accessory system when he got the coach the suspicion is he may have a sludge and corrosion issue with the Norgren valves. He did all the correct trouble shooting up to the point of the verifying the Norgrens are “shifting” when they get the pilot signal. Tomorrow he will verify our suspicion.
I have worked on coaches with water damaged Norgren valves and if it is not sludge from corrosion reating an issue it could be water in the valve actuators creating a hydraulic lock. He will post the results.
The bus is on stands when he gets beneath it.
1984 96" with 8V92TA
(remodeled Liberty Coach)
Greenwood, MO -
Prevost Service,
Thanks so much for the quick response.
I just discovered that the rear does not come to ride height either.
If I use the level low to raise or lower the bus then turn level low off the bus stays at the same height that I put it at with the level low.
I have 120PSI of air on all three guages and have tried both engine compressor air and shop air thru the fitting in the rear enging compartment.
I bought this bus in Jan 2017 and I have discovered evidence that the AUX air system has had some water in it. I suspect that the 3 port norgrens in the front are gummed up and not passing enough volume and/or pressure for things to work. The shuttles inside not moving from pilot air??? Hope I am on the right track. The 2 front 3 port norgrens are getting pilot air when the key is on.
Is there a specific norgren in the rear I should check first??
Thanks again
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My experience has been the same as Dicks. Our bus always looks a bit low in front when airing up after sitting. It’s up but doesn’t sit up nice proud until we start running. After its up it stays up. So now Jon can tell two people who know 1000x less than him what that’s all about. I wonder if Andres experiencing the same phenomenon and it will come up when he gets rolling. Please keep us posted.
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Andre
I had the same problem and it was a bad pressure protection valve on the drivers bulkhead that supplies air to the height control valves.
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Terry,
Thanks for the info. Looking at the air diagram, it is a very good chance that is my problem. I just ordered one from Prevost and will replace it when it comes in tommorw. since that valve feeds all three ride height control valves, it sure seems like the likely candiate.
Thanks
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Andre,
Didn’t you tell me the rear does come to ride height?
Now I am confused because of so much conflicting information such as all gauges reading 120 which rules out a protection valve, air passing through the 3 solenoid valve down which rules out electrical or solenoid valve issues, and new Norgren valves in the rear.
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Jon,
When I spoke to you the rear was at ride height, but it had been there for weeks. Later in the day, I used level low to lower it, then tried to go to ride height, it did not move. Looking at the air diagram, the PP-2 valve next to the air filter in the drivers compartment has 2 lines coming off of it. One line feed directly to the front ride height valve, and has a T at the bulkead fitting that feeds a block in the rear that then feeds both rear ride height valves. It is the only part I can find that effects all 3 ride height valves. Since the front and the rear are not moving at all when I try to go to ride height, it must be that all three ride height valves have failed OR the PP-2 is not sending air to the ride height valves.
Now, I could be completly wrong. I am reading the air diagram on the computer screen and trying to follow the air flow from part to part. it is hard for my eyes to focus on the little lines and I lose my way. So everything I said above could be completly wrong.
Still looking, testing and thinking.
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Andre,
My discussion never covered a failed or faulty protection valve because in your very first post you stated you had 120 PSI on all three systems. You will not get accessory air pressure through the protection valve until you reach sufficient pressure in the primary and secondary systems, but the fact you have 120 PSI accessory air pressure rules that out. The only protection valve defect might be it fails to open at the correct pressure, but at 120 PSI in the accessory system you can rule that out as a suspension system issue.
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The protection valves between the air tanks are OK.
The PR-2 valve next to the norgren air filter under the drivers seat is the issue.
I disconnected the blue line that feeds the ride height valves and connected shop air directly to the blue line. Turned key on with everything set for “ROAD” and bus came up to ride height. So all I did was bypass the PR-2.
Look on the picture, the open line coming from the PR-2 has no air coming out and the AUX air tank is at 90PSI.
The shop air line is connected to the blue line feeding 120PSI shop air.
The PR-2 will be in in the morning and I should be abale to get on the road by noon.
As of right now, it looks like Terry hit the nail on the head.
Thanks to everyone for you help. Will post results in the morning when the new PR-2 is installed.
The picture needs to be turned 90 deg right.
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