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Leak at ft height control valve
When I command front high position coach responds but at completion of raising, after returning Liberty front suspension toggle switch to neutral position, the front suspension leaks down through the exhaust hose on the ride height control valve. If I understand Jon’s article, this indicates an internal failure in the ride height valve.
Two questions: 1. Do you’ll agree with diagnosis? 2. If I’m replacing height control valve, I understand Prevost makes an immediate response valve and a delayed response valve. What are the pros/cons of each?
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15 Replies
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Yes. It sounds like the valve is bad, but I think you are leaking through the Norgren 5 port valve. Look there first because air to the ride height valve should have been blocked.
I believe your ride height valves are the fast acting because you have IFS and ping tanks. They are square bodied black plastic, whereas the time delay Haldex ride height valves are a cast metal irregular configuration.
Do you have moisture in the aux system? It sounds like the Norgren is not fully closing if you can hear air.
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If air goes through the 5-port first and should be blocked, then the ride control valve is normal because it SHOULD bleed air when the front is raised, right? The schematic in your tutorial is tough to read; is there another source somewhere?
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Jeol, I go to the Prevost pneumatic and blow that up to get the detail. If you highlight the lines from the solenoid stack to the 5 ports you will see with the key off the 5 port goes to “neutral” and air is blocked in all directions.
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Seems pretty clear the problem is in the 5-port since “up” does function. I’ll check more today.
BTW, Jon, this new website seems to kick me off and make me re-login in the middle of functions.
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Joel, I think that you might find the five port is either not sealing or not moving the spool all the way.
The sitre is timing out and our web guy is checking on that. When we moved to our new server the time out was the default and that has to be corrected.
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Anybody know where the front 5-way valve is located on my type coach? I suspect Liberty has modified the system with the automatic leveling. If I understand the repair manual, the oem location was above a 3-way on the back wall of the under driver bay, but my bus seems to have 2 3-way valves in this location.
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It is hard to see, but it is on the rear bulkhead of the steer compartment. Look beneath the solenoid valve manifold.
Liberty’s changes added the 2 solenoid actuated valves on the floor of the compartment.
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My 98 XLE has one next to the front manual leveling valve. FWIW
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Think I found THEM! My 1999 IFS has TWO, one on each side of the front leveling valve. The leveling valve has an input line from each 5-way that may be connected internally in the leveling valve. I disconnected the lines from each 5-way to the leveling valve and put air in the front bags. One of the 5-ways leaked back toward the leveling valve, the other did not…I assume that’s my leaker.
What I don’t understand is; why 2 valves? The front air bags seem to be interconnected. Unless there is some pressure limiting device of some sort limiting the air transfer from one bag to another on turns, I can’t see why 1 valve wouldn’t do the job. Can someone enlighten me?
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do you have the kneeling feature?
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Joel because I am in the midst of suffering from CRS I am momentarily unable to tell you why there are the two valves, but they came about with the introduction of the IFS. If I remember or get frustrated enough to pull the diagram for my coach I will let you know why it takes two to do what one did previously.
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I looked your coach on prevost web site : that is how it was built as a shell… they both (5 port) hook into the 5 stack (level low) in the steering compartment. peumatic (sp) diagrams put in 45 xl ME then your # x 6872 and it came rite up.. follow the broken lines from the 5 ports to the stack(level low)
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right, but why do we need 2?
I’m both curious and thinking of deleting 1 but….there must be a reason it’s equipped with 2.
Also wondering if the norgren valve # K910026 (which came off) has been changed to a different part #.
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Joel,
Without digging my drawing out, I have two 3 ports, not 5 ports for the front, maybe they changed for the XLII. I’m guessing 2 are needed since there are two functions, the level valve and the manual up/down with level low.
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Joel,
The Norgrens on our coaches are standard valves, but they have been given proprietary part numbers by Norgren for Prevost. If you have a Norgren dealer nearby they need to see the valve and then they can supply new ones with the Norgren number. Or you can buy them from Prevost for a few bucks more.
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