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Need help with level-low diagnostics
from one of you pneumatic experts. Couldn’t get the link to Hector’s tutorial to work.
I have a 1999 XLV chassis with IFS and the Liberty mods for auto leveling which I don’t use. With suspension locked manually in level low, air is being exhausted from the front ride height valve exhaust and the front goes down. I believe all other functions are normal although I would have to do some reassembly of leaky fittings I’m replacing and take it off the jackstands to be sure it’s not losing air from the same place in normal drive mode. Everything goes up and down fine. I suspect it may be one of the two three port norgren’s adjacent to the ride height valve or the three or five port norgren’s in the strg compt but I don’t fully understand the system. Don’t necessarily want to replace all four valves but if I can figure out which is bad, I’d probably change the two underneath or the two in the strg compt since I’m in there. Anybody know where my problem lies or can anyone give me some further diagnostic procedures?
1999 XLV X-6872, liberty #440 -
6 Replies
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Joel, in manual mode the air should not be going to the ride height valve at all. All air to or from the front air bags should completely bypass the ride height valve.
I would suggest you pull up the pneumatic diagram on the Prevost site. What Liberty has done has no impact on the routing of air lines and only actuates the valves in the five valve manifold to accomplish what you need. That means the diagram will help you trace which Norgen valve is likely not shifting as required to keep the ride height valve out of the path.
When IFS came in Prevost had several variations of the system including the elimination of the 5 port valve in the front and adding an additional three port in the front so I cannot be specific on your set up.
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Thanks, just finished a search and found a thread with the same problem in 2014 posted by ME! Interesting. I think I’ll check my records and see what I did at that time but it sounds like the five port in the strg bay is bad, maybe again. If that’s the case, I suppose I should check for moisture issues, too.
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Moisture will screw up the air system in ways we cannot imagine. If you have moisture getting into the Norgren valves for example you can have problems such as hydraulic lock to sludge filled valve bodies.
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If the coach is on jack stands and it’s coming out ride hieght valve it could be it thinks it’s got enough air so take out jack stands and try it , it maybe nothing and all will work right when on the ground
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the front norgren needs a signal from the stack to operate in exhaust mode. Are you sure it is not getting signal? to do that.??? stuck valve on stack/bad valve on stack. Try spraying the stack with soapy water. don’t remember which cube/valve controls front. will check if needed. Bob
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Top two control the front and air supply, middle is for road height, bottom two are the rears.
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