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Ride height adjustment
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The tag logic (dumping air with low aux pressure) was discontinued around 95, so Jerry’s bus should hold with zero aux air.
Jerry, since you did the two 5 ports, your problem is probably down stream from there. They are seperate and not connected, so you’ll have to work at each side individually. If the fittings are tight and no leaks, the only way to find it is by isolating each bag and pressure testing the bag and ping tank. The other problem area is the 3 port above each tag and if they leak internally, you’ll never catch it unless pressure checking the tag bag, line and ping tank. If all those checks turn out good, then you have to go up front to the 3 port. I don’t know how your’s is set set up, mine has a 3 port for each rear 5 port and that’s how Liberty modified the Prevost level low.
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Both sides in the rear dropping simultaneously doesn’t make sense in any context. They are separate and via the 5 port valves they only share the air supply but as Tom points out that is in the front and requires another Norgren to open.
Without looking at a diagram I think the one common point however is the 3 port Norgren that sends a pilot signal to the three port valves between the drive and tag. On my coaches it has been on the passenger side, high on the frame. That valve sends the pilot signal to lift the tag, which causes the two three port valves to dump tag axle air while supplying air to the tag axle lifts. (I think. I am trying to remember the diagram so it is best to verify.)
The good news is if you can hear air that will be the easist problem to diagnose. Just take precautions when you get under the coach.
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Tom, I only replaced 1, 5 way for the starboard side, and 2 of the 3 way. I’ve ordered another 5 way,and 3 more 3 ways.
This H is different, in that all the Norgrens I can find are over the drive/tag axle for both sides, except for 2 three ways in the drivers compartment.
Thinking back, when I installed the valves, I aired the coach up, and the port side came up all they way, and the starboard wasn’t at all. I went back and looked, and I had the 1/4 in lines on each end of the valve reversed. So, I changed them back, and then the coach raised up level. Could I have damaged a valve maybe?
As you can tell, I’m a little lost right now. My next move is to replace the other 5 way valve and the other tag axle 3 way, and see what happens from there.
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this shows why Norgrens are on one side
Valves are here
Everyone that works on his own Bus, needs a collection of fittings
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Jerry, your partly right….
Everyone that owns and works on there own bus needs a collection of this……
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Jerry has that bus been drive outside, I see on dirt on the valves or tubing?
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10-4 on the cash Al!
Greg, the bus has been inside since I’ve owned it. The valves are above the drive/tag tires. There is a plastic shelf that sheilds the road spray off of them, but it is open to the inside, so dust and road film can get to them.
Good news is, you don’t have to get under bus to work on them.
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Well now I know the H is different for sure. Seems like a better place than the XL and XLII’s. I assume all the plumbing functions are the same, just in different locations.
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I think Tom is right about the operating system being the same, but mounting locations may vary.
We are all going to have or already have problems with the leans. It is the nature of the beast. But that is the only constant and all owners have to be very clear on one important point. The level low system which is part of the motorhome (and entertainer) chassis has evolved over the years and what might be true for my coach today is different than my 97 coach, and different than my 87 coach.
Early models (almost every 8V92 coach) had a system logic that required auxiliary air pressure to be maintained. If aux air pressure dropped off, the Norgrens that control tag axle air bags would dump tag axle air bag air pressure causing the coach to lean or drop in the rear. Later model coaches had a different system logic and aux pressure could drop to zero and the entire suspension system would not be affected.
Even later model coaches added individual air tanks at each air bag which added to places that could leak due to rust or corrosion.
To confuse the issue even more, some converters modified the Prevost system to include an automatic leveling feature. Those modifications over ride the Prevost system so the owner has to be able to understand how those changes impact the coach and the ability to keep it level. In some cases the converter added system is working to keep it level even with the key off, so an owner needs to isolate the Prevost system from the converter added system (usually an HWH) to analyze where and if the suspension has leaks.
Liberty adds valves that are controlled by their automatic leveling feature so we cannot even say how many valves a specific coach has unless we know the converter.
My point is answers and analysis of issues can only be treated as general unless the writer is able to identify the comments as specific to a particular coach or converter. That is one reason why I always try to suggest an owner that wishes to do his own repairs to correct the leans should start with the pneumatic diagram specific to his or her particular coach.
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I understand Jon,
I’ll report back when I figure it out. Mine has HWH leveling.
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Just to make it more confusing, the Prevost drawings for your coach will not be accurate if the Converter modified the system. I had to take my Prevost drawing and make changes to account for the modification Liberty did for their auto leveling system. Not a big deal, but you need to be aware of the change and how it effects the Prevost original drawing.
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I think that is the case with mine. Tom, since you understand the internal workings of the Norgren valves. Could I have damaged the 5 port by hooking up the 1/4″ lines on each end backwards? When I aired the bus up, the whole bus leanded hard to the starboard side. When I changed them back, it came up level. But since then, after 4-5 hours, it is sitting down in the back. Front is up and level.
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To over simplify Jerry, the 5 port Norgrens in a neutral position (no air to either end) locks the air in the air bags. It is in the neutral position when the key is off or when your level low selector is in any other position than the drive position, the key is on, but you have not selected up or down. Liberty owners ignore that because you do not have the Prevost level low switch combination.
When you select the drive position on your selector and the key is on, air will go to one of the 5 port actuators on each of the 5 port Norgrens and open a path to the air bags through the ride height valves.
When the key is on and the selector is pointing to any one of the three positions air goes to the opposite 5 port actuator and when you select up or down you either supply aux air pressure or dump air from the air bags.
If you reverse the 1/4″ lines going to a 5 port Norgren you reverse which actuator gets air and makes the coach do things you did not command it to do.
There is no way possible for you to damage any Norgren no matter where or how you hook up the air to or from it at any port. The only thing that gets damaged is you ego because you have to go back and redo the air lines so they are right. Actually almost all work on a Prevost has the potential to bang up our egos a little.
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Good explanation Jon!
Yea, my ego got banged up good when my wife said “I thought you were smarter than that”
I have the Level Low Selector, but I have never been able to get it to raise or lower the coach. When I select anything, all it does is sounds like air is going nowhere. Will not even lower the coach.
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Here is where I lose any ability to help. If you have an HWH you have to find out if that can be turned off so it does not over ride your level low commands.
If you can do that your level low switches should allow you to make the coach go up, down, or into the driving position. The level low rotary switch has 4 positions: Drive, LH rear, RH rear and front. Select any but Drive and the up-down rocker switch will make the bus go up or down at the position slected. If that does not function that way something is interfering with how your level low functions manually and it is possible it is the HWH.
Any HWH leveling system experts able to help here? We will cut your membership dues in half for next year if you can help.
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