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Questions on leaks for air bags
Hello. As usual, I have air leaks, this time on my 97 XL. I did find and fix a couple. However, I still have some leaks in the aux system, and this seems to be affecting at least the rear air bags in a weird way.
If I connect my home air compressor to the aux system, such that it can never drop pressure to 0, the rear bags will hold. If I do not have this supplemental air pressure source, the rear will drop overnight. I thought if you turn off the ignition, then the air bags are all isolated from the rest of the aux system. Does it matter if level low is “on” when turning off the ignition? I assumed it does not.
I have been hearing a leak in the front suspension for a while, and I discovered it is coming from the suspension height valve and a Norgren in the front-driver compartment, even with level-low enabled! This only seems to happen if I air up the front to ~120+ psi, and it only happens exactly 1.5 minutes after operating the level-low to 120 psi on the front (I think the same thing happens on the rear as well). Is there some sort of limiter that kicks in if the pressure in the bags is too high? I did not experience this when limiting the pressure to 110 psi.
Incidentally, even when the pressure in the bags is 110 psi or lower and level-low enabled, that front suspension height valve [only, and not the Norgren] still has a [slower] leak. When in level-low or ignition off, does the height valve still have air pressure from the aux tank? Right now I am assuming this is my primary leak for the aux system.
Anyway, if you have any insight on these issues, feedback is very much appreciated! Thanks
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14 Replies
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Andrew on my bus when the bus is parked and the key is off, the suspension circuits are isolated from the tanks via the Air piloted valves. In other words I can dump all my air down to zero and my bus will still sit at ride height.
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Thanks for the links, I am reading them.
I think the front 5 port 3 way valve is part of the problem. On multiple occasions this valve has opened its exhaust port (#5) and stayed open, even when coach is completely off, literally minutes after absolutely zero activity with the suspension!
When this happens, I have observed at least 2 times that the front air bags empty and the coach drops to bump stops. I am pretty sure this has happened to the rear as well (not at the same time as the front, but not sure if both left and right rear dropped at the same time).
Could this be the level manifold and solenoids instead of the norgren 5-port 3-way?
Since the front just dropped, I am going to air it back up, turn off the ignition, then immediately dump the aux tank to zero. If this norgen randomly deicdes to dump the air and subsequently drop front or rear, then I have to assume the level-low manifold and solenoids are not the problem (this is assuming absence of air pressure signals always leaves the norgren closed) and it is the nogren.
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My mistake, not the 5-port but the 3-port is exhausting, even with aux air at 0psi
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Took the 3-Port apart, looks just fine and spring inside is quite strong. One correction, I am not sure I got all of the aux to 0 psi. When I disconnected this valve to inspect it, pulling port 1 resulted in the tag axle going up. So I guess I have the “old” tag axle control. I am at a total loss why this norgren controls the tag and can dump the front suspension, but I need to study the air diagram some more
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I think you may have a leaky Norgren at the drive air bags. If this valve passes air it will come right out in the steer bay as you are finding.
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I did get under the rear and spray all norgrens and fittings, no obvious leaks.
After looking at “hectors suspension” interactive diagram, toggling between various modes, I can see that the front 2-way does not really control airing down the front or rear, it just controls adding air. It looks like ports 2 and 3 are connected when there is no control pressure applied to port 12. When there is pressure, port 3 is blocked and ports 1 and 2 should be connected, allowing are to flow to 1 of the 3-way norgrens.
I am not even sure if the 3-way valves are to blame. Based on their condition and general cleanliness, it would not surprise me if they all have been replaced in the last 5 years. Every single one has compression fittings instead of the push-to-connect. Someone has definitely been through this stuff before.
I do wonder if what I am observing could happen if the level-low manifold and solenoids has something wonky. For example, if there was a small leak, allowing air pressure from the manifold inlet to go past the front control valve, I think over some time it could pressurize the 3-port front valve and the 2-port further upstream near the bags. A slow pressurization of these valves might explain why I see the air dump 1.5 minutes after I air up the front. Once those two valves are activated it would dump all air from the front bags.
To make things even more complicated, I tested the tag axle with the engine running and the parking brake set, lifting it seemed to go ok, but when trying to extend the tag back down, the left rear dumped all it had in all bags, quite a shock. The only way to get it back up was to raise with level-low. Putting the bus in drive and keeping the level-low in “drive” did not work.
I honestly have no damn clue what is happening. It’s temping to throw money at this an replace everything, but that’s probably very wasteful. If I could just start by finding out why after 1.5 mins the front drops suddenly that would be nice…
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The Norgrenvalves have nothing to do with the Primary and Secondary air tanks they are Only for brakes and E- brake, The aux tank is for leveling system drive mode and level mode door lock and any air devices, If the aux tank drops the Primary and secondary should not be affected,if you look on air schematics there is air check valves on Primary and secondary tanks, You can also see a pressure protection valve PR-2 on the end of the AUX tank, So if your driving down the road and a air bag blows or your air door lock blows your (tell me if i’m wrong on this) you aux drops to 75 psi and you still have full air in Primary and secondary tanks for stopping. The Air Schematics is a great learning tool.
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Art, my primary and secondary tanks are just fine.
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On my 97 Royale there is a 3 port Mac valve on drivers side on inner frame above tag that mine was not good replaced it with a 3 port Norgren also there is a chain on the tag that my swivel bracket has a bushing that turned that has a grease fitting to lube it could not get grease it was froze up caused big problems. I’ve replaced all 3 and 5 port Nogrens like 6 years ago and new diaphragm for lifting tag and up graded the air dryer to a Bendix AD9 dryer everything works well after that. Tag lift
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
I have replaced the front leveling valve and that leak is gone now. I do certainly have other leaks, as the aux psi drops pretty quickly. I have 5 and 3 port valves and a new level low manifold w solenoids on the way to take care on the steering bay. If I still have leaks, I’ll address the rear valves next. BTW the existing leveling valve was not a Haldex.
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Just lost the air bag on the front drivers side of my toad (2014 Jeep GC). $4,000 for parts and labor and that’s just the drivers side. Never dreamed the toad bags would be more than the bus.
Chuck
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I did replace the 3-way and 5-way in the steering bay, but don’t think it made much of a difference. I still need to replace the level low manifold (I have the part). A couple other things:
1) I think the bus is leaning to the left while driving. Perhaps I need to adjust the leveling valve. I do have two more new leveling valves, so I plan to do this on both sides.
2) I don’t know if this is standard behavior, and I don’t ever remember having this happen on my 2001 H3, but excessive use of lifting the tag in a short period of time really depletes the aux air system. It can easily drop below 100 psi, and at one point the suspension was too low to drive. I am at the point where I am a bit paranoid to use the tag. Is this normal? I’m talking about using the tag perhaps 3 times in 2 minutes. In these situations, should I just leave the tag lifted until I know I am done with tight turns?
Unfortunately I have not been able to spend any time on the bus or on this forum lately. We bought a 170 year old house in Seguin, TX, and moved from Austin. I’ve been a bit busy with the house, and it’s also been DAMN HOT this summer. I am hoping the house things settle down soon, and I can spend some time on the bus this Fall. We have a trip to Huntington Beach, CA planned for Christmas, so I really want to be ready. I am contemplating taking the bus to Prevost Houston should I not be able to or not have time to resolve these pnumatic issues.
Oh, and one of the roof top A/Cs went out! Hopefully in about 6 weeks I can give yall a review of a inverter-based roof top heat pump
One thing I am looking foward to: Once we are certain we are staying in Seguin (my wife told me she needs six months), I am having a bus barn built!
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See Below:
1) I think the bus is leaning to the left while driving. Perhaps I need to adjust the leveling valve. I do have two more new leveling valves, so I plan to do this on both sides.
This might be a problem, your manual should have the height and where to check it.
2) I don’t know if this is standard behavior, and I don’t ever remember having this happen on my 2001 H3, but excessive use of lifting the tag in a short period of time really depletes the aux air system. It can easily drop below 100 psi, and at one point the suspension was too low to drive. I am at the point where I am a bit paranoid to use the tag. Is this normal? I’m talking about using the tag perhaps 3 times in 2 minutes. In these situations, should I just leave the tag lifted until I know I am done with tight turns?
I think you might be over using the tag lift? I have used my tag lift maybe once in the past 3 years, and don’t even know why i used it that one time. Maybe on a 45 footer it might be more important, not on a 40 footer. Why do you feel the need to use the tag lift so often the compressor can’t keep up? One thing you can check is run the air up to 120 psi, leave the level low in drive mode, turn off the key and go back to see if you have any air leaks. maybe you have a leak in your tag circuit.
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