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Thread: 1995/94 Prevost Liberty Level Low Problem.

  1. #1
    Join Date
    Feb 2018
    Location
    Belmar
    Posts
    8

    Default 1995/94 Prevost Liberty Level Low Problem.

    I am new to Prevost and just made the dive about a month ago and purchased my first bus! I am living it in currently and at the same time updating the interior and fixing odds and ends. The problem I am having started with me waking up with the bus leaning to the right and basically falling into the side of the coach when I got out of bed. I would lower the left side to compensate and then it would be fine. Well now I moved spots and I can get the the right rear to air up with level low manual mode on but can not get it to go down. I checked the the second solenoid from the bottom up. It's getting power. I took it off the post and powered it up and could get a small release of air when when I slid it back on the post. I reviewed Jon Wehrenberg's tutorial on the level low system and believe my system is slightly different in that it uses a 5 port Norgren on top of a 3 port Norgren, with the exhaust port plugged in the starboard side and the port side is connected. Then mounted to the floor is 2 three port valves which I believe to be responsible for exhausting air to lower. The port side lowers and raises without a hitch and when lowering exhausted air is released from the port 3 port Norgren mounted to the floor. When the starboard rear is lowered the starboard 3 port is energized but no air is exhausted. Does anyone have any idea's? I have a funny feeling the 5 port in the rear by the drive axle may be hanging up between exhaust and ride height control.

    Jon Wehrenberg, your tutorial on level low was a huge help and really helped clarify the system, Thank you!!

    Mark

  2. #2
    Join Date
    May 2012
    Location
    Beverly Hills
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    2,377

    Default

    For whatever reason, Liberty modified the Prevost Level Low for their leveling controls. It may not be on your coach, but it sounds like it.

    Raise your tag axle and relevel the coach. This will help isolate the problem. Typical causes of the lens are push-in fittings, Norgren air control valves, and air bags.

    It would be unusual for a Norgren valve to get stuck. They are not much more than a moving plunger sealed with o-rings. The o-rings would have had to freeze. The electric ones typically fail because the energizing coil is inoperative. Warning, Liberty control coils are 12V while all Prevost coils are 24V.

    Hopefully Joe Camper chimes in. No one is better at isolating and repairing anything that's under the coach (as well as other systems).


    Gil and Durlene
    2003 H-3 Hoffman Conversion

  3. #3
    Join Date
    Mar 2013
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    Chicago
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    You got two different things going on two different problems but with a common factor, the left rear.

    First Liberty added those two additional three position norgren on the floor in the steering bay so that you can control all three corners at the same time with the rocker switches by your left forearm by the driver's window. That's not how Prevo sends that bus out of the factory level low.

    You can only do one corner at a time with the factory system and you don't have those three separate rocker switches like you have in that bus that's all a Liberty only thing. I know there's a bunch of non Liberty folks out there that are quite unfamiliar with this. It ud be nice if somebody with a liberty could take a picture of the level low controls so that those without Liberty can see what we're talking about here. Maybe somebody can take a picture of the 4 position switch that Prevo uses for factory level low so Mark and take a look at that since he's a new Liberty guy and he can see what the factory stuff looks like and how different his is.

    The existing three position norgren on the back wall of the steering Bay on a liberty that's controling front only now, and the two that they mounted to the floor that's left rear and right rear. I'm not sure which is which on the floor I'm assuming there left and right for left and right but I'm not sure how they're mounted on the floor forward and rearward, don't know.

    The fact that it won't go down in level low is either electrical or the norgren Air manifold or it could be one of those norgrens up in the bay under the driver on the floor. By virtue of the fact that you can raise that corner in level low but it won't go down tells me that the three position spool at the left rear corner is not the culprit, it's in the steering Bay. Could also be something as simple as the rocker switch for the right rear at the panel by the driver.

    The lean you have IS a result of something leaking at the right rear corner itself, either one of three airbags or one of two spool valves.

    Gills little trick to speeding the diagnosis of a lean in the rear I would add something to it. Put it in level low left and right rear and FIRST go all the way up with the left and right rear THEN raise the tag . This will leave the drive axle at a higher level with more air pressure and sitting higher than if you try to raise it up after you lift the tag. If this gets it to stop dropping and the bus doesn't lean after you've raised the tag your leak is in your tag bag or your 2 position spool. If the lean still remains it's one of your 2 drive bags or the three position spool.

    Norgren gets stuck sometimes but almost never the norgren's in the steering Bay. Usually if they do stick they'll be the ones that are exposed to the elements at the suspension corner itself.

    I'm less than a week away from a trip to N.J. Mark.
    Last edited by Joe Camper; 05-17-2018 at 02:04 PM.
    1990 Peterbuilt 377
    3406 B Caterpillar
    9 Speed Roadranger
    708 243 7871

  4. #4
    Join Date
    Feb 2018
    Location
    Belmar
    Posts
    8

    Default

    Thank you both Joe Camper and GIl_J for the helpful responses! This morning I put all air bags to full up position in man mode. I then lifted tag and right rear (problem side) dropped immediatly.

    Joe where in NJ are you going? I am in Bonita Springs fl for the next month.

    -Mark

  5. #5
    Join Date
    Feb 2018
    Location
    Belmar
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    I have to go get a couple 20 ton jacks so I can jack the chassis up and take a look at the rear air connections.

  6. #6
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    Mar 2013
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    Chicago
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    You better be careful with those jacks I wouldn't suggest doing that until you're really really sure somebody shows you the right way.

    I'm going to be visiting my brother in Jersey this week but for the next 12 weeks I'll be working on a farm in Orange County, upstate New York. Middletown would be the closest Big City where I-84 and NY17 intersect.

    So the bus goes down slower to the right with the tag down but when you lift the tag it goes down real quick? Well isn't that quaint.

    I'll be there till the first week of August or so.
    1990 Peterbuilt 377
    3406 B Caterpillar
    9 Speed Roadranger
    708 243 7871

  7. #7
    Join Date
    Feb 2018
    Location
    Belmar
    Posts
    8

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    Joe Camper,
    Ok you're right the problem with the right rear not exhausting the the air was due to the electronically controlled Norgren valve that controls feed and exhaust ( Liberty added). But in my investigation I took off the Light near the drive axle on the right side to gain access to the ride height control. I removed the bolt holding the push rod to the carriage assembly and moved the are slowly in either direction while the bus was in road mode. Is this valve have a delay?
    -Mark

  8. #8
    Join Date
    Feb 2018
    Location
    Belmar
    Posts
    8

    Default

    PS, I didn't jack up bus yet but was going to jack from the chassis points located directly behind tag axle, I was then going to build cribbing from wood. Maybe over kill but my objective was to keep the wheels on the ground but the frame raised. Come to think of it I maybe better off doing like someone I saw I believe on this forum who staggered plywood and laminated to make a ramp. Pretty cleaver idea I though. That way may be better because then the systems could be tested.

    My family was from the Middletown area, Middletown NJ we're talking right? My stomping ground is Belmar.

  9. #9
    Join Date
    Mar 2013
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    Chicago
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    Yes there is a delay in the ride height valve that you took the linkage off of. The ride height valve if it goes bad it cannot make you lean, with the key off, EVER.

    You said as soon as you raise the tag the right rear dropped immediately. That's a new one. That can only be the two position norgren failing if that's occurring on the right rear and that may or may not be what's causing you to lean with the tag DOWN. It probably is but that's not to say there isn't something else on that corner leaking down too.

    Just thinking out loud here, with tag up you've created a real quick leak a dramatic leak, that's not what you were experiencing with the previous leak it was a lot slower overtime, overnight. That 2-position spool that's leaking dramatically with the tag up when it's in its other position it may or may not leak in that other position. Could be completely airtight when it's in the other position and you could have somethig else slowly leaking too.

    You really don't need to Jack the bus up at all. Just raise it all the way up in level low and then get a jack stand that just fits under the support point that you're describing.

    Do not support the bus with Jack's support the bus with stands.

    If you use ramps 2 things about ramps they're very very heavy and cumbersome and you have to make them long enough so that the tag is on the ramp with the drive tires and if you don't you can hyperextend the tag axle.

    If you want to call me I'll be happy to take the time to guide you through learning a few things about supporting your bus and getting it up and getting under it for the first time I wouldn't mind at all.

    If you're not sure or you don't have any service records on that bus you might want to go ahead and just do the whole RR corner all five components are approximately $900.

    Middtown NY. Bullville is specifically where I hang in upstate. That's a tic south of Pine Bush.
    Last edited by Joe Camper; 05-17-2018 at 11:13 AM.
    1990 Peterbuilt 377
    3406 B Caterpillar
    9 Speed Roadranger
    708 243 7871

  10. #10
    Join Date
    Mar 2013
    Location
    Chicago
    Posts
    1,919

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    Mark if you go to the category bus washing and waxing and open that and then go to the thread undercarriage cleaning and care, towards the end of that thread I got a bunch of pretty good pictures and an explanation on how you can put the bus up and support it safely and get it high enough so you can scoot around under there like I do.

    Never set a jack or support stand on ground that you are unfamiliar with or unaware of its base.
    1990 Peterbuilt 377
    3406 B Caterpillar
    9 Speed Roadranger
    708 243 7871

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