-
Ride height major malfucntion HELP Please!
Greetings from Lubbock –
So I’ve owned and opererated my Prevost for the last 3 years. It is an “orphan coach” Made by AMERICAN INC out of Alan Mich. It has a front kneeling and low level system right left and front.
I have driven it 15000 miles without major problems.
Prevost Houston put new brakes – the whole system, new shocks, all new bags front/drive/tag
new tires front/drive/tag
It is a 1995 Prevost with a detroit series 60 first year model with an allison 6 speed.
When I light up the coach and turn up the rpms, it normally fills to ride height in about 2 minutes.
Well…
I am on my way north out of austin, texas and stopped for the night at a park in lubbock. The park is a little squirrelly, so when coming in to the park I flipped the tag axle switch to dump the air for cornering purposes. The speed bumps were epic, and I didnt think much about going over them with my tags up.
The next morning I air the bus up to head out to colorado. The bus airs up front and rear right full as can be but nothing on the left side – flat sitting on its frame.
I flip the tag switch and dump the air to re-engage the tag hoping to jiggle something loose. No luck.
I dump the tag and raise the front up and down both sides come to full ride height and down. no luck
Do a full air up with left leans-o-plenty, then drain all the air in the system, and then repeat five times to try and get any selonoids to trip.
No luck.
I’ve checked the norgren relays under the drivers seat – all are working properly.
I hobbled over to the diesel mechanics in lubbock about five miles away leaning over and looking pathetic.
Being saturday they only had four hours to work on it. Mechanic couldnt locate any leaking on the bags. (they are less then a year old- but they arent filling with air so how would he see a leak anyhow?) The rear norgren 3 valve appears to have air flow.
they are closed until monday, and so I hobbled back to the RV park where I must wait. But I’m so frustrated, I cant even sleep and am typing this on my phone.
Anyone have a quick fix for something like this??? I have some tools, but I’m not at my house, and I don’t necessarily want to spend a huge amount of time with the mechanic hunting and pecking, if I can point him in the right direction on Monday.
Help!!!??Thanks in advance. Really appreciate any and all thoughts.
-
34 Replies
-
More info is required to try and figure out what the problem is. What are the symptoms?
You should at least add the year and converter to your profile.
Most converters have the ride height controled by the center coil on the five port manifold in the compartment
under the drivers seat.
If the center coil is bad, you can swap it with one of the others, if the voltage is the same.
Go to the articles section and read Jon’s article “Prevost Leveling System Diagnosis”
-
Thanks for your response. And apologies for not giving enough information. It’s been a day!
The main symptom is the rear driver’s side won’t air up at all. No air in or out. No leaking sounds. Front airs up; right airs up; left does nothing.
It’s an 1995 American Inc Country Coach. XL40. Actually owned it two years, not three.
I’ve been using the Prevost Leveling System Diagnosis Document dated 2-2-12 to troubleshoot, so I already checked the center coil. It reads at 110 ohms and is filling the front and rear right up and down. The rear driver’s side will not inflate. Just hanging there.
It seems like something could be failing with the left hand tag axle valve? Is that something you’ve heard of?
Also, when draining the systems completely, notice no water out of the front, or rear resevoirs, only a little bit of water out of the rear spit valve.
Is it possible the speed bump popped the basically new bag?
Any other thoughts you might have would be appreciated.
Thanks.
-
Just a shot in the dark. Could it be the left rear leveleing valve? Maybe the linkage has come loose or the valave has failed? It is most likely something else, but that is all I can think of off the top of my head.
-
Funny enough, that was the first thing I checked – pulled off the rear docking lights that American installed and no leaks there. Linkage seems intact. Rubber seems good.
I also read the longer discussion thread in the “pneumatic” section where the problem was solved with the over-pressure regulator. The main difference I see in my issue is that the rear passenger side fills up just fine.
All shots in the dark are welcome – thank you!
-
Cheeeef
I had a simular problem after a “tight” turn over curbing and the rear airbag lost all air and would not re-inflate.
The problem was the “RIde Height” linkage had pushed up past “Center” and stayed in that position.
This dumped all the air in that bag , the fix was to remove the end of the linkage , pull it down past center and reconnect the linkage. This allowed air to inflate the air bag.
Hopefully yours will be this simple.
Bill (97Bustur)
1999 XLV X-6872, liberty #440 -
Can you fill the left rear (?) manually when in ‘level low’?
1999 XLV X-6872, liberty #440 -
Joel asked the right question in my opinion, and Bill had the same idea I had after reading the posts.
I know there is a lot of disagreement with my posture to NEVER lift the tag unless I am in a critical position that demands every fraction of an inch improvement in my turn radius but a lot of people do that. My problem with that being done routinely is I don’t think drivers understand fully what is happening. When the tag lift is employed the number of air bags supporting the rear of the coach shifts immediately from 6 to 4. That 33% loss of lift is going to require a substantial increase in air pressure in the remaining bags to even begin to raise the rear back to drive height. The air bags may not ever be able to carry the 30,000 pounds but allowing substantial time for them to get as much pressure as possible to try to support the weight helps.
But the speed bump comment got my attention. With the tag axle raised and likely the coach virtually sitting on the bump stops inside the air bags it is possible the ride height arm was pushed past the point at which it would allow air to re-enter the rear air bags when the level low was placed in the driving position. Not a good choice to have a coach with the suspension in the lowest position drving over anything that can damage the bottom, like a speed bump. In this case it may not have damaged anything but it might have moved the ride height arm past the point where it will allow air to re-enter the rear air bags.
That vintage coach had time delay Haldex ride height valves and be aware if you plan to access the arm and try to move it manually that you understand there is going to be a short period of time between when you move the arm and air flows.
That makes Joel’s question the key to what I think will fix the issue.
-
I agree, if you can raise the right rear using level low, that points to the right leveling valve being out of whack.
-
I had a leveling valve rod flip once. Took rod off and operated by hand–reattached rod and life is good. don’t run without returning function.
-
MAKE SURE TO BLOCK THE BUS UP while you are doing this ! I had the same problem , mine was the airbag had to replace it ! once you have the bus blocked you can disconnect the linkage and move it by hand and see if you have air at the valve if not need to move up stream to one of the N valves ! but block the bus please !
-
Hi
I live near Lubbock, call me and perhaps I can direct you to a good shop.
Glenn Williamson
806-828-4138
-
Ok – First off – thanks everyone for all of the information. I’ve been working all morning testing your theories and want to give an update. I’m also including photos to give you a visual aid.
Here are photos of the process. Please take a look and let me know if I’m checking it out correctly since it seems that the valve is working based on what I’ve done so far.
Here are the ride height valves:
right valve before air:
Right rear ride height valve closed once the right side is aired up.
Left side ride height air valve before air, same after air
Bus with the leans (you’ll have to lean to view since it only wants to upload sideways for some reason)
Next step, remove the left side ride height linkage. (Yes, bus is definitely blocked!)
linkage disconnected and valve in closed postion.
Manually opening the left rear ride height valve holding until air flows
Removing rear bag air line to check for air flowing
Air is flowing correctly out of the valve.
Air stops flowing when the valve is closed.
Hook it all back up and still no rear bag inflatiion.
So, if I did everything right, I guess it must be the bags unless there are more valves beyond this point in the system? Or possibly a tag axle valve or selonoid that i am missing? When I went over the speed bump with the tag dumped, it did feel like something blew, but I just cant imagine that happening with these two drive bags being less then a year old and very little wear on them maybe four thousand miles?! And I cannot hear any leaking anywhere? Although it’s hard to hear anything subsatantial with diesel running trying to air them up. I think I can safely rule out the ride height valve being the culprit unless Im missing something?
If it is a popped bag, any idea how could I tell if it was?
The guy at McWhorters in Lubbock jacked it up and checked the tag axle bag for leaks, but is it possible that the other bags are popped? (Glenn – McWhorters seems to work on a variety of big rigs, but if you know of someone with a sweet spot for prevosts, please let me know.)
This is definitely the last time I dump my tags unless I’m stuck in an underground alley in downtown dallas.
Thanks for all of the help and advice – any other suggestions are greatly appreciated.
-
Tom –
I posted a longer response further down the line, but I wanted to double check on your post. I can raise the right, but not the left. It’s the left rear/driver’s side that won’t air up. Are you saying the operation of the right side is having an impact on the left? Or did you mean to reference left?
Just making sure I’m not ignoring something.
Thank you!
-
Cheeeeef
In your 7th picture down that is the bolt and nut you want to remove from the end of the ride height lever.
The lever is attached to the rod going down to the axle.
Once the lever is free, if it doesnt raise or lower the bags the ride height valve is shot.
Later
bv
On an edit what Truk said was if you can use your level low to raise the side that is down maually with the switch inside, your ride height valve is bad.
-
cheeeef
Seems that if you had a popped/leaking bag you would be able to hear the air escapeing when you manually moved the ride height valve. American equipment and trailer is an alternate 3707 MLK blvd, 806-747-2991, Kelly Tooley svc manager. What campground are you in. call me if you would like
Log in to reply.