Air Problem 95 Prevost XL

[DKO]

I have been away from the bus and civilization for about two weeks but came back to discover a new problem.

When the bus is running and I am prepairing to level up and park, I flip the lever to lift the tag to set the back of the bus down. Normally the air releases, the tag lifts and the back of the bus lowers.

Now I hear a lot more air when I flip that lever and after the bus sits down the air keeps right on "escaping" and won't stop until I flip the lever back in the proper position for driving.

In that position everything seems to be OK and the level is right when driving and the air pressure remains good when driving or parked.

Any ideas about what has changed, what the problem is or what the solution might be? Am I in danger of losing air while driving?

Thanks in advance....

DKO

[robertglines1]

That lever engages your tag lift cans also. Bad diaphragm or bad air line to one or other.Bob

[robertglines1]

Davey: listen behind tag each side.  If not there  open steering compartment and listen by norgren valve behind level low coils for air.  let me know.  Bob

[DKO]

Bob,
The air seems to be coming out close to the tag on the driver's side. It is much louder than normal.
DKO

[robertglines1]

90 % pancake (rubber) on lifting device on tag axle. Cheap part & not hard fix. Part under$10- Remove tire (tag) and you will have easy access.  Probably a hour maybe 2 shop time at most or and shade tree guy should be able to do with basic tools since you are on road.      On the 98 you don't have to dump tags to level- I'm fairly sure you don't have to dump yours. 99% sure because bags including tag are on same control until tag lift is engaged.     Bob     

[DKO]

Great. Thanks, Bob...

DKO

[DKO]

Bob,

On mine the tags lifts when the air pressure drops. Other models the tag stays in place even if the air leaks down. That was my understanding from Prevost. The later 95's stay up is what they told me. Since my bus is NOT leak free or even close, I go ahead and lift the tag when parking because it will only last 30-45 minutes tops.

IF it's not raining too bad, I plan to crank the bus tomorrow to see if I can spot the leak for certain.

DKO

[robertglines1]

I understand what your saying: It was about then when they changed so if you had no leaks in the suspension side of air system your bus would stay up. The only way out for air was thru the norgren valve located in the steering compartment.(it normally exhaust air when you lower any part of suspension thru level low) Yours can be changed to act that way.  You might be able to buy a replacement assembly for the tag lift Reasonable if you don't want to take your apart. But the pancake would only be around $10.  I have loosened the band and rotated one 30 degrees and it stopped leaking. You know I can't say that out loud!    Bob

[DKO]

I started the bus and checked for the leak today. The rush of air is definitely on the drivers side of the bus. This is a picture of the canister that is hooked to the chain that lifts the tag.



I sprayed it with soapy water and had my wife flip the lever inside and you can see it is leaking some in two places.




However, I could not feel any big rush of air escaping when I had my hand in there. Of course I could not leave my hand in there for long because the bus is coming down. I did try it several times in different places around that canister but I could feel no air with my hand. The canister is obviously leaking some but I do not think it is the main culprit.

Does this mean the air escaping is more likely coming from the norgren valve underneath the bus.

If the valve is exhausting with the tag lift engaged but at no other time I should be OK to drive it, correct?

Do truck shops work on these valves?

Thanks,

DKO

[stevet903]

There's a norgren there to dump the air from the tag axle airbags as well - do you have an air system diagram inside your engine door?  If you don't, do you have your VIN handy and we can see if they have an air diagram on line...
Steve

[DKO]

They told me on the Prevost Community board that there is a norgren valve that I can't get to without getting under the bus. If it fails it will do the same thing that my bus is doing.

DKO

[robertglines1]

it does not do it unless you dump tag .Correct?  don't dump tag.     Yes there is a norgren valve inside frame on drivers side with a tee on top that goes to each tag lift it is actuated when the norgren valve that controls the tag bag is signaled to release air from it.  good chance the can is the only leak if not you will need to be over a pit to check the norgren inside frame between drive and tag both on drivers side. Those are about $200 each.   Bob

[robertglines1]

DKO: On PC web site on top  Articles  about 2/3 way down (not the first one) but by Jon there is a article on trouble shooting problems with level low.  With pictures!  Maybe that will help. I don't think you need to release your tag to level.   Bob

[luvrbus]

DKO, most of  the larger Volvo truck dealers ( Volvo owned) have a section just for Prevost and the Mexican built Volvo buses the one here in Phoenix sells Volvo buses and has 6 bays with a paint dept for buses fwiw nobody else is going to work on the D13 Volvo engine in a bus lol

[stevet903]

Here are the instructions to modify your tags so they don't dump when the air gets low...

http://prevostparts.volvo.com/technicalpublications/pdf/Sb96-14B.pdf