Air bags will not releasw air

[rip]

I have an 85 Prevost and had to bring it to a truck shop in Rapid City to have a bracket welded that holds the rear control arm on one of the air bags. After adjusting all the air bags and driving it,we found the two rear valves are not releasing air. The valves were replaced about five years ago and  I would thing both would not go out at the same. I left the shop last night and they don,t have a clue of what's going on.There is no bus shop here and it is obvious they don't work on many buses. I am headed to Mpls. next week but I would like to fix it before I leave. Any thought to why those valves are not releasing air.
   Thanks
   Don

[Slow Rider]

Bump........

[Chuck Newman]

RIP,

I don't know about the Prevost, but my 102A3 air to the drive bags comes directly off the dry tank, through a height control valve (HCV), one one each side, and into four bags.  If I had your problem I would be looking at binding HCV arms (they are adjustable), and/or defective HCVs. 

What happened just prior to this problem?  Is it the same on both sides?  Anyone work around the drive axle lately?  FWIW.

Chuck

[Chuck Newman]

RIP,

After rereading your post, I'm confused in you say the bags are not releasing.  Then you go on to say you don't feel they should fail at the same time.  If the bag fails as in cracks and/or holes, it will not hold air.  At least in the MCI's air bags don't "release" air per say, they just hold air.  Air into bag/out of bag is controlled by the HCV.

If the Prevost has HCVs like the MCI, beg the use of a shop,s run up ramps on the drive axle.  I is only one nut and bolt to disconnect the HCV control arm and manually adjust the bag pressure up and down.  If they go up but not down, you have one or more defective valves.  But I feel there is more to this than we know at this point.

[Busted Knuckle]

Don call Travis Ladson (not sure on the last name spelling) he is in Spearfish, SD he is the owner of Dakotabus/Dakota Trailways! They have a full service bus shop there! Tell him Bryce from TN told ya to call!

Tel: (605) 642-2353

if that don't get him let me know I'll call him myself on his cell #! (he's gonna refer ya to his shop foreman anyway!)
 BK  

[John316]

Are you saying that you can't kneel? Maybe you are referring to the fact that you can't dump your tags to turn...?

God bless,

John

[rip]

T

[rip]

Now my computer is acting up. I went to spell check and it posted one letter,go figure. This problem started after the arm that connects to the leveling arm broke and was replaced by me. I called Provost service center and they stated the exhaust port on both valves must be plugged and the only way that can happen is the accessory tank became contaminated.I drained the tank a few weeks ago and just a little fluid came out. Other than draining the tank,how would can you tell if the tank is clean. I guess I will have to replace both valves to see if that does the trick. All the air bags are new so they are not the problem.I just do not how a tank can become contaminated or how to clean it.
   Thanks, Don

[Busted Knuckle]

Call Travis and ask him if  you can talk to Delbert in the shop! I can assure you that Delbert can get it going!
  BK 

[Sojourner]

Whenever air-leveler's exhaust is not letting out air when needed or plugged it will keep adding air each time it hit a bump to cause air-bag to top-out limited. In other words, impossible drive it downs the road without bus jumping or dangerously skipping on pavement. Is this what you mean or it something else other then this?

Sojourn for Christ, Gerald

[rip]

Yes,that is exactly what is happening.But why would both valves go out at the same time? If my accessory air tank is contaminated will just running a lot of air through it will clean it out.
   Don

[John316]

Just go ahead and replace both leveling valves. They probably needed it anyways. You won't hurt anything, and it is good preventative maintenance too. You are probably looking at two hundred bucks for both valves.

God bless,

John