not holding air

[eddiepotts]

On my 82 Prevost I lost air this weekend. I could only hold about 30#. I found what I think is the a brake canister and had air blowing out tho bottom. I took the nozzle off of it and seen a bolt in the middle. I turned it a couple of time and got pressure back. But to loose it 10hrs later. So now what is the fix. Is there an O-ring or something to replace or is there something else that causes air to come out there. I am glad it happend only because I found some loose bolts on the driveshaft with one missing. So what I hope is a little problem here it might have saved me some big problems. Any advise or drawings of what is there would be helpfull. Thanks

[bobofthenorth]

Any chance of some pictures Eddie?  Maybe somebody else can tell from your description what you are looking at but I can't.

[robertglines1]

if you go to the prevost web site they have tech diagram online for pneumatic system...last letter in your serial number plus last 4 digits....sounds like a pressire control valve not a brake canister   both are rebuildable...

[wildbob24]

,

[eddiepotts]

This is next to right rear wheels inside the frame. It is tall with air lines going to what looks to me like air actuators for the brakes. The nozzle was just a tin cover that had 3 little Phillips head screws. it blows strait to the ground. The bolt that was exposed was holding a part that may be a piston or valve. Depending on where I turned it it would blow harder or less. My last fix was when I pushed up on it. I hate not knowing what it is but I will try to get some pics of it when I get home. I just did not want to turn it much in case there was a setting. It may even need to be tight and that's why it is blowing. I did make several rounds but it did not feel like it was getting tight.

[DaveG]

Sounds like an exhaust port cover to something.

[robertglines1]

air dryer...about 6 inch diameter and about 16 inches tall...should not leak out bottom except to exhaust moisture on occasion .usually when the compressor reaches 120 lbs..between tag and drive on passanger side..prob take apart and clean replacing filter...should have a pressure relief valve on side also...

[eddiepotts]

Robert, that's it. is there a gasket kit I need to buy before taking it apart. or is it something that will just bolt back together. If anyone has a drawing of this I would greatly appreciate it. I have a run coming up in two weeks and I have to know I am good.

[robertglines1]

sent you pm with my phone number

[bevans6]

When I come up against things like that, maybe original to the bus, old, generally worn out, I tend to try to see if I can replace with current new stuff rather than rebuilding the old.  New air dryers aren't all that expensive, may be a way to go in this case.

Brian

[stevet903]

I think you have an AD-2 air dryer.  Here's the manual for it:

http://www.bendixvrc.com/itemDisplay.asp?documentID=3604

Look on page 12 for a picture of the end cover - is this what you are talking about?  If so, you can get a reman cover for $93 at Napa, probably much less at Fleetpride or your local truck parts store...  You most likely have a 24V heater in it, so check that before you go.

Steve

[eddiepotts]

Steve, This is what I needed. The bolt I was turning holds the purge valve. It should be torqued to 50 inch pounds. Mine is loose. fist thing is try to tighten it and see what happens. I bet the valve is off it's seat and just blowing. I got pressure when I pushed up on it but never got it to stop completely.

[niles500]

I'm with steve - sounds like an AD-2 air dryer - purge valve replacemant/rebuilds can be found for less than $10 on E*** - HTH

[robertglines1]

You could have a Rockwell Wabco #RWABK-095..System Saver 1000..Prevost tech manual on line(prevost car website)under parts and service...use your last letter in serial # plus last 4 numbers(unit number) or just skip the enter part (year model etc)and hit search and it will give you a list of all wiring and pneumatic diagrams available...or try unit K-747 in unit box...Prevost parts Charlie....1 800 621 5519...on line manuals you can copy available there also....shop parts prices,lots of times they are less expensive including freight and no tax..

[eddiepotts]

Tightening was not the answer. I can turn it forever. What I need to know now is this something I need to remove from the bus or can I rebuild it in place. It is the Bendix ad-2.