Volvo air brakes

[Bill R]

F.Y.I.
My air pressure took forever to get pumped up to less pressure that normal. I found air coming out of the governer (D2 governor from Volvo $17.oo) mounted on top of the compressor. I changed it and no improvement. The old one had brown oily junk in it. Found air coming out of the bottom of the air dryer module purge valve (mounted to frame in truck center). Removed air dryer spin-on canister from top. It was gunked up. O ring at center was broken into pieces. This allowed dirty air to mixe with filtered air. Residue got into purge valve making it leak. Replaced canister (68.00 at Volvo). Got air dryer/air brake manual from www.wabco-auto.com. Volvo has a service kit for this valve $45.00 but I took mine apart and cleaned it. Now I got up to pressure in short time and was even able to adjust the governor to get cut out of 130lbs and cutin of 125lbs. The canister should last 3-4 years, depending on the amount of oil that gets stuck in it. It is a can of dessicant that gets regenerated to dry air again and again....There are two other valves in this dryer assenbly. might do them just to make sure no residue is in them. When I shut off the engine, I think the governor (unloader) unloads the compressor down to 90 lbs. Got to do more checking and reading of the manual that I downloaded. Started this two days ago, so a lot more to learn..... Interesting find: All the air comes from the same compressor, but is functionally divided and isolated by a safety module, sooooo if the air bag breaks the air brake system will be unaffected. That was encouraging....
Anyone have repairs or fixes to share??
My moto is to not pay any one to do what I can do myself and to learn by doing.

http://community.webshots.com/user/onevolvoman
99 Volvo VNL64T/610 Motorhome
2001 Alpha Gold 39'10"

[OLDphoneman]

Hi Bill -- --

Good for you !! Not only on the find of your air leak -- but the learning and repair of the air dryer. The cartridge is rebuildable -- check your receipt to see if you were billed a core charge.

Also -- the parts kit for the valves -- is generic -- and there will be extra parts -- so care is needed during the dis-assembly -- to see whats needed and in what sequence for re-assembly.

This is one reason -- it is imperative -- during the Pre Trip at the start of the day -- to "purge" the Wet Tank. This is the 1st (front of tractor) of 3-air tanks. The way this is done -- open the battery access door -- and in the left corner is a steel lanyard connected to the dump valve of the 1st tank. Give it a couple of pulls -- air excapes -- and as water/oil is heaver than air -- this substance is "blown" out of the Wet Tank.

As the air compressor pumps air -- air is heated -- as it cools it condenses -- it's wet. Oil bypasses the pistons/rings of the compressor -- thats how oil is introduced.

The air then goes from the Wet Tank -- thru the air dryer to be cleaned/dried and stored in the remaining 2 - tanks. It's absolutely imperative that the air be clean and dry in the air system.

Tell you what -- You come to Parker in September -- and I'll tell you what happens if you "over cam" a brake -- And what would you do when you've ruptured the rubber diaphram in a Max-Can .........:^)

I to am learning -- as I've always been a Hired Shoe -- from 1970 .......... Over the years -- I've really driven some pieces of junk !!

By the way -- have you any more pictures to upload ?? ?? ??

Tootles ......

OLDphoneman