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.
99 Volvo VNL64T/610 Motorhome
2001 Alpha Gold 39'10"