Airpack Teardown

I finally gathered the courage to work on my malfunctioning airpack. Upon opening the air cannister side I discovered a lot of brake fluid. The airpack looks to have been replaced somewhat recently along with the master cylinder. I have had the truck for three years so it would predate that at least, anyway instead of the grimy contaminated conditions I was expecting the cylinder looks clean and new except for the brake fluid. Of all the past threads on airpacks I do not recall anyone discovering this condition, which seal would have to fail for this to happen? On a side note Saturn is out of the rebuild kits and all of the other usual suspects want from $62- $150 for just the kit. Is there another" forum friendly" supplier out there?

You may not need a rebuild kit. Carefully take the airpak apart, claen all parts and reassemble.
There is a u-cup seal in the slave cylinder that can cause the leak into the air cylinder. It's important that the u-cup seals are installed correctly, with the "open" end facing the high pressure. Be careful not to kink the long spring inside the slave cylinder.

Gentlemen, not trying to hijack, but I have a few questions regarding this brake system also... Mind if I bring them up here, or would you rather I start a new thread on it?

peace
Dave

Bring up some more ?'s here.
Cranetruck- once again you are a fountain of knowledge ! I have rebuilt the airpack on mine-Check w/ white owl...I believe they have the rebuild kits very reasonable. The cup on mine had some surface corrosion and once I brake honed the little(high pressure) side and cleaned the cup w/ crocus cloth it worked wonderfully again.

Doc

Okay... asking here...
From what I gather, these trucks use what I would call 'air-over-hydraulic' brakes.

As In... Air pressure from a normal (or nearly normal) treadle valve modulates a hydraulic 'master' cylinder, which then operates the wheel brakes.

The Volvo-on-5-tons project truck uses air-over-hydraulics, and the air side of both units are very rusted, and leak air when the brakes are applied. These Volvo (WABCO - Westinghouse Air Brake Co) units have (guessing) an air tank around the outside of the operating cylinders. It appears to me that we could simply rout the air around the old reservoirs, using additional air tanks in place of them, and simply feed the center port of the units on the truck.

HOWEVER, if indeed the Dueces use an air-over-hydraulic system, I would prefer to simply switch the truck over to use Deuce units.

Any info / knowledge appreciated.

peace
Dave

For the rebuild kits try Ebay seller KCGONZO. I bought one off him for around $20.

Completed the teardown last night. The only thing obvious was the absence of the "o" ring between the air cannister and the valve body, although the gasket was there. All the other seals/ cups appear to be in good shape and in the proper sequence. The bores of the valve body also appear quite good so I guess I am asking if that one o-ring could allow brake fluid to enter the air cannister?
Thanks Again,
Don

Dave,
They are air over hydraulic and conversion should be very simple. No treadle valve involved, just a hydraulic master, the air boost is proportional to the applied master pressure.

I have seen the air-pak pick up a little fluid in the air side on lots of trucks over the years. They thoughtfully added a drain plug for us. Let the system get about 20 PSI, shut it down and pull the plug. Any liquid will get out in a hurry. I wouldn't worrk about a rebuild, and when one fails you can't get any boost at all.

dg