Need help with airpack before this weekend

[Rattlehead]

Getting the truck ready for a trail ride, planned to leave Friday. Brake fluid was slightly down since I checked it sometime last year (has been sitting for months), but brakes were fine. Topped it off, drove it around last night, drove it to work and back today, no problems, will lock up the tires. Seems to have a pinch of air in the lines, as if it sits for awhile the pedal isnt as firm on the first apply as is the second, though it still will stop the truck no problems.

Decided to do a quick brake bleeding today, got a nice looking soldierette #2 (g/f) to help me. Bled the airpack, 3 of the rear axles, then on the last rear axle end the thing sprayed brake fluid out the air exhaust in the downdraft tube. Truck was not running, I hooked the air system up to my compressor so we could hear each other. Air system was at about 85 psi. Scratched my head, tried it again, seemed to work ok and then it sprayed again. Pedal has been hard the entire process, and tons of fluid out of each bleeder. Do I need a new airpack? Why is it intermittent? I did pull the lubrication plug in the back of the airpack, and no brake fluid came out or anything.

It does not do this every time. In fact, I then tried applying/releasing the brake countless times after this, without opening bleeders, and no problems. Now I am wondering if I just let too much fluid out / too fast when opening a bleeder, and somehow caused something to happen in the airpack? I have never had one apart, but am envisioning a control valve/diaphram bottoming out beyond its normal travel, or something to that effect? It did seem that it only sprayed when I got aggressive in opening the bleeder a lot and letting the fluid fly. What is going on?

 

[WillWagner]

NOpe, time to re-build the air pak. Saturn surplus has the kits. Some of the paper gaskets are hard, soak yhem in HOT water. Takes about 1-1 1/2 hours to do, just did mind, pretty easy., You can still drive it, byt I wouldn't reccomend it, you'll go through a master cytl. full of fluid real quick, then NO Brakes!

 

[cranetruck]

The vents from the airpak, master cylinder and fuel tank all join and end in the crankcase breather tube on early deuces. Later the fuel tank vent was separated, but you still have the MC and airpak running together.
The "vent" from the airpak is actually the exhaust from the large cylinder on the airpak when the brake pedal is released. It produces a burst of air ( I separated my airpak exhaust completely and can easily hear it when brakes are released).
I can imagine that if the MC is filled to the brim and the airpak is venting a sucktion taking place, which would take some brake fluid out along with the air.
I'm not saying that you won't need a rebuild, but check your vent lines anyhow.
It's also possible to get the airpak back in good working order just by taking it apart, cleaning and reassembling it without getting a rebuild kit.
The airpak likes to be excercised.

 

[Rattlehead]

Well I had the vent line disconnected from the MC while I was bleeding the brakes, so it must be coming from the airpack. I was just wondering if, while under full air pressure, if you opened the bleeder fully while someone was pressing hard on the brakes, if you could cause a seal to temporarily unseat.

That air line separation is interesting, I wonder what the purpose was behind this upgrade? Could be to keep engine oil vapors out of the vent system for the brakes, which could work their way back to the airpack or master cylinder? Or maybe just to give you a better warning if you have an airpack passing fluid? Seeing wet residue in and below the downdraft tube would not raise any suspicion, but seeing fluid drip from an otherwise dry vent, would bring attention to the problem.

 

[cranetruck]

Read about it here:
http://www.steelsoldiers.com/module...ile=index&name=gallery&include=view_photo.php