Brake Fluid Flowing out Vent Tube

[Junglemist]

I posted this elsewhere but didn't want hijack anyone's thread

I rebuilt the air pack, master cylinder, and all wheel cylinders on my M35A2. I also added a fluid reservoir under the hood. I am changing to DOT 3 since DOT 5 is not available here. I put everything back together and filled master cylinder and reservoir with DOT3. I started the truck and checked for air leaks on the air pack and tightened a few fittings. I then manually bled the air pack and started on the wheel cylinders from the back wheels.

When I got to the front wheel all of a sudden fluid started pouring from the vent beside the air filter! I started the truck and as the air pressure built up it was pouring even more!

I have checked my lines and I don't believe I have switched any. The vent has been removed from the master cylinder and the tee in the vent line was plugged.

I saw from a search that Gimpyrobb had a similar problem but the links to the photos didn't work.

 

[Junglemist]

With the truck running if I press the brake pedal brake fluid sprays all over the cab, hood, ground, etc. Somehow the vent line is pressurized. I must have made a mistake somewhere in the air pack rebuild.

Any ideas as to what I did wrong? I really hate to remove the air pack and disassemble it again without having an idea what I am looking for.

 

[G-Force]

If I'm not mistaken, the vent systm is connected to the master cylinder. Since you put a remotereservoir under the hood the brake fluid is basically overfilling the master cylinder and going out the vent line. Unless of course you disconnected and capped the line and connection to the master. The line should be connected up above the brake line fitting to the wheel cylinders on the side of the master.

 

[G-Force]

in the attached pis, the top line should be the vent and the bottom should be the line to air pack

 

[G-Force]

oops, sorry, just reread your post and realized you did disconnect the vent from th master. My bad......

 

[Junglemist]

I have removed the vent line from the master cylinder and installed a plug where it tees into the vent from the air pack. The vent line from the air pack is filling with fluid and when the pedal is pressed the vent line is being pressurized. The problem has to be in the air pack.