After spending far too many hours trying to figure out what's going on with my brakes, I still have no idea what's wrong. Can anyone help? 1985 4Runner, new to me so no prior experience. This is a long one, but I'd really appreciate the help.

I only have front brakes and BARELY this at best. With the truck on stands and the brake floored, you can turn the drums easily by hand, but the fronts hold. On the ground, you can hardly keep the truck from rolling with the brake floored. So, basically I have no brakes, very low pedal, pressure does not build at all. Here's the two tricky things that have me baffled.

1) Rear doesn't get any pressure.......when I open the bleeders on the drums, the pedal does not drop at all and fluid barely comes out. When I move up to the BPV and do it, the pedal drops like it should. The calipers bleed properly also. So, I thought maybe a rear line was clogged.....nope, I disconnected it and blew through it and fluid movely freely. So, I thought the BPV was messed up, so I switched it with my parts truck's......nope, no change at all. So, for whatever reason NO PRESSURE is making it to either rear drum, it IS making it to the BPV and calipers, but thats it.

2) Air bubbles in master cylinder.......they are always there. For 30 seconds after pumping with motor off, air bubbles comes up just like it was carbonated, lots and lots of bubbles streaming up. Even after a while, the occassional bubble comes up. I don't think the MC should have any bubbles in it. No leaks that I can find anywhere in system.

I've bleed the system properly many many many times, so its not that. I've broken open many of the connections to see if air was trapped at joints and found no problems. The truck has new calipers (not related to this problem, and did this before new calipers) so that's not the problem.

My only guess is that the MC is bad and somehow not pressuring the rear of the truck. Those air bubbles (lots of them) doesn't seem right. Also, whenever I pour fluid in it, the level increases and then drops a good bit. Does this every time, I'm not sure where the fluid goes, but it has to go somewhere.

I am not positive how the BPV works, but this is what I'm thinking....one line runs to the BPV from MC to feed it and one line runs out of the BPV it back to the MC, with the third line actually feeding the drums. Does this sound right? I had always thought the two lines connected to the BPV were one for each drum, but after looking carefully, I don't think this is true. I guess the one line that returns to the MC is to monitor pressure from the BPV. I think the problem lies either within this line or withing the operation of this in the MC.

Alright, that's my story........I am pretty frustrated <img src="/forums/images/graemlins/angry.gif" alt="" /> with this truck. Seems like one problem after another (now it won't even try cranking over...starts with popping clutch, and the radiator is leaking), more on these later if I run into questions.

Thanks for the help <img src="/forums/images/graemlins/confused.gif" alt="" />.