Help!! '87 S-10 brake problem

[Opie2211]

I have an '87 S-10 with manual brakes. When I bought the truck it had been sitting for almost 2 years and the rear brake line (along the frame) was busted, so it only had front brakes. Well, I replaced the line and when I tried to bleed the brakes, I got no fluid at all. I tried taking the line directly off the master cylinder to see if it would come out there but it didn't. So I bought a new master cyl. and it did the same thing...no rear fluid. I thought it was bad too, so I took it back and got an exchange and still yet, after another new master cyl., no rear brake fluid pumping through the system at all. My only guess left is the proportioning valve. Could this be the problem? Maybe stuck in full front assist mode? Any help would be greatly appreciated. Thanks!!

[Oldtruckfanatic]

Hello...If you took the rear line off of the master cylinder directly and no fluid came out then the problem is air in the master. the way the valve works in the master if there is air in it it won't draw the fluid into the plunger part of the master. In most cases you can bench bleed the master cylinder and get it working. The problem is that with the front brakes pumped up the plunger sometimes won't travel far enough to allow the rear port to pick up the fluid so it's important to get the rear brakes to bleed first. If you don't have the stuff to do the bench bleed remove the rear line from the master (make sure you put rags under it to keep it from dripping on the paint on the inner fender) then depress the brake pedal and have someone crack either front bleed screw so the pedal goes to the floor, Then hold the pedal there for a couple minutes and see if the rear port starts to drip brake fluid. if it does not have the buddy close the bleed screw and release the pedal and again push down the pdal and have the buddy crack a front bleed screw so the pedal goes to the floor. If fluid doesn't squirt out of the rear port when it goes down hold it to the floor for a couple more minutes to see if it will gravity bleed. This process always works for me but sometimes it takes two or three tries. once you get the fluid hook up the rear line and bleed the brakes rear first then front make sure to thoroughly wash any part of the truck that gets fluid on it right away so it doesn't eat the paint.Hope this helps.

[Opie2211]

Thanks for reply!! This is very helpful...I haven't tried that yet, but will do so right now. Thanks again!