No fluid to rear brakes when trying to bleed

[smithdh]

I put new brakes and wheel cylinders on my 92 Explorer but I can't get the brake fluid to flow so I can bleed them. I noticed it didn't even dribble when I took the old cylinders off either.

The master cylinder is full, why won't it flow the the rear brakes??

Gravity wouldn't work and my wife pumping the pedal whith the bleeder screw closed, and I opened it while she held it didn't work either.

 

[Opera House]

The antilock closes off

You have to use a mighty vac.

 

[smithdh]

Mighty-vac didn't work

I borrowed my brother's mighty-vac. It'll pull good vacuum and slowly taper off but I can't get any fluid. I cracked the lines at the master cylinder and have pressure and fluid there when the wife steps on the pedal. I opened the line that goes to the back along the frame where is comes out of some kind of proportioning valve, no juice there. I noticed that the line from the master cylinder to that valve had been against the exhaust pipe, it shows signs of rubbing but doesn't seem to be leaking. Do you think the heat may have done something? I am stumped.


Perplexed,
Dave

 

[X-1]

I would crack the line at the point where the rubber line meets the steel line at the rearend, at least isolate where your problem is. Maybe bad wheel cylinders? You should be able to gravity bleed them.

 

[smithdh]

I put new wheel cylinders on

There is no brake fluid going to the steel line ahead of the rubber hose that goes to the rearend.

 

[smithdh]

THE SOLUTION

Somehow, the line that goes from the master cylinder to the rear ABS valve was bad. (in the old days we called it a proportioning valve). The steel line had been rubbing against the exhaust pipe just below the exhaust manifold. The line will not pass any fluid. I put a hand vacuum pump on the line after I took it off and it will hold 20" vacuum for quite a while.

I bent a new piece of line from the master cylinder to the ABS valve, the fluid came right on through. I let gravity push the fluid to each rear wheel, had my daughter pump them a couple times for the final bleed and we are in business.

I want to thank everybody for their suggestions. I was stumped on this one.
By the way, it stops a lot better now too.