72 rear brake bleeding problem

[Matthew S.]

I'm hoping someone can shed some light on a problem I'm having getting brake fluid to my rear brakes. I just rebuilt my calipers, replaced the rubber hoses and rebuilt the master cylinder. I bench bled the master cylinder and got good fluid flow in both the front and rear halves of the master cylinder. I installed the master cylinder on the car and used a MityVac to bleed the front brakes with no problem. However, when I tried to bleed the rear brakes I couldn't get the MityVac to pull any fluid through the lines. I tried for a while and finally decided to try the manual method of having someone step on the brake pedal while I open and close the bleeder screw. This also didn't push any fluid through the lines. When I press the brake pedal with the rear bleeders open there's a lot of pressure. The pedal doesn't go down easily like I would expect it to. Does anyone have any ideas on what could be causing this? Is it possible that the distribution block is bad? How would I test to see if that's the problem.

Thanks for your help - Matt

[lyndon sharpton]

Re: 72 rear brake bleeding problem

has the car set up a long time? you could have trash are rust in the block, give that a look

[John O.]

Re: 72 rear brake bleeding problem

Hi Matt

Did you try both sides on the rear or just one?
Try taking one bleeder screw completely out and have someone push the brake pedal slowly to see if fluid comes out. If it does, then replace the bleeder screws.They get plugged sometimes.. The only suggestion I can give you to test the distribution block without removing it is take the line apart at the master cylinder and the closest connection on the other side of the block. Try to connect your mighty vac to one side and make sure it is sealed tight.As you start squeezing the handle, you should NOT show vacuum if the line and block are clear. If you show vacuum and it holds, then you have a blockage most likely in the block. Also you said you just rebuilt the calipers? Try taking the hose off the caliper and see if the brake fluid flows. You might of done something wrong in rebuilding them. (I would do this first.)

Good luck.........John

[Matthew S.]

Re: 72 rear brake bleeding problem

Thanks for the feedback,

Lyndon - The car was sitting for about 2 months while I rebuilt everything.

I did try bleeding both sides but neither side worked. The bleeder screws are new so it's unlikely they're plugged. I'll try your idea about the distribution block. If that's not the problem then I'm going to test each component starting with the master cylinder. Never having rebuilt a master cylinder before it's possible I did something wrong there but I was really careful to get the seals on in the proper direction.

Thanks again for your help.

Matt

[Gary R.]

Re: 72 rear brake bleeding problem

Check the bleeders, I found "new" bleeders that were not drilled out completely. The Might Vac is a good testing tool but a lousy bleeder. Get a Motive bleeder for $60 it is worth the money. Good luck