Brake Problems - Won't bleed, leaking out of master
 

The last piece of the puzzle before I can drive my truck home is the brakes. There seems to be a problem that we can't quite figure out. The lines won't bleed and they keep pumping fluid out of the rear of the master cylinder.

It's almost like there is damage inside the slave or master cylinder.

Is this something that happens when these trucks have been sitting for too long? It was working great 4 years ago - but that was 4 years ago.

Any help would be appreciated! Thanks.

1972 Chevy Super with Brake Booster

Re: Brake Problems - Won't bleed, leaking out of master
 

When you say it's pumping fluid out of the rear of the master cylinder, are you talking about where the plunger is -- where it attaches to the vacuum booster? That's definitely not right and you'll need to replace the master cylinder.

Still seems like you should get some fluid through the lines though, unless they're blocked. A more likely problem is the bleeders are plugged, which is common. If so, just remove them & clear the blockage (probably mud) then screw 'em back in.

Re: Brake Problems - Won't bleed, leaking out of master
 

Yes, replace the master cylinder. Replace all three rubber lines if they are the original. They may look okay on the outside but the rubber will swell on the inside and prevent the fluid from passing through or restricts it. Not worth the trouble later on.

While you're at it, you may as well do a complete brake system rebuild. I spent a little over $200 but it was well worth the effort. All new shoes, springs kits, wheel brake cylinders, turned the drums and replaced all three rubber brake lines.

Re: Brake Problems - Won't bleed, leaking out of master
 

Also,flush all the fluid.It will absorb water and can cause rust in the new parts and will affect your braking.

Re: Brake Problems - Won't bleed, leaking out of master
 

master cylinders are $15 lifetime warrenty at a parts store... they are cheap cheap cheap

Re: Brake Problems - Won't bleed, leaking out of master
 

Leaking M/C's are bad....mmmk

Re: Brake Problems - Won't bleed, leaking out of master
 

True. I bought one this evening. Hopefully it solves the issue. Will update tomorrow.
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Re: Brake Problems - Won't bleed, leaking out of master
 

We got fluid to all four brakes, we already cleaned the bleeders. It's just when you pump them up, it emptys the front bowl into the rear bowl and forces the fluid out the top. We think the splitter valve might be bad, under pressure it fails and sends the fluid back into the rear bowl of the master cylinder.
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Re: Brake Problems - Won't bleed, leaking out of master
 

With a new master cylinder and help from this thread: http://67-72chevytrucks.com/vboard/s...d.php?t=241722 we were able to get the brakes working perfectly.

Thanks for your help everyone! :metal:

Re: Brake Problems - Won't bleed, leaking out of master
 

right on good to hear!