Continued from Brake Bleed Problem thread.


I have had a problem bleeding my rear drum brakes. I switched out the original power front drums to power front disks with all factory parts. The combination valve pin pushed in and has stayed in. Fluid flowed through the front bleeders with no problem but I had trouble getting fluid to bleed from the rear. This morning I removed the rear bleeder screws and stuck a plastic straw in the hole to move some crud and the fluid flowed.
Is there any way to force the pin out of the combination valve? I have opened one front bleeder and applied the brakes but it didn't move it back out. The valve was sealed up, but sat for 4 or 5 years. Does it sound like the combination valve needs replaced?

 

If it's a cast iron body, I would definitely disassemble and rebuild. There are rebuild kits with the o-rings available online.

 

Are you trying to re-use the original distribution valve from when your car had 4-wheel drums? Because, pretty sure you need to replace that with one designed for front disc/rear drums. With that said, if you have replaced the valve and unable to get that pin to move, maybe it's time to rebuild...or, just replace. Next time, consider buying a threaded plug that temporarily replaces the warning switch when bleeding. It holds the pin from moving when you're bleeding each wheel. Found mine on e-Bay for less than $10. When you're done, simply replace the warning switch. I just did this whole brake replacement thing and this worked great! And, contrary to some who are afraid you'll introduce air back into the system when re-inserting the warning switch, that is simply not the case.

 

As noted in many prior threads, the factory disk brake cars for 1967-1970 DID use the drum-style distribution block with a separate metering valve. The 1971-up cars used a combination valve that put the metering (proportioning) valve in the same housing as the distribution block. This was done for cost savings only, the two configurations are functionally identical. Either way works and both were used by the factory.

 

I am NOT using the Distribution Block from my 4 wheel drums. I removed that and replaced it with the Combination Valve before I even hung the calipers on the brackets. I changed that to the cast iron Combination Valve for the 71-72 disk brakes. I ordered a new Combination Valve from InLIne Tube yesterday, since I could not get the pin to pop out and reset itself.