This is the later one piece style prop valve on my 73 with power disc brakes. The brakes blead just fine. With the engine off, the pedal felt normal...rock hard. With the engine running there was about an inch of travel, then the pedal was rock hard again. There was very little braking action obviously.

The other day I started the car and really pushed down on the brake pedal hard. There was a loud POP and the pedal went lower. After that, the pedal felt great. I put the car in gear but it wouldn't move. Something was holding it up. I jacked up the front end and the front brakes were stuck on but rears were free.

I pushed down on the pin that sticks out the top of the prop valve. The pin went down and the car lurched forward a little. The front brakes were now relieced. Last night I pushed on the brakes and the front locked up again. This time I loosened up the master from the booster. The brakes were still stuck. Pushing down on the pin relieced them.

Now a couple years ago, I did soak the prop valve in EvapoRust to derust the ousided. I can't remember how or if I cleaned out the EvapoRust from the inside. I did remove all the fittings and checked the O rings. I didn't try disassembling it any further.

Any suggestions as to what I should do next? Has anyone taken these further apart? I wonder if the valve can be removed from the prop valve body for a cleaning?

You have a valve sticking in it's bore. time for a teardown.

I just went thru this with a repop valve on a 1970 E-body, only mind were just slow to release the ft brakes (maybe 1 or 2 seconds delay)

So with that top fitting removed, I should be able to pull out the valve? That pin and everything should pull out?

There's some great information here. https://www.musclecarresearch.com/1970-76-mopar-combo-valve-autopsy

He has the later style valve for 73. I just happen to have this valve from a 74 sitting in my tool box.

I just pulled it apart, just for you.
Can't get a good picture with flash at this time.
There's alot in there and I'm sure yours is messed up inside from soaking and not taking it apart.
This one was stuck and I still don't have the spool out of the inside. I can slide it back and forth with a peice of welding wire, so it's not stuck. There is a bunch of debris in the springs. With this one I would use brake fliud to clean it out, KEEP MINERAL SPIRITS away!!

I think I would reuse this one since the valve slides back and forth inside. I'm not sure how to get it out yet to really make sure it is funioning properly and clean. I'm gonna let soak for while and I'll report back.

On your car your going to have to remove the whole thing from the car to disasemmble or replace it.

This isn't a brass unit but I assume the inner workings are similar. At one time I had one off of an 82 Cordoba. I'll look for it and take that one apart just to get a feel for everything first. Thanks for that link!

Thanks for taking that one apart Gary. I'll bet there is a bunch of dried EvapoRust in mine.

The two assemblies on the right in your picture were taken off and clean up after I soaked it. I think I tried removing the assembly on the left and it didn't come easily so I left it. That's the "pin" that is sticking.