seized distribution valve piston- easy solution

[DDAN1130]

So my warning light had been on on my 69 F100 4x4 and I only had front brakes. I didn't drive it over the last couple of months anyway since I was building the engine and doing tons of other stuff. Anyway I just got to it and racked my brain as well as the internet to figure out a solution. I had to cut the brake lines going to it since they were all seized up and I had pretty much already ruined the fittings anyway. Once I got the actual valve away from the frame I took off the cap and removed all of the fittings to inspect it. There was a lot of corrosion visible so I put it in a butter container submerged in PB Blaster for 2 and a half days or so. While it was soaking I started searching the part stores for fittings. I ended up getting everything I needed from 2 different NAPA stores. (If you're in Tampa, the NAPA on Causeway has a couple of great dudes working there who are just as in to your stuff as you are). What I ended up getting was enough tube thread cap fittings that blocked off everything except one of the rear brake fitting holes. I also got the a package of the smaller fittings and THREE of the larger (these were loose behind the counter and not in boxes of 5). I got the third to use as my rigged up hydraulic fitting. NAPA also had the hammer in type of grease fittings. I used that third fitting and drilled it out just enough to be able to hammer in that grease zerc. once that was done, i threaded it in to the open rear brake inlet and made sure everything was tight. then I just hooked up my grease gun and started pumping. It didn't really have to build up as much pressure as I thought but it did get a little stiff to pump the gun and then the piston just gently popped out. then I used a combination of brake parts cleaner, wd-40 and my gun cleaning kit to clean all of the ports and threads. I got the "rebuild kit" (2 square o-rings and a copper crush washer) from Muscle Car Research for about 8 bucks. I put on the new orings and that was that. Much easier than I expected once I gathered up all the necessary stuff... hope this helps the next one who has the problem.

[Nitekruizer]

Thanks! This is a problem that I still have to fix.

[DDAN1130]

no problem! I also went ahead and bought the little cap screw with the post on the end to keep the piston centered while bleeding the brake system from Muscle Car research. I think it was 10 bucks or so but should cut out some hassle.

[ultraranger]

WD-40 squirted onto the O-rings will probably lead to their destruction shortly. The O-rings are designed for brake fluid (synthetic). WD-40 is petroleum based and will swell the seals.

Hopefully you didn't get any of the WD-40 on the new O-rings or left any WD-40 residue inside the valve.

If you know what side the pressure differential valve spool had shifted to (rear brake circuit for example), you could have opened a bleeder screw on the front brake circuit and pressed the brake pedal down until enough pressure was built up, to shift the valve back to the center and turned the warning light off.

Muscle car research also has a valve lock tool, to install in the pressure differential valve body, so the spool doesn't shift while you're bleeding the brakes out.

[DDAN1130]

I made sure to flush the valve body in brake fluid after I was done cleaning it with a bore brush. The new o-rings never came in contact with the WD-40. I tried to use the bleeder valve and brake pressure to break it loose but had no luck. The light was on when I got the truck and then it sat for another 6 months while I was building the rest of it so I have no idea how long it was shifted over the rear brake circuit. I do know that the inside of the block looked horrible and wasn't cooperating in it's current state.
I got the tool and tried to explain it in my post but probably not good enough. Those are really good points that I should have put in my post, so thanks for the extra info! At any rate, it gave me a good excuse to add a double flaring kit to my tools, sooooooo I guess I won even if it could have been done differently...