The Stovebolt Site Forums The Shop Area General Truck Talk Master cylinder rebuild question

I purchased a rebuild kit but can't seem to get it to work. No break fluid makes it past the piston and out into the lines.

What am I doing wrong? What sequence does this thing go back together? I didn't take apart the original so I don't know exactly how it goes back together.

Just a guess, could the rubber cups be in backwards? The linkeage has to be right. I dont know how you can tell that. I never messed with the linkeage because a good mechanic told me years ago to leave it alone as I could mess things up bad. I bet someone here will know just what your problem is.

InMy40s, look at my webshots pictures below and under huck brakes and you will see all the parts in order to rebuild the master cylinder for my 1946. I hope this is what you were looking for as my master cylinder is now rebuilt and works.
Jamo

My guess is that the "check valve" is installed back wards but that is just a guess. Did you mic the cyclinder to see if it is within spec? This is one of those things that "if I could see it and put my hands on it" I am sure we could spot the problem right off. Let us know what you find.

It's situations like that that some good digital pictures come in handy. Now that I've got a digital camera, every time I rebuild something, I take pictures along the way so I (or others) can benefit later. Hopefully someone has done the same for the MC.

Rance

Thanks Eric, your pics confirmed that I have everything in the correct order.

I had the cylinder honed by a local shop, so it may no longer be in spec.

I'll try priming the space behind the piston to see if that helps. If not, I'll have to order a new one.

Thanks everybody

InMy40's You may want to look and see if both (yes there are 2 one large and one small) holes from the reservoir are both open. Just a thought. One more thing did you bench bleed the MC or did you install it and then fill it? Have you tried to disconect the main line and see if you are pumping fluid out of the MC? Good luck.

i believe brian has the right idea here. you have to 'prime' the mc before you install it or you'll be dry pumping for hours.

I just honed out my master cylinder and cleaned it out real good and made sure both holes were free of anything, installed new rebuild kit and installed on truck and filled with brake fluid. I did not bench bleed it and it took only a couple of pumps and fluid was squirting out of the back of the master cylinder. I reconnected brake line and bled entire system and I was on my way.
Jamo

Turn out to be the second hole was plugged. It took a punch to get it clear. Once that was done it worked right away.

Thanks for all of the help.

Glad it was a simple fix!