I had to switch a leaking master cylinder on my car with a remaned one. 67 drum/drum with 46 Ford brakes front and 57 chevy rear 10lb residual valves both front and rearm, master is under the floor. Bench bled the new master and installed it, bled the brakes and noticed that the cap is leaking, pretty good too, I swapped the one that it came with and added the chrome one I had on the other master and it still leaked, from the back only, on both. The pedal is firm but real low, so may have air, but when pumping the pedal with the cap off it pushed fluid up and out of the master is this normal?, Any ideas?
you shouldnt be pushing fluid out when the cap is off. i think you have a blockage in the system somewhere. you will still have a firm pedal but it will be low due to the lack of fluid. this happens with reman parts. since they hone the cylinder sometimes they dont get all of the metal out. once you get fluid in there it will psh everything to one area causing a blockage.
if you pump your brakes with the cap off you will see the little fountain fluid makes when the pressure you just pumped into the system returns, this could be what you seeing, it can shoot right out the top and make quite a mess, usely when my peddle is firm but low its do to the brakes needing to be adjusted up some.
OK, what should I be looking for when adjusting my brakes, slight drag? You are correct about the fluid shooting up, but why then would it leak out past the cover?
What is the correct method for adjusting 1946 Ford brakes? I am going to try to adjust all of them (4 wheels) tonite. I read that if I adjust the rears to where they wont turn than back off 7 turns, or clicks that would set the rear, and then I have to adjust the fronts. I may have run the master down to empty after it was bench bled, my 8 year old helper was pumping the brakes as I was getting ready to bleed them, so I may have to remove the line and bleed the master again. The trick is the 46 ford adjustment with just the 2 adjusters...
so i think you have a 67 ford master, and you installed 57 chevy residual valves, did you check to see if the master came with valves already installed?, to adjust any drum brakes you have the car up so the wheels can be spun easly, adjust your brakes till you get some drag when you spin the wheel, get in and step on the brake peddle, this helps to center the shoes in the drums, get out and give the wheel another spin, most likely there will be no drag, adjust your brakes again till you have drag that will stop the wheel at one full turn on a good spin, then go to the other side and do the same, i start with the rear brakes and then do the front setting the front brakes to have just a little more drag then the rears. as for your 2 different covers leaking did you use the same gasket on both?, have you looked to see if the is a casting flaw where the gasket would sit?, are you over filling the master? should be down about 1/8" to 1/4" below the top.
The covers each had their own gaskets. I did fill that ****er up to the top, so that may be problem#1.
If you still have air in the lines, pumping the brakes will compress this air. When you let off the pedal the compressed air will force fluid back into the master cylinder with enough force to make it squirt out the top.
also some new cover gaskets that come on rebuilt and aftermarket masters do not fit right, i have had some that were just to small.
I just re read the first post and I worded it like ****, here is what I have: 1946 Ford Drum brakes up front 1957 Chevy rear drum brakes 1967 Mustang Master Cylinder 2, one for the front and rear, 10lb wilwood residual valves. Had a good pedal but the original master leaked from the area where the pushrod goes into. I got a new one and bench bled it, and swapped it out. I may have run the front part of the dual master dry before bleeding the brakes, but with a preliminary bleeding of the brakes, I have a super low pedal and a leak from the cover. What I plan on doing was adjust all 4 brakes again, and then bleed the master again, then try to bleed the system. I have to figure the way to best adjust the 46 Ford brakes, and hopefully with less fluid in the master the cover wont leak. Hope that clears it up.
Dooley, just went through this battle this weekend. Installed the very same m/c you mentioned, '67 Mustang/drum/drum setup. Pair of 10# RPV'S. We bled the brakes no less that 6 times. We even vacuumed them. Still had to pump twice for a brake, and it would go back to sponge after 5 seconds. Replaced the m/c yesterday, bench bled it, installed, pumped and made a world of difference. Bled them once, but will do again tonight. ***** is, still must pump 1-2 times for solid pedal. BUT - bleeding one more time whould get that fixed. Hated the fact the reman m/c was ****. Oh yea, my lid leaks too. Anyone got a fix for that?
Alrighty then, re bled the master cylinder, adjusted all four brakes, and bled the whole system and I have the best pedal I've had. But the goldurn cover on tha master is still leaking...
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