Hey guys, long time since my last update.

I purchased a reconditioned master cylinder from Summit, it replaced my midland one on my 64 F350 with power booster.

I installed it, went through the break in procedure, but something seems to be wrong when I tried bleeding it. I installed the new lines, new hoses, new wheel cylinders, everything is new. I loaded my master cylinder with fluid and opened my bleeders and let gravity bring the fluid to each wheel then closed them. (Please correct me if I am wrong) I then opened one at a time and played the up and down game a few times to make sure I have the air out, but the pedal goes to the floor every time, I don't think there is any more air in the lines.... When I depress the brakes, I can hear air blowing out somewhere... it seems like it is coming out from where the 2 halves of the booster come together... is that normal? When I start the engine and depress the pedal it goes to the floor like a feather (which means the booster is doing its job)... I I am at a loss as to why I have no pressure building up.

Any Help would be appreciated.

Thanks everyone, and have a great Thanksgiving!

 

Remove the master cylinder, bench bleed then reinstall. I use short lengths of tubing connected at each master cylinder connection - these are just open pieces that are submerged in a jar of clean brake fluid. Push the plunger in manually using a pry bar or large Phillips screwdriver repeatedly until no bubbles are visible in jar. Reinstall master cylinder and go through the bleeding sequence far too near.

 

Thank you for the reply, I believe I found my issue though, when I depress the pedal the pedal returns but the cylinder in the master does not retract with it, and it stays in the depressed position, and the same goes for it when it is off the vehicle and without fluid....

Seems like I got a defective master cylinder.

 

Did you upgrade to a dual bowl M/C? Now would be the time to do it.

 

I did not upgrade, I just want the damn thing to work, the brakes are my last hurdle before I can drive it. But that new m/c didn't work right since it wouldn't spring back open after being depressed....

 

My Master Cylinder Video

 

That does seem completely horked, doesn't it. Still would try bench bleeding, there's no fluid in there now?

 

I tried bench bleeding per the instructions on the paper that came with it but it was unclear.

Yea it is that difficult without fluid in it... its even more difficult with fluid in it.

 

Well I think you got a bum cylinder... But not sure either. It has to be bled though, either on the bench, or on the firewall.

That is, prior to hooking any lines up and proceeding with a normal brake bleeding. It starts out easy at first, with lots of bubbles. Eventually, extremely hard to move the piston, and only a bit of foam. I let mine sit overnight and hit it again before installation.

 

Seems you still have air in the system..the the peddle come up if you pump it really fast?.. Easies way to clear the air is a vacuum pump..or you could just open up all bleeders and let gravity do it's thing over night..( dont touch the peddel Just make sure you top off master and keep all the hose attached to the bleeders submerged...

Good luck

 

Thanks for the reply,

Thats what I thought too, but when I press the pedal down, it doesn't come back up really at all because the master cylinder gets stuck in.... Will that change once the lines are gravity bled (I don't have a vac pump). I'm afraid once I get all the air out I still wont be able to get that master cylinder to retract when the pedal is released...

I bench bled mine again this morning, same result, piston sticking when I push it in...

I called summit and they are sending me another one (in 2 weeks). This whole brake situation is new to me.

 

I'm pretty sure the pressure from the fluid pulls pedal back up... Is the valve bottomed out... Do you have any movement..if so pump it up quickly and see if each individual pump raises the pedal height.. If you installed the master before you bleed the master you have a lot of air in the system...

If the master is installed on the car... Close all the bleeders pump up the brakes and while someone pushes on peddle ... Crack the fitting on the front of the master just enough for some fluid to escape... If you don't have back pressure the pedal is not going to come back up...

Please describe how you are bleeding the brakes...since I'm not sure if you have done his before I need to ask... Your not letting he peddlel go all the way down before you close the bleeders correct?.. Make sure whoever is pumping the peddel holds it hard on the last pump and you just open the bleeder for a second.. Do it a few time and the strokes will lengthen...

 

Also in the picture the hose does not look submerged in the brake fluid.. If its not kept completely submerged air is rushing right back in..

 

Well I did not get too far into the bleeding, my buddy pushed the pedal down about halfway down, and then close the bleeder and raise the pedal and open bleeder briefly, and have him push down on it, but i noticed that the 2nd time, there was no movement of fluid in the line connected to the bleeder... then I took the master cylinder off and realized that it was stuck into it and hadn't retracted with the pedal....

And the pic is an optical illusion, the line is submerged in the fluid.

 

You wrote your buddy raised the peedal and you opened bleeder... You should only open bleeder when he is pushing on pedal ... Another option would be to bleed with a syringe.. Connect the hose they included to bleed master,, then use a syringe or squirt bottle full of brake fluid and force brake fluid through the hose .. If there is air in the master you will see it come up the master.. Good luck