ok here is the problem, my new project vehicle decided to lock up the front calipers on me, so i decided to replace them. while it was on the rack and i had the calipers removed i inspected everything and discovered i need new pads as well. that day i did not have the time or money to do so so i stuck the old ones on it. well two days later i got the money for some good metallic pads, so i stripped the wheels off and such and pulled the new calipers off, and since the new pads were almost 3 times as thick i need to press the pistons back into the calipers witha c-clamp. once i got everything put back togetheri took her out for a drive and discovered that my brakes hardly worked at all... so i popped the hood and discovered that i was spewing brake fluid out of the master cylinder cover. i immediatly popped the cover off and inspected it for damage(non visable). but now i can pump my brakes with the car off and they will get hard, but as soon as i start the car they go to mush and barely stops the car goin 15 mph. so i blead them and still same problem, does this sound like a master cylinder problem?? or more of a booster or proportioning valve problem??and by the way everything worked fine even with the near gone pads i could lock them up, but as soon as i compressed the pistons into the caliper and put the new pads on i began having this problem!!! PLEASE SOMEBODY HELP ME!!! I WANT THIS CAR TO GET BACK ON THE ROAD AND BE ABLE TO STOP!! HAHA...if ya'll could tell me how to test the booster that could rule that out...i am just so pissed at this car right now, i feel like beating the H*** outa it. thanks in advance for any input

Since the brakes worked fine before the caliper swap, the place to look is at the caliper installation. Are the bleeders on the top of the caliper? Possible one of the calipers is defective, with a vise grip pliers, clamp off the brake hoses on each side one at a time and start the engine and see if the pedal stays hard, if so, you have a defective caliper on that side. If the caliper bleeders are not on the top or near the top, you will have to switch them and rebleed the front brakes. Post more when you find out or if there is more problems, we are here to help.

i have the bleeders at the top pointed towards the upper fender

when i pushed the pistons back in for the new pads i had both calipers off at once cause i was not thinking straight....so i believe i might have broke a checke valve somewhere, no fluid comes out of the calipers but i bet taht i probably broke it doing this, so what i am goin to do is return the calipers and get new ones...if this does not work then i will look into something else like the master cylinder

ok think i figured it out...when i pushed the pistons back into the caliper, brake fluid began seeping out of the master cylinder...so the local shop think i blew the seal out of the master cylinder...only a 30 buck fix...will up date when i get the new one on and figure for sure that is what it is...

The hydrulic system was full of fluid when you started correct? so when you pressed in the calipers the fluid had to go somewhere.........the path of least resistance would say go out the master lid, right??? I know, I've do it too :rolleyes: , pretty messy huh? :eek:

I would suspect the second caliper may be blown out because as you stated you lost your head and didn't leave it on while pressing back the first one.

The master should be ok if it was good from the beginning.

Just a thought from here.

P.S. when I pressed in my calipers and leaked out the fluid I DIDN'T hurt the master cylinder.

i was told if the seal was blown in the second one that it would be spewing fluid when i hit the brakes...nothing so far...that is why i thought of the master cylinder...????i have no clue... :confused: :confused: :confused:

As brake pads wear, the fluid in the master goes down because the piston is farther out of the caliper. When you put new pads on the fluid level will rise when you compress the piston. If you filled it up when the fluid was low this will cause fluid to come out of the top of the master.

i was right...it was the master cylinder...i put a new one in (not remanufactured) and it stops better than it did before i started having the problems...