bad brakes

my 91 park avenue has no brakes...i put a new master cylinder on and the pedal still goes to the floor...while i was bleeding the brakes it began to gain pressure but it all just goes away....i thought about blowing the lines out...what do u think

Why was the M/C replaced? Same issue? Did you bench bleed it? What is your procedure for bleeding the system?

BTW, very interesting user name you've selected, very cheery :lol:

yes i replaced it for the same reason...i was told it might work...i dont know what bench bleeding is but when i bleed them i get somone to pump the brakes a few times and then hold it to the floor....then i loosen the bleeder valve and let the air out and then close it before they let off the brakes...i repeat this on each tire till no more air comes out...my s/n btw is my game name in americas army

If you did not "bench bleed" the master cylinder, you have air in the whole system.:nono: Here (http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/17/fa/f2/0900823d8017faf2.jsp) is the basic bleed procedure to use.

so if i take it back off and check the rings then bench bleed it and put it on again will it work?

so if i take it back off and check the rings then bench bleed it and put it on again will it work?
More than likely, your master cylinder piston bore is full of fluid (and some air) by now. You do not have to remove it for a “bench bleed” at this point. You can follow the procedure for bleeding the master cylinder as installed. (Breaking each line one at a time)


A little food for thought; The master cylinder has a 1” (or larger) bore and is 6” to 8” long. If you did not rid the cylinder bore of all the air before installing the master cylinder, (bench bleed) you pumped the air from the MC bore into your brake lines.

Be patient, bleed the MC again and follow through with the bleed procedure on each caliper or wheel cylinder. It will take several attempts, with all four, to get the air removed!:smokin:

ok cool ill do that...thanx...another thing i did is pulled the line off and the fluid that ran out was nasty...it had dirt and grit in it...should i blow the line out to get all of this out before i try bleeding them again?

ok cool ill do that...thanx...another thing i did is pulled the line off and the fluid that ran out was nasty...it had dirt and grit in it...should i blow the line out to get all of this out before i try bleeding them again? What line are you referring to, the rubber line, or the metal lines? You can rid the system of old fluid and grit with a "power flush" system or by continuing to bleed the caliper/cylinders with new fluid. It sounds like the trash in the system, is what caused your MC to fail. When changing brake pads on an ABS system, it is very important not to compress the calipers without first opening the bleed screw while compressing. (This is also a good practice on all brake systems) If you do not open the bleed screw, you will force all the grit, grime & water, back into the MC reservoir and destroy the piston rings, then eventually, the ABS system. The complete brake system, should be flushed at least every two years. :grinyes:

alright...thanx...do u have anything i can read on the "power flush"

alright...thanx...do u have anything i can read on the "power flush"
Try this (http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/17/fa/f2/0900823d8017faf2.jsp#hd1-1-2)