spongy brake pedal

[Scrapper]

ok then try this take 1 line off master cylinder and put bolt in it off the same threads bolt master cylnder put foot on brake and see how it feel's then take other line out and do the same after hooking up line you just had a bolt in.. let me no how it comes out.it'll tell you where the air is.because it has to have air in or..you got me..

[vzfox]

Originally Posted by Daci

I have a 95 GMC 1500 P/U 5.7 V8 and I have the same spongy brake padel. Replaced booster, master cylinder, bleed the master berfore connecting the lines...everything that was said here but still the same spongy brake padel. My next move was to take the truck somewhere to bleed the antilock system but now that I've read this post I don't think that is the problem, since you said that you have bypassed it. Same like you I've bleed the brakes like 20 times, went through 4 botlles of brake fluid but nothing...I've just read that by pinching the rubber hoses to each of the wheels(pinch the hose and make preassure by pressing the padel and when you release the hose if the padel goes down there is your problem) you can tell if there is a problem with that specific caliper or cylinder. Meenwhile if you fixed your system please let me know what and how... Or if anybody else has some more info....Meenwhile I'll keep you updated if I fixed mine or not.
Thank you.

Well, it isnt quite "fixed" yet.....it is still spongy and not like it should be, but I have half of a brake pedal and it stops the truck just fine. I have exhausted my efforts and cant take it to a brake shop because I have bypassed the factory settings (ABS). I have also tried "Scrapper"s idea by capping off the lines at the master cylinder. The pedal did get somewhat stiffer with less travel to the floor, which told me the problem was in the brake line itself. But bleed after bleed after bleed....no avail. Like I said, the truck stops and I am beginning to dump too much money into it already. Much more and it'll have a FOR SALE sign on it.

[jeepfreak0iii0]

Sounds like we are having similiar problems. My friend has a 94 Sierra and his brakes are spongey after bleeding its dozens of times. The pedal goes to the floor and is slow to return. The master cylinder has been replaced twice this year and the booster was just replaced along with both rear drum pistons. There isn't much left to try. I'm going to have him try the isolation method by capping off the lines, but if you have made any more progress with yours, the help would be great. Thanks

[douglas92000]

Originally Posted by wheelin4x4

I would still consider air in the master cylinder. A quick story, a few years ago I was at a local repair shop where a friend worked, and watched as 2 techs spent ages trying to get all the air from a master, which can get trapped in little pockets, and be a you know what to get out. They tried quite a few ways to bleed it, and finally got all the air out of the master cylinder, when they ordered in a product called Speedi-Bleed from a local auto parts store. It was a little pressure bleeder that took about 5 minutes to hookup and within 15 minutes they had fully bleed the whole brake system including the master cylinder. Once the tool was hooked up, as soon as they cracked open the rear line from the master cylinder, you could hear the sound of the air pushed out, and they knew they had had it. The car was one of their contract police vehicles, so it was very important to get it done right before putting the car back on the road.

Watching that sold me on the tool, and I went and purchased my own Speedi-Bleed kit for my Toyota pickup, and have used it on many family vehicles. It gives a great pedal, though vacuum brake bleeder tools work good as well, but I think for overall use, and fluid flushing, this tool is hard to beat. Speedi-Bleed can be found at http://www.speedibleed.com

The alternative is the "Speed Bleeder" valves to replace stock valves. They perform as advertised and well worth the price(about $7.00 apiece) that turn a two man job into a one man job.

http://www.speedbleeder.com/