'93 Chevy Truck Brake Woes...

[ATEAV8GN]

Gents,

Got a problem with my wife's grandmother's farm truck... '93 C2500. Master cylinder was replaced on it two months ago. I had to drive the truck today and it damn near scared me to death the first time I hit the pedal. It goes soft until about an inch from the floor then its still not 100%. When I got back I bled the brakes, ran a whole quart bottle thru it, still as mushy. Pedal will firm up with the truck off and the pedal is 'harder' when bleeding the rears. Anyways, went and got another master cylinder, bench bled it , and put it on, bled the truck with 2 whole quarts, and still nothing. Brakes are in fine shape, new rotors and pads back in the fall, rears look fine as well. No calipers or wheels cylinders are leaking either.

Just thought to check the rubber lines but I don't think that a bulging or swelling hose would make the pedal this soft. If the vac booster was bad wouldn't the truck act like it had manual brakes and a hard pedal? Also when you depress the pedal (with the lid off the resivoir) should their be a 3" gyser like stream shooting straight up out of the rear half of the NEW master cylinder?

I don't like the thought of her driving at all but if she's gotta do it I rather her be safe, and others on the road as well.

Any help would be greatly appreciated as always.

TIA,

 

[TexasT]

Does it have AntiLock?

Is it equipped with anti-lock Brakes? My '94 Suburban has a Big box on the fender under the hood that the brake lines run through. This requires bleeding also as well as pushing the pins on the bottom point to the engine while you are bleeding. The procedure is covered in the shop manual. Check it out as these were the same symptoms I had until I bled them according to the manula. Good Luck.

Rich

 

[ATEAV8GN]

Yes, ABS, but...

Yes it does have ABS. but only on the rear. Something else I forgot to mention earlier is that the brake light on the dash is on as well... ggod thought about the abs, I will have to try it in the morning.

Thanks,

Drew

 

[tjthorson]

I had some symptoms on my 97 that were similiar. It turned out to be the vacuum booster. There was a small hole in the big rubber diaphragm. Car was only 3 years old and 36K!!!! A new one from the dealer was over $300. Used GMPARTSDIRECT.com and got it for like $180.00

Is there a hissing when you step on the brake? I remember the engine stumbling a little too - like a vacuum leak.