Ok, I have looked at all the forums and not found an answer -- maybe some else knows.

I have a 1995 Blazer. We have replaced the master cyclinder (new), replaced the Vacum booster, new wheel cylinders and new calibers. I replaced the front brake lines as well. There is all new fluid and the car has been power flushed. The system has no leaks as i do not lose fluid. But i still have a bad break fade.

The car stops fine but sit still the pedal just goes to the floor. If you take your foot off the pedal and hit it again the brakes return, but it fades to the floor again. I get no lights or anything.

Any Ideas???????

 

Did you get a NEW or rebuilt master cylinder? You are either leaking pressure somewhere in which case you'll see dampness at a wheel or hose, or you got a bad master cylinder. If the pedal drops and you aren't losing fluid, it's internal to the master cylinder. Go over the entire system, including pulling the rear drums, and look for leaks. If none, take the master cylinder back for a different one.

 

It was a new master Cylinder. we have looked everywhere for leaks and found none. i have replaced everything beside the ABS and main brake lines.

 

It sure sounds like a bum master cylinder. Then again, there may be something you dodn't notice and I'm not there to see it. Are the wheel cylinders in the back dry? All the rubber lines are dry at their attachment points? Is the fluid going down any? If these are all no, then there's a 95% probability of a bad master cylinder. There might be a problem with the booster but that generally causes other problems.

 

idk, even if the booster is bad it shouldnt make the pedal sink. sounds like an external leak or the internal master cylinder leak. Does the fluid level go down at all? I wonder if the ABS module can have an internal leak?

 

This problem has been get worse over time. First we replacde the Master cylinder with a new one, not rebuilt. Then I replaced the front brake lines. Then I replace the rear wheel cylinders. Then I replaced the brake booster. Now I have just replaced the front calibers. There is no noticable fuild loss or dampness that we can find.

I am left with replacing the ABS system or trying a new master cylinder agian, or replacing the main steal brake lines.

When we power flush the systems it is a little better for a day or two. I hope this helps, I am at a loss on this.