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Old 03-07-2013, 01:43 AM   #5
Join Date: Mar 2013
Posts: 7

Originally Posted by Ssicarman View Post
Why did you change the master cylinder?

Air in the hydraulic system will give a spongy pedal. Air has a hard time compressing like a fluid. Given this it is very unlikely that it will expand with heat to give you a hard pedal.

Dragging brakes mean that you have something holding hydraulic pressure on the system. If it began with the master cylinder replacement then this is where you need to start looking for your cause. I would unbolt the master and pull it back from the booster to make sure that the push rod is in place properly. If that is ok then you may have a problem in the booster.

With an intermitant problem you may have a time finding the problem.
AWesome! Thx for the reply. I changed the MC due to it leaking inside the booster. So I got a cardone rebuild from Oreilly. Put it in and it worked well for a while. Then about a month later, I began to get a slightly hard pedal feeling and noticed the car would drag slightly when that sensation would occur. Doesn't lock, just drags likevyour barely touching the brakes. Enough to make the car not move at idle at D. I changed the booster valve. Cheap but didn't fix it. Also, I don't loose power assist at all so it's not the booster. Sometimes. .. When it does it at stop and go traffic, I will get the hard pedal feel and I push the oedal hard like 3 pumps, and suddenly it goes back to normal. Sometimes I don't pump it at all and I feel the pedal drop slightly and is normal again. Weird. I suspect you are correct. There's pressure build up causing it. But what do you think about the booster valve trick? If it begins to drag, I pull over and leave it at neutral, unplug the booster hose check valve from the booster and as soon as I hear the vacuum hiss, the car rolls freely. What the heck!
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