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Old 11-04-2012, 06:15 AM
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Originally Posted by davidmij

I was reviewing my posts this morning and realized I never posted what I found on my brake issue.

The company sent me a 9 inch power brake booster to replace the 8 inch - it didn't help,

...but now I was getting brake fluid bleeding out of the MC after driving the car and applying the pedal.
The 9" booster will give higher line pressures.

I googled around and found that a couple of things could cause this. One was a frozen wheel cylinder or caliper. If one of your wheel cylinders are frozen, it can cause extra brake line pressure which can cause your brake fluid to leak around your master cylinder cap.

I inspected each brake and found one of the rear drum cylinders wasn't working. This caused brake proportioning valve to cause excess back pressure and favor the front brakes.

I had previously checked the fluid pressure at each wheel but that doesn't show you if the wheel cylinder is working or not. After replacing it the MC no longer leaked. The brakes are much better now, but still not as good as I would have thought

Just thought I would update this in case anyone was using it.

regards, Dave J
Fascinating theory. You might check the MC mounting to see if the excessive pressure also caused bleed-by at the MC piston possibly causing mild hydro-static lock-up.

It may also be that the MC piston stroke is too long, possibly causing damage.

**** good diagnostics...
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