1995 Ford Escort Power assist diminishes brakes

GKNIGHT

MEMBER
1995 FORD ESCORT
4 CYL
2WD
AUTOMATIC
250,000 MILES

The car sat for three months and somehow adsorbed water in the brake fluid. I bled all the brakes (considerable mirky and even reddish fluid came through until the new stuff, and checked that calipers and slave cylinders actuate fully (even removing pads to extend the travel, with care not to pop the rubber seals of course), and retract with a clamp. The pedal then felt adequate (high, with firm grab on the rotors about half-way). But as soon as I start the car, the power assist seems to remove all pedal. I.E. It has no brakes other than the parking brake. The car and brakes have given great service all these kilometers, with reguar maintainance, yet this behaviour has never occurred. What could be wrong?

3 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Check the master cylinder and brake booster

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Friday, April 24th, 2009 AT 10:16 PM

GKNIGHT

MEMBER
2 POSTS

I am not impressed with that response. There's no reason from the symptoms to suspect the master cylinder, which was working fine before over-wintering; and the brake booster wouldn't do what I've been finding even if the check valve was faulty. There was some braking force before the engine's turned on, which disappears with power assist, and that would happen whether the check valve was faulty or not. Turns out the real problem is a pinhole leak in one of the rear lines, which wasn't obvious under normal bleeding pressures. I noticed the damp ground under the culprit union and took it from there.
Please credit my $10 to a later question (I'm sure a car of this age will have other issues).
Thanks,
Gary Knight