A month or so ago I replaced the master cylinder on my 91 (auto, 134k on the clock). Helped my crappy brakes a bunch! A week ago, the usual "turn the key, wait for the fuel pump, start" went to "... fuel pump, turn over a few times, start" to ".... turn over a bunch of times, try a 2nd time, start". Strange part #1-runs like a scalded dog. Even with an old auto and a new set of Falkin 452's, shift to 2nd gets a chirp.
Heading for work today, late, no challenges until I was 3 blocks from the office. Hit the binders at 45 mph and the pedal was rock hard. Evasive turns, a real close run next to the gutter and right turn on a red lite, and mashing on the pedal got it whoa'd up.
Checked for cracks in the booster, fractured hoses - nothing visable. Except - Strange part #2 - the MC reservoir for the rear was overflowing and the front reservoir seemed down to about 1/2. I usually keep them about 3/4 full, change fluid more often than shirts, bleed about every other month, if not more, especially for AX.
I did pull a vacuum test on the booster. At idle, I have about 20" vacuum at the booster check valve. Apply the pedal, it goes to about 10". Pulled the manifold hose and attached the Miteyvac to the booster check valve and got 0". The check valve is ok, don't find visable cracks in the booster so I'm guessing the diaphram is toast. Ok. Booster # 4 (#3 is a metal one about 1 1/2 years old).
What I don't understand is the overflow from the reservoir. The proportion valve may have stuck open? The sensor checks ok now.
Any brake gurus out there have any ideas, 'cause I'm fresh out
T.I.A.
Subman