Toyota: Brake pedal sometimes goes half way to floor, leaky seals, cylinder seals

Question
Sherry, no one else is available. This might be out of your expertise but here goes anyway. I have a 89' SUPRA. Sometimes when I hit the brake the pedal goes half way to the floor before starting to stop the car. If I release the pedal and push it again I have a full pedal. This only happens intermittantly, but it just started all of a sudden. The brake resevoir is full and most of the time I have a full pedal, but it is starting to get more frequent. Any thoughts on what is causing this. Could the ABS system be at fault or just the master cylinder starting to fail???? help!   thanks Pete  

Answer
Hi Pete,

It sounds like a brake cylinder seal/lining problem.  Check the backs of all the wheels, is there anything splattered on the backsides of the tires/rims?  If there is, then you have a blown out wheel cylinder.  If not, then it sounds like the master cylinder seals are leaking back.  Either way, you need to get it fixed ASAP, this could be extremely dangerous. Worn/leaky seals usually don't stay intermittent for very long before they totally fail.

It would not be the ABS, your ABS indicator would come on if there were a problem with that system.  If the ABS failed, it just wouldn't "buzz" the pedal when you slam your brakes on.  You brakes would be allowed to lock up just like cars without ABS.

FWIW, my 76 Jeep did the same thing to me 3-4 times off and on for about 2 weeks.  Then I noticed the drips on the back of the passenger rear tire.  It didn't leak very much fluid at all each time, the reservoir looked full.  Then the next week, the pedal went all the way to the floor without stopping me =:-O. (at home, luckily at the bottom of the hill)  Had to have it towed to Midas.  Zero brakes.

Hope this helps,
SherryB