Brakes suddenly applied while driving!

[twoseids]

If you can explain this problem, you are a god!

Recently, while driving, the brake pedal made a popping sound and actually rose maybe a half inch or an inch. At the same time, the brakes were applied - not all-out, slamming brakes, but as if I were pushing the pedal halfway down. If I pumped the brakes a few times, they would relax, but then 5-10 seconds later the problem would reoccur.

I took the car to the nearest workshop (quality or trustworthiness not guaranteed!), where they replaced the "brakes master pump" and the back brake pads. Cost me about $90 (I live in Malaysia). Within a day, the problem resurfaced, so I brought it back to the same place. They replaced another kind of pump (on the receipt it looks like "body pump" but I'm not sure). Cost me another $50.

It's been fine for 6 weeks but just happened again today. I can't, for the life of me, figure out why the brake pedal goes UP when the brakes are suddenly applied. The only thing I can think may be a factor is that I used to use a security lock which was like a hook, applied to the steering wheel and brake pedal rod. Maybe the pulling pressure on the lock, over time, did something?

Anyway, like I said, if you can explain this, I'll be forever in your debt and will proclaim your status as a car god to everyone I know.

[16th hippy]

ok, for some reason it sounds like water contamination(or other liquid besides brake fuild) mixed in somewhere with the brake fluid. In a was it explains the pedal coming up...not alot, but is possible. definately explains the self application of the brakes. Realize you post is old, but was wondering if you ever found out the problem.