i *think* mine is failing. any sure fire way to test it out???

I *think* I have an ever so slight fluid leak because the brake light randomly will flash on tight corners and stops / take offs. The pedal also slowly sinks all the way to the floor if i keep it pressed. Granted, the car stops every time, but the pedal is spongy and if i pump it, it firms right up.

I also have a vac / boost leak that gets fixed tomorrow, and i did notice that when i turn the heat on, the brake pedal firms up a bit (no clue as to why).

any clues? does that sound like a master cylinder or a brake booster? would a vac leak cause any problems?

 

Frompersonal experience with a failed master cylinder on the TT your problem sounds like the master brake cylinder.
My master cylinder wnt out on me and the pedal would go down to the floor if I kept it pressed. As well as by pumping on the pedal it would firm up.

I took it into a brake store because I didnt think I could do the replacement, I would of after reading some of these DIY's online.

The brake shop charge me about $400 way too much.
I would recommend replacing it yourself if the master brake cylinder is infact the problem.

 

im not really sure what is broken at this pt. we bled the lines and that didnt seem to solve it. any other ideas?

 

Check the vac line to the brakes. It is a crappy plastic that can break. Also check the lines if you cant find the leak of brake fluid.

 

we're thinking that this happened when we did my break job and compressed the caliper. is the vac line to the brakes in any of the diagrams so i know where i am looking or do you mean the actual brake lines to each brake?

i also have that ripped open hose right below my intake manifold. i wonder i that comes into play at all... i mean i could see a vac leak making things spongy, but i have to be leaking fluid somewhere.

 

FAQ has the diagram. It is the hose at the end of the intake manifold.

 

Thats a classic secondary seal leak in the master cylinder, or your leaking brake fluid. If you brake booster was bad or had a bad vaccum leak the brake pedal would be hard as a rock. Not to mention if would be running lean and the engine would try to stall if the leak was bad enough.