It seems that when the inside/outside temperature of the car gets above 80 degrees the brake start to go to the floor. When I sit at a light, I feel the pressure in the brake pedal soften and the pedal goes to the floor thus forcing me to pump the brakes. I've checked the fluid levels which is at the proper level. Does anyone have any ideas? Is there a relay for the brake system that may be going bad?

 

sounds like the master cylinder is letting go..

 

Agreed. Usually when the MC stats to go it will give you the pedal drop if you are lucky. Unlucky your pedal just falls to the floor while going down hill :eek:

Have you ever changed your brake fluid? Flushed the system? Maintenance of the brakes includes flushing/bleeding. Not just pad changes, rotor resurfacing.

 

I know I've awoken an old thread. But i guess its better to wake one up then to open a new and hear the ol' why don't you try searching first.

When it was over 90 degrees in my state this past summer. I had a squishy pedal. It wouldn't just fall right to the floor. I had a little pressure but not much. My car would stop. But it would also slowly keep falling down to the floor. A brand new master cylinder was put on the car when i got it. When it wasn't as hot out it wasn't as squishy. If at all. Could this be as simple as air in the lines? Or how big does a brake line leak have to be to have an effect like that? I have a theory, that if i have a VERY small leak. When it is very hot out, the brake fluid itself is a thinner consistency. Which would cause air to leak into the lines. I am going to flush and bleed the lines but if i have a small leak in the lines some place then id like to fix that first.
I guess my question is if i have a leak would i for sure know it? Ive looked around and haven't seen any dripping or pouring out. No puddles on my garage floor either. If there is one it is REALLY REALLY small. Everything I've read people lean towards the MC. It makes me think the guy had to have put it on for a reason. But i have no way of contacting him and now my pedal is squishy when its hot outside. Any and all help is appreciated! Thanks.

 

aftermarket reman mc's can be bad