I have a 94 civic dx, auto with 150k on it. Everytime it gets warm, and im sitting still, (like at a red light or stop sign, anytime the brake must be applied for a extended period of time) the petal will slowly start to go down to the floor board until eventually it bottoms out on the floor board. Im not real sure why it does this, it only happens when its hot. In the mornings on the way to work it doesnt do it. I check the level of my fluid often and the level hasnt when down at all so im pretty sure I dont have a hole in any brake lines or any leaks. so im thinking I may need to bleed all the brake fluid out and put fresh in, or is it something with the brake master cylinder like a seal?

 

Bleeding won't hurt, but it sounds like an internal master cylinder leak to me.

 

can i get like a seal kit for the master cylinder or do I have to buy a completely new master cylinder?

 

is this a rebuild kit? http://www.rockauto.com/catalog/moreinfo.php?pk=310246

 

I haven't tried it myself, but a rebuild seems worth a try if it's much less expensive than replacing the MC. Post pictures of the rebuild if you can.

 

Master cylinder seal seems bad too me. You can actually rebuild the master or buy a rebuilt one.

I rebuild one at school, not too hard.

 

I just got a used one that is a nissin reman that was only 6 months old off a totaled 93 dx for $25 so im going to try it out. A rebuild kit is around $35 shipped but it didnt look to hard to do. Thanks for everyones help