I have a 1990 accord ex

well i have a real big problem. whenever it gets warm, and i drive my car for a while the brakes are ALMOST not there. when it cools back down, they become fine, but when it is warm, i have to drive EXTREMELY carefully. the pedal will usually go all the way to the floor at the worst point. it will take a little bit for it to get this far.

i have heard that it could be either the power booster, or the brake master cylinder. I dont believe i have a bubble in the brake line, as this was happening at the end of last summer, just not as badly. i did flush the brake fluid last summer, and put in valvoline dot 5 fluid. maybe it wasnt dot 5, but it was supposed to outperform dot 3 by a significant amount.

has anybody else had this problem? know how to fix it?

 

It's most likely the master cylinder. Often times if the brake fluid hasn't been changed in a long time, and then you change it with all new clean fluid, the master cylinder will go out shortly after. Just like automatic transmissions. Same thing happened to mine last summer. I flushed out the brakes and the old fluid was BLACK (actually looked seawater green in the light, lol), and about a month later, although the brakes still worked fine, the pedal would slowly sink to the floor at stoplights and such. Also just like yours, it only did this when it was really hot out. At night when it was cooler, it would be fine. Replaced it with a reman'd MC, and it was a PITA!! Got a defective one and it made all 4 of my brakes lock up... it sucked! I also found out after the fact that reman'd MC's aren't very good, and I should buy new from Honda. So I'd go get one from Honda if I were you (assuming that's what it is). Once I got a good one though, brakes have worked great ever since, so that's all it was.

If the MC has leaked into the brake booster though, then that will probably need to be replaced too. That can be had at a junkyard for pretty cheap though.

 

hey thanks a bunch i will check that out later today