Brake fade in hot weather?!

[89AccordNate]

I dont understand why whenever it is really warm outside around 80-90 degrees and I am driving in the city traffic, my brakes fade to the point of almost the pedal going to the floor. If I release the pedal and push it again its a lot better..but still not right. I recently put a new caliper on my car, wonder if there is still air in the lines? It really makes me mad and it feels like I have NO brakes sometimes, while other times it is fine. If the weather outside is cool then I dont have this problem.

Any idea what it is?!

Nate.

[Mike89Accordcom]

You sure it's not raining out nate and your brakes are just really wet? I mean that's quite possible. You are the type of guy that drives through huge lakes in the road, btw that isn't good to do. You might be day dreaming there. Or maybe you just have worn brakes. Know what I mean jelly bean!

[smufguy]

like u guessed, its possibly air pockets in them. Did u put new brake fluid in them? It should be Dot 3 and nothing else, if i remember correctly.

[rocky2]

Your rear brakes need adjustment I'l bet.

[Jareds 89 LX-i]

Try bleeding the brakes again, and if it's still doing it then it's the master cylinder. Mine was doing the exact same thing, and only in hot weather also. I'd be sitting at a stoplight or something and the pedal would slowly go to the floor. Replaced master cylinder and it gave me a nice firm pedal with no more fade.

[89AccordNate]

Yea jared, thats what it does! But I guess it could be air in the lines. It was fine before I changed the caliper.....hopefully I dont lose my brakes .

Where is the master cylinder and how hard is that bad boy to replace?

Nate.

[smufguy]

its not hard to replace but its a bitch to get at. they are behind the dash so the dash needs to come off. they are held onto the pedal assembly by 4 12mm bolts which is a no big deal to remove. but like i said. its just a hassle. takes about half a day to get it done. u need to remove the brake lines WITH CAUTION NOT TO TWIST THEM. u will be out in like 4 hours max. Be sure u put EVERYTHING back together and not forget anything. And yeah, u need to fill em up with brake fluid once ur done.

[smufguy]

master cylinder is nothing but the big ass round shit with the filler on it. The filler is called the master cylinder??? i always thought the black thing was the master cylinder. anyways, the big black round shit attached to your brake fluid resevoir is the master cylinder. its a whole unit connected to the resevoir. just unbolt the brake lines from it. and how to take em out is in the upper post.

[RobT5580]

Both my cars have done that on very rare occation. I only notice it when its hot and i have the A/C on. My other accord has had a brand new Honda Master cylinder put in and all lines bled and if i remember it did it once or twice after that. My new accord did it a few times this summer. But on the other accord the master cylinder was bad because eventually they started to bleed out on a regular basis.

[DBMaster]

That was what mine did at about 93,000 miles and it was the M/C. It is just now starting to do it again so I am thinking it is getting close to needing another one (now at 198,000 miles)

Might just be coincidental with your changing the caliper, but it's easier to bleed the brakes than change out the M/C. Try that first. You'll end up having to bleed the brakes if you change the M/C, anyway.

Good luck with it.