Car Brake Pedal in warm weather

[dsteinmann]

Trying to find a answer to my issue, It only happens when the weather is around 75 or warmer my car wants to creep forward at a stop light So you have to use more pressure on the pedal. I have replaced the master cylinder, and checked the Brake vacum pump fuse. Im think it may have something to do with the fluid or something in the lines as its weather related, any thought im sure you guys will be more help then the cadillac forums, (many of them dont like to do any work their selfs)

 

[Coastiejoe]

What year what kind of Caddy?

Based on your fuse commet I take it you don't have the traditional vacuum booster on the fire wall but something like a hydro-boost. Is that correct?

If so, does it pick up power via a belt or only electronic?

 

[LouDoo]

I just happen to work at a Cadillac dealership, give me the year and model and I'll walk over and ask a Cadillac tech.

Lou

 

[dsteinmann]

its a 08 CTS, and yes it has the regular booster also but there is a fuse called "brake vacum pump"

 

[LouDoo]

O.K., I just went over and talked with our Service Manager, Steve Bentley, so this comes right from the top.

He said what probably happened is at one time the brake fluid peculated from the heat, he said he sees it here and we have very similar weather to St. Louis. Anyway he said when that happens it introduces air into the brake fluid and can cause the brakes to feel spongy. The cure is to flush and refill the system. He also said to use silicone brake fluid (DOT4) as it is less susceptible to boiling.

He also said in really hot climates like Florida and California they recommend flushing and filling the brake system at 20,000 to 25,000 mile intervals.

Lou

 

[dsteinmann]

Ok thanks ill try that

 

[Coastiejoe]

DOT 4 for sure.

Many place can "power flush" the brakes. This is the way to go as it will push the old fluid out of the master cylinder and through the lines. This will eliminate the old fluid as well ensure no air gets into the system.

 

[dsteinmann]

Ussualy always try to do it myself, I ordered a Mityvac pump to flush the system. And will replace with DOT4

 

[Hghgrad]

I was going to suggest the same. My explorer had a caliper bracket break, which locked the caliper against the rotor and generated a lot of heat in the very very short few seconds until I got it stopped. Replaced the pads/rotors. Didn't change. Had to flush the fluid, after that its normal again.