Why do my brakes lockup when it's cold? (Can't push pedal down)
 

Hey all :)

Lately it's been pretty damn cold... in the morning when i start the car, and wait about 20 seconds, I pump the brakes about 5 times, at which point the pumping distance gets shorter and shorter until i can no longer push the brake pedal down.

I wait about a minute and try again, finally it's free and i can brake normally.

Obviously this is caused by the cold weather. But, what should i do to correct this? change the fluid? is it caused by air in the lines? or...

any help would be great! :) thanks.

Sounds like you have a vacuum leak at your brake booster. At first I thought you have water in your brake lines and they are frozen, but it would not cause the symptoms you describe. I would check all vacuum brake booster lines and make sure there are no leaks.

a stuck compensation port?

I agree with Eric, BUT why are you pumping it so much in the first place? :gotme: A cold engine may not have enough manifold vacuume to recover quick enough. 5 rapid pumps may deplete the booster quicky.

that's what i was thinking too... i figured the engine is super cold still
so me pumping my brakes might not be helping the situation.

But, the reason why i'm now doing this is cause one morning (before pumping brakes in the morning...) I took off for work, and on the 3rd stop sign, my brakes were non functional... simply stuck as described above :( I used my hand brake and came to a stop. Pulled to the side and pushed on my brake a little and waited another minute... it let out and never gave me the problem again that day. Thats why before leaving for work now, i pump the brakes until they lock up once. then when they release, i take off. They never lock up after that.

This only happens when it's REALLY cold out... as of lately it's been pretty nipply outside... :(

That sound very strange. I can pump my brakes all day long and not have a problem. I think you need to check out you booster, or the compensator valve like nismo said. that is definatly something you need to check out.

There's a check valve I think.. between the manifold and the brake booster. Perhaps it's not functioning correctly or is clogged? :gotme: Or as Eric said the booster may have a leak.

yes there is one, just remove it from the hose and try putting one side in your mouth and blow. you should only be able to blow out through one way so if its stuck or you can blow out through both ends then you need to fix that. Make shure you pay attention to which way the arrow points when you put it back on.

hmmm yikes, hopefully this wont be an expensive problem....
can't i just live somewhere where it's warm all year.... :(

I'm gonna check this out this weekend.

I'm also assuming that if i let this go too long i might end up without brakes while trying to stop quickly sometime...

thanks :D