Anybody else's brakes "freeze?"

[filter27e]

When it drops below freezing my brakes seem to freeze up when I first start my car. If it's not that cold out (20's) than I usually can just push on the pedal a few times and it goes back to normal, but if it's really cold out like single digits then it takes forever to get them to unstick. If I just try to drive without doing it then it will stop but it's like driving without a booster. It did it last winter and I've changed my fluid since then but I suppose it's possible it could be the fluid again, last time I bled my lines I used fresh fluid from a bottle that wasn't sealed, but I wouldn't think it would make it that bad. Does this happen to anybody else?

[StatGSR]

yea happens to me, little scary too, but its usually only one stop with what feels like mechanical brakes then it seems to go back to normal.

[Huffer]

The cold does delay the brake feel somewhat. Just start out slow (as you should) and the pedal feel will come back.

If there is water/moisture/air in the lines it will freeze.

[rougeben83]

I got that yesterday, coming out of the carwash in 20-something degree weather. I think some water froze on the rotors so I had the pedal to the floor-but-no-stopping-feeling for a minute or two...

[filter27e]

Nah mine's not like it goes to the floor and does nothing, it's more like the pedal is stuck and feels rock solid. I don't think it's fluid because it doesn't do it if I warm my car up for 15 minutes or so, like it's in the booster or something next to the engine.

[Sarra]

Anyone know the freezing point of DOT brake fluid?

[Perdue]

Sure you don't have water in your brake lines?? They can draw moisture from the air over time, which I assume could freeze in the same sense that it could change to a gas once hot enough under braking, and make for a soft pedal. IIRC, you should bleed'em every 15k or 30k.

[GT Wagon]

Anyone know the freezing point of DOT brake fluid?


Waaaaaaaaay below the temperature at which you'll die. It gets cold as well Hell in Canada during winter. We'll hit -35 on cold snaps for a few days. I think you have something wrong with your brakes because while everythign gets stiffer in the cold, I've never lost my brakes by any means even in the coldest of mornings.

[Sarra]

Anyone know the freezing point of DOT brake fluid?


Waaaaaaaaay below the temperature at which you'll die. It gets cold as well Hell in Canada during winter. We'll hit -35 on cold snaps for a few days. I think you have something wrong with your brakes because while everythign gets stiffer in the cold, I've never lost my brakes by any means even in the coldest of mornings.

-35c or -35f? I know places near here that sometimes get to -90f during the winter, usually about -80f with another -10f from windchill. :p

I had my brakes freeze on me, I was driving very fast through slush and the ambient temp was just dipping below freezing. I got lots of semi-frozen water on the brake rotors, so when I pressed the brake, nothing happened for a moment. Then it melted, and my brakes were just fine.

[jeremod]

The problem is something with the brake booster or the vaccum system. The car will still stop ok but you have to stand on the pedals. This is apparently a fairly common problem with older legacys and outbacks. My mechanic told me he's had a few cars do this. My 96 would always do it when it was colder than about 20*F until I ran SeaFoam through the brake booster line. It hasn't done it since. I think there is a check valve somewhere in the brake booster system that keeps the booster working for one or two stops after you shut off the engine. My theory is that this check valve gets stuck closed so no vaccum gets to the booster until the car warms up a bit.

When I had the problem the brakes would work when I first got in the car and drove away but the next time I hit the brakes the pedal would feel like a rock. It was something I came to expect when it was cold and could live with.

Try running some SeaFoam through the booster line and see if that helps.

[TRUBLU]

I think there is a check valve somewhere in the brake booster system that keeps the booster working for one or two stops after you shut off the engine. My theory is that this check valve gets stuck closed so no vaccum gets to the booster until the car warms up a bit.


This is EXACTLY the issue which explains why flushing the fluid didn't help.

I've seen these threads so many times. I replaced mine yesterday.