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Hey guys figured you may know the answer to this... Whenever its really cold, and I drive away without letting my car heat up for 10 minutes, ill hit my brakes and nothing will happen. Its really scary when it happens and I have had to hit the hand brake multiple times to avoid accidents. It only happens when its super cold outside and when my car is cold. Any ideas to fix this? Do I need to bleed my brakes and do new fluid? Also what type of pads should I get? Has anyone noticed a difference between organic and ceramic on the oem rotors?

Thanks for the help,,

maybe you have water in the line and its freezing up. id drain/flush the system and put new fluid in. wouldnt hurt to check your pads while your at it.

I guess I have a couple questions....when you say you hit the brakes and nothing happens, can you elaborate? Does the brake pedal go to the floor? Does the brake pedal feel the same, but the brakes just don't work? Does the brake pedal feel stiff?

How cold does it have to be for this to occur? At freezing (32 deg F) below freezing?

Even if you have "race" pads that don't work well when cold, they should still provide "some" braking. If you're getting nothing I'd suspect you may have water in your brake lines or the calipers are frozen.

Does this occur when it is dry outside or when it's snowy/wet roads?

Organic pads will be better at cold braking and dust less, however do not have very good high temp braking. Most performance pads are a combination of ceramic & metallic and have good low temp performance with decent high temp fade resistance.

What type of pads are you currently running?

Is it possible that your brakes are actually working, but that the power assist isn't working?

There's a check valve in the vacuum hose that goes from the brake booster to the intake manifold. Sometimes if there's moisture in it, it'll freeze when it's cold and you loose brake boost. When the engine bay warms up, the ice in the check valve melts and the brakes work right again.

If this is what's happening, an easy fix that tends to last for a while is to pull the hose off the brake booster and intake manifold and spray some WD-40 into the check valve from both sides. That'll keep water from sticking to the valve.

Some antifreeze or heet type stuff would also probably work.

Thanks for all the quick replys... Basically when I hit the brakes, they go stiff and the pedal does not go down as far as it should.. But once the car is warm its fine. I think I may just flush my system and get some new pads and see if that works...

celliot89 wrote:Basically when I hit the brakes, they go stiff and the pedal does not go down as far as it should.

That sounds a lot like the brake booster check valve problem. Just sayin'.

Legacy777 wrote:Some antifreeze or heet type stuff would also probably work.

Yes, HEET (which is basically methanol or isopropanol) will unfreeze it. Then WD-40 will keep water from condensing onto it in the future.

I agree with Vikash, sounds like moisture in the vacuum assist line check valve.

Man up here in northern canada it seems like every winter I get this whenever it goes to -30. I just take the brake assist line off, bring it indoors over night and the next morning brake clean the hell out of it and blow it with an air nozzle. Ussually works but I have replaced it once too.

Does the moisture / condensation get inside the hose due to a bad brake booster ? I can only imagine if there were water or moisture in the line the engine vacuum should draw this moisture / condensation in toward the engine. This has never happened to me in years past. I just experienced this for the first time this morning; and I've owned the car since 2006. Every winter temps drop well below freezing where I live. I'm wondering, does replacing the valve stop the reoccurrence of the valve freezing ? Or do additional parts need to be replaced to stop the excessive moisture from entering the hose to deteriorate the valve and allow it to freeze ?

http://my.cardone.com/techdocs/PT%2053-0002.pdf

Although this bulletin is for newer Subaru's, it's the same situation.

If the booster had a leak you would know it because you wouldn't have good brake assist all the time...so I don't think your booster is bad.

Moisture can get in the line from the intake manifold and PCV lines. A bunch of short trips may create excess moisture in the crankcase which could cause more moisture to be drawn into the intake and into the brake booster check valve.

If you haven't done a long trip in a while, you could try that to get the engine and all the moisture out of the oil. Then you could bring the brake booster hose inside to warm and thaw out. You could use a hair dryer to heat up the valve and try to get all the moisture out.

Two weeks ago I made a 6 hour round trip. It was a one shot, there and back trip to a boneyard 180 miles away to pick up car parts. I'm going to try the WD-40. I just find it strange that it has never done it in the 5 winters previous.

I too live in Canada and its can get pretty cold here. Last Tuesday it got down to -7°F. That will freeze up the brake booster and make the pedal feel like you have no brakes. I just pump it a few times before I move the car to free it up. I also start the car on the coldest days and let it warm up a min or so before driving.

I just thawed out a frozen back door on my outback yesterday

diesel devil wrote:I too live in Canada and its can get pretty cold here. Last Tuesday it got down to -7°F. That will freeze up the brake booster and make the pedal feel like you have no brakes. I just pump it a few times before I move the car to free it up. I also start the car on the coldest days and let it warm up a min or so before driving.

I just thawed out a frozen back door on my outback yesterday

So, is it to be considered normal characteristic - no fix ?

UPDATE: I'm very happy with the end results of saturating my valve in both WD-40 and HEET.

Good deal!