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Very cold, NO BRAKES

21K views 40 replies 22 participants last post by  cbracquetball 
#1 ·
When it is REALLY cold out, like -10 below or colder my '02 Outback has NO brakes at start up. The pedal feels like a brick and stomping on it does NOTHING to slow the car down. After it has been running for about 30 seconds the brakes function normally.
It is not the loss of the power assist, the car has NO brakes. Anyone else have this problem, or an idea about what it may be?
 
#2 ·
Frozen pads, frozen rotors, reduced stopping power. Usually one or two normal stops are enough to liven them up. Also, if the ABS kicks in while the brakes are really cold, you are screwed.

I live on a court on the side of a hill, so when I'm leaving my house and the hill is slippery, I have to remember to turn up the hill rather than down it, because the combination of ABS + cold brakes will put me right through the stop sign at the bottom of the hill. I really gotta get around to pulling that fuse...

The Grabbers, on the other hand, will climb the hill at any temperature, unless it's skating ice.
 
#6 ·
I did NOT say I loose my power assist, I LOOSE MY BRAKES. NO STOP, PEDAL HARD AS A ROCK. I am 6'3" and 200 pounds, I can not stop the car with both feet on the brake. I have experienced the lack of power assist, this is alarming, but not unsafe.
Sometimes I hear the ABS cycling, other times I do not. When it is well below zero the brakes DO NOT WORK for about 30 seconds after start up.
 
#8 ·
DAS said:
I did NOT say I loose my power assist, I LOOSE MY BRAKES. NO STOP, PEDAL HARD AS A ROCK. I am 6'3" and 200 pounds, I can not stop the car with both feet on the brake. I have experienced the lack of power assist, this is alarming, but not unsafe.
Sometimes I hear the ABS cycling, other times I do not. When it is well below zero the brakes DO NOT WORK for about 30 seconds after start up.
So then why are you driving the car and not taken it to the shop. Let the car sit over night at the shop and get a cold soak.

Also there is a recall for this issue, I do not remember what year is covered.
You may also have water in your brake lines.


You will have to look it up.

nipper
 
#9 ·
The problem only occurs when it is at least -10, and it is gone in about 30 seconds. That is not a very long window of opportunity to test for problems. I have no faith in my local dealer, and have no relationship with any garages, as I have always done all my own mantenance myself.
When I leave my house I start the car in the garage. My driveway is very steep and down hill from the garage. On cold mornings I test the brakes before decending the driveway. The last time I had a problem I had left the car in a commuter parking lot. When I returned it was -15. I started the car and tried to back out of the parking space. NO BRAKES. Hitting the pedal with all I had there was no way to stop the car. I put it in park and pumped the brakes until they worked. The pedal was very hard for about 30 seconds, then normal. The car is an '02 LL Bean.
I really think it is something in the ABS system. Sometimes the pedal vibrates and bangs as if I were skidding on ice, but I am not. The ABS light has never come on.
I don't understand why the brakes function normally after a moment. There is not enough time for engine heat to have any effect. Maybe the problem goes away when the ABS pump cycles?
 
#10 ·
DAS said:
I did NOT say I loose my power assist, I LOOSE MY BRAKES. NO STOP, PEDAL HARD AS A ROCK. I am 6'3" and 200 pounds, I can not stop the car with both feet on the brake. I have experienced the lack of power assist, this is alarming, but not unsafe.
Sometimes I hear the ABS cycling, other times I do not. When it is well below zero the brakes DO NOT WORK for about 30 seconds after start up.
When there is no power assist (the vacuum is all gone in your booster), you will have a rock hard pedal. I just experienced this for the first time recently and my experience sounds like yours. It is the check valve in the brake booster line. Moisture in the valve freezes and causes the valve to stick.

You'll probably have a regular pedal when you first step on the pedal to shift from park. This is using up some of the reserve vacuum in the booster (this is the function of the check valve - to keep a reserve of vacuum in the booster should the engine fail while you're in motion - the reserve of vacuum will be enough to have power brakes for one or two pumps of the pedal). In fact, when I pulled my hose to spray wd-40 down it, there was a hiss as the reserve vacuum was lost from the booster.

The second or third time you step on the pedal you will have no power assist and a rock hard pedal. I'm guessing that after a bit of warm air gets in the vacuum hose, the valve loosens (or maybe the force of mashing on the pedal causes it to break free or maybe the build up of vacuum between the engine and the check valve causes it to free up) and you have regular brakes again.

When I had the booster hose off, I blew into it from both ends, and can confirm that there is a check valve in there and mine was working, but it was warm at the time. I was tempted to throw it in the freezer for several hours and see if it would stick.

The next time it's that cold out you can figure out if it's the check valve. Start your car. Step on the brakes - pedal feels normal? Step on the brake again - pedal is rock hard - it's the check valve.
 
#12 ·
Garth said:
as I have stated before...my 01 does it warm and COLD....
Maybe you just have a plain old defective check valve, or some other problem. A new hose is cheap, and will have a new check valve in it. I have a new one ordered and it cost $25 CDN. Since Subaru Canada royally reams us on prices up here compared to the U.S., you'll probably pay $12 or something.

Replacing it is simple. Have you tried this option?
 
#14 ·
I experience the same thing on cold days. When I know it's going to get very cold overnight, after I shut the car off, I pump the brakes until there isn't any play left. This (I think) eliminates air or whatever in the lines to freeze so when I start the car up in the morning, one pump of the brakes before moving gets them back to normal.
 
#15 ·
First post on the forum.

I have this exact same problem on a '02 LL Bean. It's my wife's daily driver so I've only experienced it a couple of times, but she says it's been happening every morning since it's gotten cold. It only needs to be in the teens to make it happen (not super cold like -10). We just bought the car over the summer so this is our first winter with it.

DAS, did you ever resolve your issue? What was it in the end?

I've read the thread about the power brake issue and it definitely could be that, although again, I haven't experienced it enough to assess whether there are NO BRAKES, or whether it just brakes really hard. They always come back within 30 seconds or so.

I'll be taking this into my mechanic in the next couple of weeks, but I thought I'd check in here for opinions since so many others seem to be experiencing the issue. Thanks in advance for any additional thoughts.
 
#16 ·
Nope. Still an issue. I had not experienced it in quite a while,then it happened again just yesterday. Parked at work all day. I started it up, left the parking lot and approached a stopsign at at t intersection. I was not gong too fast. I went to stop, and no brakes. I almost broadsided a dodge caravan. It was 16 degrees out. I don't ever remember it happening while this "warm" out. I have put 196,000 miles on the car, and it has been an issue since day one.
After this the brakes were fine. It is just that first use when it is cold out.
 
#17 ·
Oh man, that sucks! Is it fair to say that you've tried to solve this to no avail? Should I even expect my mechanic to find something wrong? I really need to solve it because my wife drives our 2-year old son around in this car...

I saw that you're also in VT, so it's at least good news that you still have the car. I was slightly worried you were going to reply with, "Nope, we sold the car this past summer in Montpelier, and it was white with 55k". :gasp: :D
 
#18 ·
It is water in the vacuum line from the manifold to the brake booster, freezing in the check valve.

You can remove the hose when warm, and flush thru with some WD-40 and clean the water out of there. Then re-install the hose and you should be good for a while until you get significant water in there again. Pay attention to which end goes where....

On the really cold days, I always pump my brakes a few times before moving into Drive, to ensure that the valve is free. If it is sticking, and I get the rock hard pedal, a few more pumps is enough to free up the valve and return normal brake function. I learned the trick the hard way, almost rolling thru a busy intersection because I didn't check first. Some times you really have to stand on it, but you can free it up thru pumping the pedal.
 
#19 ·
OK, thank you!! Good to know. I will check that out and do the WD-40 thing. Give me a couple/few weeks and I'll report back with results.

Regarding the bit about "should be good for a while until you get significant water in there again", is there something else wrong given that water gets in there AT ALL? Or does that just happen with the Outbacks? Is there anything I can do to prevent water from getting in there again?
 
#22 ·
The water isn't in the brake fluid, it's in the vacuum hose for power assist. It's not clear to me how it gets in there, but these are pretty high mileage cars.
 
#24 ·
This happened to me only once, it seems to be a definite temp/humidity combo that creates it.

If someone is seeing it regularly an interesting diagnostic would be to shut the car off then pump the brakes to drain the vacuum, then see if the problem occurs in the morning.
 
#26 ·
Its really simple. Iced check valve will not allow vacuum on the booster which equals hard pedal due to not having any assist from the booster. After the engine warms up, the heat generated by the engine melts the ice in the check valve and allows the engine to pull a vacuum on the booster easing the pedal effort.

Water in the brake system can cause high pressure on the brakes. Especially at negative F temps. With the heater running in the car, it would assist in thawing some of the lines. Its more likely a brake booster issue or a frozen check valve. If the car has a check valve. Some don't.

If there is a tear in the booster diaphram, it can pull in moisture.
 
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