I’d check the brake booster vacuum line. What if there’s moisture in the line that freezes, blocking the vacuum supply to the brake booster? Then as the engine heats up it melts the ice in the line and the vacuum is restored to the brake booster?
Tester
Listen…if we were not on here making sure the America had safer cars we would have to sit down and listen to our wifes. (kidding)
OK, two things. One is we’re talking air temperatures of between -20 and -60, which means the air temperature around the brakes and lines at high speeds is going to be a lot lower than that.
This is physics 101…It’s called wind chill. It will NOT be colder. Wind chill is the rate of cool…not how cold something will get. If you have a glass of water sitting outside in 33 degrees and if there’s a wind that makes the Wind Chill 25 degrees the water will NOT freeze. The Temperature will still be 35 degrees.
I’d take as much of the brake components apart as I could . . and lube the moving parts with never-seize grease. Make sure it is OK with the rubber parts . . . and use it sparingly, a little goes a long way. Keep it off the pads and rotors, of course. Maybe the moving parts of the brakes are sticking or freezing. I also agree with the brake booster idea . . . maybe check it out for operation and proper vacuum. Good luck! Rocketman
Now you’re talking! I think maybe you’ve hit on the problem here. My Suby is a 1993. I’ll check with the dealership on this one. Thanks for the info!
Yeah, one mechanic suggested that may be the problem. But the Subaru mechanic said that wasn’t it, because if it was, it would have the opposite effect. He also said the brakes would be acting up in higher temperatures too if that was the problem. I might get a third opinion, though! Thanks for the suggestion.
My mechanic checked to see if there was a valve, and there isn’t. Good thought, though!
Well, seems like that is so, but just remember, up here every car is equipped with not only a block heater but an oil pan heater. If the oil is not heated at temps of under -20, it is too thick and the car will not start, literally. So, I have small trust in the idea that petroleum products don’t freeze at those temps!
Anyway, it does seem like there may be another factor involved, given the fact I hadn’t had trouble with this until my second winter with this car.
Hey, thanks for doing a little research! I’m appreciative.
No, they are still stiff, but just not totally hard.
That’s a thought. This car has only been in Alaska for two winters, but it’s old, so that might be something to check into. Thanks!
Sorry! I don’t have time for this during my work week so I have to wait until the weekend. Thanks for the responses.
Thanks, Rocketman. Any or all of the above may be factors in play, you’re right. I’ll see if I can get someone to test the booster at least.
Good thought! I wonder how you get moisture out of the line if it’s there?
Sorry for the slow response. I’m so booked during the week I have to wait for the weekend to do this. To answer your question, I have not had any work done on the vacuum system before this. The vacuum may be frozen, quite possibly.
The curious thing is that when I stand on the brakes and the car finally stops, I pull over and pump the brakes until they get a little softer and eventually they “let go” and function with some degree of normalcy, though still stiff. One time it wouldn’t release, and I had to just use brute force to push the pedal down. It worked and freed the brakes up, but I was told maybe that wasn’t a good idea, as I could break something on the brake pedal by doing that. Metal is apparently brittle at those temps. Still, when you’ve got to get your brakes working, you gotta do something!
Yup, you’re undoubtedly right. I was just repeating what my mechanic said. Still, we have to have oil pan heaters and block heaters up here, and if we don’t plug those in at severely cold temps, the oil literally does thicken and nearly freeze, to the point the car won’t start. I think most anything will freeze (except antifreeze), especially in small quantities, at these temps.
I have the same problem if the weather dips below 25 degrees C but if I let my 2002 Rav4 warm up for 10 minutes the brake problem goes away and the brake respond normally again. I think the problem has to do with the brake vacuum getting warmed up by the engine heat. There is someone who posted earlier about water getting into the brake booster vacuum line and they may be correct.
Finally, about 4 hours south of song catcher, we have a decent cold snap and my 2003 Subaru Legacy is acting very similar and has also affected my power steering. The brake scenario is constant, I start up the vehicle and allow it to have a comfortable cab temperature before my 74 mile commute from Willow to Denali State Park. Once I leave I always crawl to my gate as the first two or three brakings usually keep me rolling anyway which I believe to be frost related. Once on my side road the brakes function fairly well and should as most components were changed this last summer and a flush took place, not to mention a few rounds of bleeding. Once in the Hwy I only use my brakes for moose and it seems the further I travel the stiffer the pedal becomes. The cab temperature also decreases at higher speeds though the engine temperature is a constant. I have read through a few articles that agree DOT 3 has a working temperature to -40F. I do have a few friends on the slope who run equipment and if I hear of another fluid being used due to temperature, I will add it to this old but important post. Its a little hard to stop for a moose with frozen brakes and Subarus don’t fair so well with a 1400 pound moose. Under the same conditions, my power steering becomes tight as well. Tighter over longer distances… extreme cold must have an affect on these fluids! I notice some of these issues with a Toyota 4runner and would love to throw a Suburban in for comparison but it just won’t start when it is this cold.