It is no surprise to anyone who lives in a cold climate that early mornings and cold weather are not a good combination for a car. Issues that do not hinder your car in warm weather, can make it difficult for a frostbitten car to start. And what about the brake system
Can brake lines freeze?
The answer is sort of. Brake lines do not freeze the way water freezes. They are filled with brake fluid, which can congeal at temperatures lower than -40F, as long as it is not contaminated, but they do not freeze solid.
But this isn’t the whole story. If brake lines only froze at temperatures lower than -40F, it would be an uncommon occurrence. But people report their brake lines freezing more often than you would think. Let me explain.
How Brake Lines Freeze
The freezing point of brake fluid is -40F, but this temperature will not turn your brake lines into icicles. Instead, the brake fluid will begin to congeal. Congealing isn’t much better than freezing. If your brake fluid congeals, you won’t be able to use your brakes.
This is not a problem for most of us as these temperatures are not all that common.
But there is a hitch. Your brakes lines can freeze at higher temperatures if they have not been serviced regularly.
Brake fluid is hygroscopic which means that it absorbs moisture from the air. Even though the brake system is mostly airtight, the brake fluid still comes in contact with some air and moisture in the brake fluid reservoir. Over time the shifting of connections and valves can also allow moisture into the system.
When there is water in the brake lines, they will freeze at a higher temperature as the freezing point of water is 32F, significantly higher than the freezing point of brake fluid.
And an alarming 20% of vehicles have brake fluid in their brake lines that is at least 5% water. (Source) This water contaminated brake fluid will cause the brakes to operate inefficiently. It will also lower the boiling point of the brake fluid and raise the freezing point.
It is unsettling to think that 20% of people driving around with brakes that are likely not functioning as they should!
It is hard to know exactly what temperature the brake lines will freeze at. It depends on the quantity of water in the line. The less water you have in your brake line, the lower the temperature will have to be to cause a brake problem.
It is recommended that you have your brake lines flushed every 2 years to prevent this kind of contamination, and to have your brakes inspected every time you have your oil changed.
This is especially true if you live in a region with cold, harsh winters. You will want your brake system to be in tip-top shape when you have to drive in snow or icy conditions.
The brake lines on tractor trailers can freeze as well, but the culprit is not water in the brake fluid, but water in the brake lines of the air brakes. The result is the same – brakes that don’t work.
Will All Types of Brake Fluid Freeze?
There are three different kinds of brake fluid: DOT 3, DOT 4, and DOT 5.
DOT 3 an DOT 4 are glycol-based fluids which means they can absorb water. DOT 3 and DOT 4 will congeal at -40F, but if they are contaminated with water, that temperature does not need to dip down that low.
DOT 5 is a silicone based brake fluid which does not absorb water, and this makes a big difference. Its freezing point is still about -40F, but since it does not absorb moisture from the air, its freezing point does not fluctuate.
You may be wondering why all cars don’t use DOT 5 then? It would mean fewer fluid changes and fewer brake failures.
There is one problem with DOT 5. It doesn’t work well with anti-lock brake systems, and anti-lock brakes are very effective in helping you stay in control of your car when it begins to skid.
DOT 5 is frequently used for tractors and antique cars.
What to Do if Your Brakes Seem Frozen
- Try to start your car. This may be more difficult than it seems. If the temperatures have been cold enough to freeze your brake lines, then it is likely cold enough to cause other areas of your car, like your battery and carburetor, to stop working as they normally would.
- Warm up the car and see if your brake pedal starts working, while your car is still parked.
- If your brakes start working, that is great, but it also means your brake lines need to be serviced. Don’t put it off! Get your brakes serviced right away.
- If the brake pedal still does not work, even after the car has been warmed up, then you might have another problem.
How to Prevent Brake Lines from Freezing
Regular maintenance of your brake system will help keep your brake lines free of water and will keep your brake system working properly.
Avoid opening your brake fluid reservoir unless you must. Frequently opening your brake fluid reservoir will allow the brake fluid to draw more water from the air into the brake lines.
If you happen to live in an area where the temperatures dip lower than -40F (believe it or not, they do exist!), there isn’t much you can do to prevent your brake line from freezing. Although if the temperatures are that low, travel is likely dangerous anyway, and you should probably stay off the roads if at all possible.
Frozen Brake Lines Might Not Be the Problem
You may be thinking that your brake lines are frozen when in fact something else is going on. The brakes can stop working for a number of reasons, but I will outline some brake problems that occur specifically in cold weather.
Inconsistent Brake Booster:
The brake booster is the part of the brake system that allows you to lightly tap your brake pedal and have the brake system respond. For many people, braking would be nearly impossible without the brake booster.
Like the brake pads, the brake booster can accumulate water and debris. If this freezes in certain locations, it can cause you to lose the vacuum in your brake booster, and the brake booster will stop working.
When you heat the car up, the brake booster will suddenly begin working again, but it is time to have it checked out and maybe some parts replaced.
Ice Build Up Around Caliper
Driving home in a snowstorm is one of the most nerve-wracking experiences you can have on the road, but driving through high snow accumulations can cause more trouble than white knuckle driving.
If snow works its way into the wheel and lodges itself around the caliper and then freezes there, your brakes will stop working because the caliper will be unable to press the brake pad against the brake disc.
The only way to fix this is to get a heat source close to your wheels. If you have a heated garage, this will not be a problem. If you don’t, then you might need to get creative.
Damaged Brake Pads:
Winter driving conditions require more braking and slower travel. Wet brake pads require you to press the pedal more firmly because they offer less friction compared to dry ones. This causes the brake pads to wear down more rapidly.
But that isn’t the only way winter weather can damage brake pads. Water and road salt can get into tiny cracks that form in the brake pad. As the water freezes, it expands, causing wider cracks.