Did You Know That Your Car's Brake Fluid Can Sometimes Boil?

Posted on: 6 April 2022

When your vehicle's engine is operating at peak performance, temperatures inside the block can get very hot indeed. This is why you need an efficient cooling system so that you don't run into problems in the future and end up with an expensive repair bill. But, did you know that your braking system can get very hot as well and that if you're not careful, problems can arise here? Why does this system heat up so much, and what are the tell-tale signs of an issue?

Heat Buildup

Most modern vehicles have rotary brake discs on each corner, as this is thought to be the most efficient retardation system. When you put your foot on the brake pedal, hydraulic fluid will be pumped through pipes to each corner and into a set of calipers. When it does so, it will activate pistons that push a pair of brake pads against the rotary disc to slow it down. The brake pads are made from a friction material that will automatically degrade as contact takes place, but as with anything involving friction, high temperatures are not far behind.

Significant Temperatures

It is not unusual for your brake discs to heat up significantly, especially if you are in stop-start traffic or driving in hilly territory. The discs themselves are designed to cope with excessive heat, but these temperatures will inevitably transmit back through the system and heat up the supplying pipes.

Hygroscopic Fluid

Hydraulic brake fluid is carefully designed so that it can cope with very high temperatures without boiling, but occasionally, issues can arise. This is because brake fluid is hygroscopic, which means that it can absorb water. While the entire system is meant to be sealed to avoid any moisture infiltration, it can sometimes happen anyway, as tiny particles can get through joints and connections or penetrate rubber pipes. Some water can also get into the system through the brake fluid filler cap if it is not attached correctly.

Compressible Moisture

As any particles of moisture will have a significantly lower boiling point than the brake fluid itself, this can compromise the operation. While the brake fluid is not compressible under braking, the water is. You may find that it takes a lot more effort to slow the vehicle down, and in some circumstances, the brake pedal can even go straight down to the floor.

What You Should Do

So, to avoid this situation happening in the first place, make sure that you always attend a scheduled service for brake repairs. The mechanic will have a look at the efficiency of the brake fluid and, if necessary, change it.