When you press the brake pedals, brake fluid produces hydraulic pressure, which stops the car’s front and rear wheels. Brake fluid also absorbs heat generated due to friction between the brake pads and the brake disc.
You might wonder if the brake fluid might catch fire if it gets too heated. So, in short, yes, brake fluid is flammable. Modern brake fluids are based on glycol-ether, which is a flammable chemical.
Although it is unlikely that your brake fluid will catch fire without an external ignition source. Let us go through Is Brake Fluid Flammable? in detail.
- 1 What Happens to Brake Fluid When It Gets Hot?
- 2 What Temperature Makes Brake Fluid Flammable?
- 3 Is Brake Fluid Dot 3 Flammable?
- 4 Is Dot4 Brake Fluid Flammable?
- 5 FAQs (Is Brake Fluid Flammable?)
- 6 Conclusion
What Happens to Brake Fluid When It Gets Hot?
When driving in a city, on short journeys, or downhill, you will need to use more brakes. As a result, brake fluid can get quite heated when the brakes are used often. Here are a few symptoms that your brake fluid is too hot:
- The brake will feel mushy and unresponsive if the fluid becomes too hot or boils.
- Burning smell when applying the brakes.
- Smoke is coming from the brakes.
Brake fluid can boil in the braking system at high temperatures, but there is a meager chance that it will ignite. This is due to the brake fluid’s high autoignition and flashpoint temperature.
Also Read: Is Transmission Fluid Flammable?
What Temperature Makes Brake Fluid Flammable?
The flashpoint of braking fluid is between 210 and 375 degrees Fahrenheit, whereas the autoignition temperature is between 540 and 675 degrees Fahrenheit. A flashpoint is a minimum point at which a fluid can catch fire when ignited by any external source, whereas autoignition is the minimum temperature at which a liquid will catch fire by itself.
It is unlikely that brake fluid will be subjected to such high temperatures under normal driving circumstances. Some examples of how brake fluid might start a fire are:
- In an accident, brake fluid may spill over a hot engine exhaust or any other part.
- Brake fluid is spilled on a hot engine part when filling the brake fluid reservoir.
- Using the brakes repeatedly or for lengthy periods might cause them to overheat. This can happen when driving downhill. The fire risk increases when the temperature rises between 540 and 675 degrees Fahrenheit.
Also Read: Is Engine/Motor Oil Flammable?
Is Brake Fluid Dot 3 Flammable?
Yes, the DOT-3 brake fluid is combustible. DOT 3 has a flashpoint of 230°F, which is relatively low and comes into contact with a hot surface. Dot 3 brake fluid has a flammability rating of 1, implying that it is usually not flammable but can turn hazardous at high temperatures.
Is Dot4 Brake Fluid Flammable?
Both DOT 4 and DOT 3 braking fluids are glycol-ether-based. When exposed to high temperatures, both brake fluids are flammable. The flashpoint of DOT 4 brake fluid is between 210 and 375 °F.
Because of its high boiling point, DOT 4 is considered safer at high temperatures. If you’re seeking a less flammable fluid, DOT 5 brake fluid is recommended. Because it is silicon-based, it has a high flashpoint, which makes it less flammable.
FAQs (Is Brake Fluid Flammable?)
When brake fluid becomes too hot, it boils, and water becomes steam. If your brakes are extremely hot, they can take up to 20 minutes to cool down. You can reduce the car's speed; at low speeds, there will be less need to apply the brake. By doing this, the brakes may cool down more quickly.
Brake fluid can ignite if it comes in contact with any spark. Brake fluid has a flash point between 210 and 375 °F. Ensure the brake fluid is not exposed to the hot engine surface or any ignition source.
It is not advisable to pour brake fluid when the engine is hot. This is due to the possibility of brake fluid spilling onto hot engine parts. Because brake fluid is combustible, it can cause serious problems with the engine. Allow the vehicle to cool for a few minutes before adding the brake fluid.
If the brakes become too hot, the brake fluid might boil. The brake might become spongy and unresponsive as a result of this. It can also produce steam and emit a burning odor.
To perform efficiently, brake fluid should be no hotter than its boiling point. The wet boiling point of the braking fluid is 446 degrees. Fahrenheit; the boiling point after absorbing moisture can be as low as 311 degrees Fahrenheit.
To summarize, yes, brake fluid is flammable. However, brake fluid does not burn efficiently. This is because it has a high autoignition temperature. The brake fluid in the braking system may boil and convert to vapor at high temperatures instead of catching fire. However, it might catch fire if the brake fluid is spilled over a hot engine component, such as the exhaust manifold.
Marc is a Young mechanic working full-time in a big garage in Texas. He’s graduated and is well educated in the automobile industry and aims to open his own shop someday for his clients.