If your brakes get too hot it could boil your brake fluid. But if your fluid boiled would you need to flush and bleed the brake system?

 

Assuming your boiling fluid didn't cause you to lose all braking power and slam your car into the barrier in turn 5, then yes, you will definitely want to bleed the brake system.

Did you boil your brake fluid, or just asking hypothetically?

 

They at least need to be bled, at the same time I would put a better fluid in there as well.

When the fluid boils, you create air pockets in the lines. Since air is compressible and brake fluid is not, you'll notice a soft, spongy pedal until the system is bled. If left uncorrected, this of course could lead to a dangerous situation.

 

its a good idea to bleed your brakes somewhat frequently if you "race" at all....as you are right...it can boil...it only takes a few ounces to change out the fluid in the caliper....a miti-vac vacuum bleeder makes this super easy.

Dot 3 is the lowest boiling point fuild. dot 4 is better but not many stores have 4 sitting on the shelf. You can mix 3 and 4....but using anything else you need to clear out the whole brake system. I tried the dot5 and 5.1 fluids when i was racing motorcycles...the boiling point is really high but the "feel" is not as good so I don't recommend them.