What are the symptoms of boiling brake fluid?

[terrible one]

I was a bit unsatisfied with my stopping performance so I decided to bed in the brake pads proper (discs up front BTW). I went to a lone county road and did 5 or 6 runs braking from 80-30 mph full on stopping power. During the last, the pedal went a bit soft and closer to the floor. I went home and the front wheels were hot to the touch and I could feel the heat coming from the calipers/ rotors. After it cooled down I noticed an amazing improvement in stopping power, so at least I got the pads bedded in. The pedal feel was mostly back as far as I can tell. Anyways I think I may have boiled the fluid but I've never experienced this Thoughts?

[FLG]

Its a possibility, gas is compressible so you will have extended pedal travel.

I wouldnt worry though, what you did to get it there you will never actually experience in real world braking.

[tan top]

what FLG said    you wont get this with normal street driving ,


extended  pedal travel  .... going to the floor & car still not stopping , but not same as air in system ,    experianced that a few times when i was younger  ( pedel goes to the floor normaly after smelling burning disc pad smell   ),     on repeated high speed  braking for corners  or stops !   on non vented disc braked cars ,  few miles of no braking or light braking !! they come back   good idea to check the  pads though !!  cheaper aftermarket pads have had cracks in them when checked !!

[elacruze]

If the pedal went soft, you gassed the fluid. Brake pad fade alone won't affect pedal travel, only the pressure necessary to stop.
You need to drain out that old fluid and replace it, particularly the fluid in the calipers which will require removing them and bleeding them with the bleeder at the bottom. Otherwise old damaged fluid will remain in the bottom of the caliper bore.

[resq302]

Just curious why you have to remove the calipers?  Wouldn't the new fluid push the old stuff out?  Or at least power bleed them till it came out clean again?

[440]

what FLG said    you wont get this with normal street driving ,


extended  pedal travel  .... going to the floor & car still not stopping , but not same as air in system ,    experianced that a few times when i was younger  ( pedel goes to the floor normaly after smelling burning disc pad smell   ),     on repeated high speed  braking for corners  or stops !   on non vented disc braked cars ,  few miles of no braking or light braking !! they come back   good idea to check the  pads though !!  cheaper aftermarket pads have had cracks in them when checked !!

Same when I was young. I have never boiled the fluid though but have seriously overheated the pads to the point where you could stand on the pedal with both feet and the car still would not stop, even at 5mph. Quite scary when your headed downhill. I think a slot in the pad would have helped expel the gasses and many pads now have a slot/grooves for this. It's amazing how quickly street pads heat up, depending on pads 6 -7 good corners is all it takes to be able to smell the pads.

[elacruze]

Just curious why you have to remove the calipers?  Wouldn't the new fluid push the old stuff out?  Or at least power bleed them till it came out clean again?

The fluid won't push out the old stuff on the bottom of the bore, it will just swirl it around. Turning them upside down will allow any contamination or crystalized junk to run out. If it was my own, I'd take the calipers off so I could remove the hoses and drain them completely before bleeding.

[terrible one]

Thanks everyone for the info. Only two bolts to get the caliper off of there and drain the fluid out so I'll do that just in case.

tan top, I hear ya on the burning pad smell! I'll remember that smell forever now, I definitely got a good whiff of it