ImQuattro®

First I thought I had air in the system -possibly from having the bleeders open when pushing back the pistons having just installed new pads and rotors all around. During that, I cleaned and lubed all the slide pins and all pistons pressed back normally.
During the first drive to seat the pads the pedal would press right to the floor with only moderate action from the brakes. The brake light on the dash also came on. So I returned to my shop.
I figured I had air in the system so I bled the entire system (I had a helper work the pedal). Nothing major as far as bubbles. Topped the fluid off and went back out for a spin.
Only a bit better, still had lots of pedal fade and the brake light still came one when braking hard.
Am I looking at possibly a new master cylinder or what?????

~I have no leaks, stainless lines, new pads & rotors.

~System worked decently before R&R of pads/rotors but the brake light had been lingering ON a couple times after starting the car the past week or two.


Thanks in advance...
~Nate

gtivr6turbo

gotten the fluid to low and pushed air into the lines at the resevoir.

tpierce

the car is fine, it will drive okay, the light comes on because the accumulator (the bomb) is not able to keep the hydraulic pressure up under hard braking. Also, just to let you know, you don't need to open the bleed screws to push the pistons back in, and you really shouldn't beat too much on brand new brake pads until they are fully bedded in. They run hot anyways for the first 100 miles or so, so you beating on them can cause pad fade and boil the fluid. Either way, G60s will start fading with a couple of hard, high speed stops anyways.

tpierce

the brake light wouldn't come on from air in the lines, only if the resivoir was almost empty, the hydraulic fluid level was really low, or the hydraulic pressure dropped suddenly, as it did to him perfroming sudden stops.

TabulaRasa

After you compress the pistons down to install new pads, you need to press the brakes a couple of times before the pistons come back out enough. This is especially true if your rotors are worn.

ImQuattro®

go down the slippery slope of bomb and master cylinder.

I usually don't brake as hard as I was when seating the pads so the car feels normal when braking under normal conditions.... The brake light only comes on when really standing on it.

ImQuattro®

standing on it and sometimes for a couple seconds after startup -longer than other dash lights.

kday

I just replaced my pump. Initial symptom was flashing brake light under hard braking and on a couple of occasions the pedal went to the floor with weak brake effect. My bomb is fine.

But since you just did the brakes before the problem occurred, I'm guessing it's related to the brake job.

kinderutz

i just did my bomb and it's ok now.

Zwoobah

did you pump the brakes before you tried driving it?