The ABS hydraulic controller doesn't need to be flushed on its own. We're supposed to flush brake fluid every few years because it absorbs moisture out of the air and we want to get rid of that. Water lowers the boiling point of the fluid from well over 400 degrees to 212 degrees. That can lead to one form of brake fade, and it promotes corrosion of metal parts. Unfortunately, since we don't have much trouble with brake fluid, very few people actually change it.
My concern with running the engine is two-fold. First, that is done to power the power brake booster, and that tells me you're pedal-bleeding the system. I almost never resort to that. Second, I suspect you pushed the brake pedal all the way to the floor. That must never be done unless the master cylinder is less than about a year old. Crud and corrosion build up in the lower halves of the two bores where the pistons don't normally travel. Running the pedal to the floor runs the pistons over that crud and can rip the lip seals. Most commonly you'll end up with a slowly-sinking brake pedal when you hold steady pressure on it, and that often doesn't show up for two or three days.
The only method I use to bleed brakes is "gravity-bleeding". Simply open the bleeder screws, loosen the cap on the reservoir to prevent vacuum from building and impeding fluid flow, then close each bleeder screw when fluid starts flowing with no air bubbles. Irritate the brake pedal with your hand to wash the few remaining bubbles into the calipers or wheel cylinders, then open each bleeder screw once more to let those bubbles out.
Friday, November 27th, 2020 AT 9:12 AM
(Merged)
