Del mar

Morning,

Some discussion here at work.

When bleeding brakes should the car be running or not ?

When not on, the pedal becomes rock hard, only for it to go a little soft when the Servo starts working.

Thanks

Del

simo

off

AndyB_WRX

On, otherwise its not servo assisted

Paul666

I would say off, with the key just far enough to undo the steering lock. You should not need servo assistance to bleed brakes as you are not trying to push, however many, pistons onto pads to stop the car. If you have it running the ABS will kick in, and that will reduce pressure to what it will see as a locked wheel(s).

Normski

Engine off.

JohnD

iTrader: (5)

If that was the case then everytime the car stopped and you applied the brake, it would start rolling again?


You don't need the servo assistance to bleed, if you did there would possibly be a problem in the system somewhere.
JohnD

Paul666

John, have you never sat with your foot on the brakes and you feel the pedal start to drop ever so slowly as the ABS releases the pressure, and if you think about it, as soon as you get movement the ABS will apply pressure again.

Paul.

Yamarashi

Bleed the brakes with the engine OFF you are opening the bleed nipple so there's no real force required to push the fluid through.

With respect to the ABS discussion thats also going on, unless times have changed ABS requires the car wheels to be rotating (ie speed being recorded on the speedo) before it becomes active. If the car is stationary the ABS does not think that all four wheels have locked up as the speed sensor and all the wheel sensors tells it you are totally stationary.