Bleeding Brakes...Engine on or off?

[Locknut]

I thought I read a post a while back that said your car should be running when you bleed the brakes...any ideas as to why? Vacuum assist? Easier to get the air out? Abs pump?

[BlueC]

I've never needed the engine running to bleed the brakes on any of my cars. A vacuum pump works very well to bleed the brakes, but you need an air compressor for that.

[Bwana]

I've never heard of bleading brakes with the engine running, somehow it doesn't sound like a good idea to me, but I could be wrong...? I've always done it with the engine off.

[elwesso]

you wont need the vacuum assist when the brakes are not really under pressure...