I had my boyfriend change my front brake pads yesterday on my 97 venture (they weren't too bad but needed changing) and he decided to bleed the brakes. All was dandy until we started the van back up and lost all brake pressure. We tried several times to bleed the brakes and each time seemed fine til the van was started back up. We even bled them with the van running. I had pressure again until the van was shut off and back on again. Again the brake peddle floored. I wouldn't think the master cylinder would go bad during a simple brake pad change. What could we be doing wrong if anything?

 

Well, problem fixed. It was indeed the master cylinder. Good thing it went while I wasn't driving.

 

You have ABS prolly and of course brake booster. When you are equppied with these, you shouldn't push the pedal all the way down to the floor when you bleed them.