My truck has been sitting for some time now, and I need to bleed the brakes. The master has been empty or nearly empty. I have never had to bleed a master cylinder before. How do I go about doing it? I am gonna make one of those pressure bleeders like KidJethro made for bleeding the brakes, but obviously I need to bleed the master first. Can I do it on the vehicle, or do I have to take it off? That should be it right? the four corners and master cylinder....would the proportioning valve have air in it? How do you bleed that if it does? Thanks.