Trev,

What your saying makes a good bit of sense to me. Your logic is supported by what physicists and engineers know about how air acts in a closed system. As for the previous comments of other posts, it made little sense to me that you have to worry about the front end up in the air to get the air out of the MC. In fact, the opposite thing is what needs to be done. And I might add, that many vehicle manufacturers recommend that very procedure for cooling system bleeding, as well as, brake bleeding. Nuff said, it is a fact of physics. Parenthetically, I never understood why the MC mfrs. didn't just put a bleed screw on the MC and be done with it.

So, what to do about all this? You know its kind of uncanny that all along I was trying to picture how my pressure bleeder was going to push air down all the way from the MC to the calipers. Air is very resistant to going downward when it is mixed with liquid. I wonder if that is why many prefer the vacuum method; however, I can't see much difference in trying pull air down either.

I wonder if I can take my previous MC and install a bleeder screw (or two ?) on it? Anyone ever do this successfully?

Anyway, I bench bled the MC and the lines (2qts of DOT 4), and I now know that the MC was not bad unless I got a bad new one. So either your theory is correct and/or there is another problem. I am now hearing for the first time a knocking sound coming from the rear of the vehicle when the brake pedal is held down.

Btw, do you know what is the best or sufficient psi for pressure bleeding? Mfr. of the bleeder I have says to use 10-15 psi. I was shocked at how Mechanique said he was pressurizing to 25 psi and that his MC reservoir was bulging out. However, perhaps a higher psi is better. Is more better?

diyer