BillGrissom
Well-Known Member
Mostly good answers. In our cars, there is a gap at the bottom between the MC and booster. Any brake fluid leaking past the MC piston seal should run down the gap. Normal glycol brake fluid eats the paint off the firewall underneath the booster (common). The only way it could get into the booster is if someone plugged the gap w/ RTV or such, installed things wrong, or the suggested "spraying mist".
No vacuum exists on the booster where the MC bolts up. If you peer inside, there is a rubber belows that holds the vacuum, like the inside surface of a donut. However, not a dumb question because many newer boosters have no such bellows and rely on the MC to seal vacuum (square O-ring seal where MC bolts). My 80's M-B are like that, with a thin pancake booster like my minivans. Thick boosters like the 95 Breeze I put on my 65 Dart do have that internal bellows, at least I recall testing one without an MC bolted up and it moved fine, just like an old Mopar one.
Not good when the booster sucks brake fluid. I found fluid in both my M-B boosters, so changed MC's. I am less concerned now that I have DOT 5 silicone fluid in those cars. It was a pain getting the glycol out of those booster using rags.
No vacuum exists on the booster where the MC bolts up. If you peer inside, there is a rubber belows that holds the vacuum, like the inside surface of a donut. However, not a dumb question because many newer boosters have no such bellows and rely on the MC to seal vacuum (square O-ring seal where MC bolts). My 80's M-B are like that, with a thin pancake booster like my minivans. Thick boosters like the 95 Breeze I put on my 65 Dart do have that internal bellows, at least I recall testing one without an MC bolted up and it moved fine, just like an old Mopar one.
Not good when the booster sucks brake fluid. I found fluid in both my M-B boosters, so changed MC's. I am less concerned now that I have DOT 5 silicone fluid in those cars. It was a pain getting the glycol out of those booster using rags.
