<quote>
I very carefully loosen the pressure cap til it's loose enough to let steam escape. I hear the boiling sound under the intake manifold. I tighten the pressure cap and it instantly quits.<quote>
This is because of the properties of water (even mixed with coolant). basically when your coolant is under pressure, it has to get VERY VERY VERY hot in order to boil. as soon as you open the cap, the pressure is released and the coolant can boil throughout the system.
I very carefully loosen the pressure cap til it's loose enough to let steam escape. I hear the boiling sound under the intake manifold. I tighten the pressure cap and it instantly quits.<quote>
This is because of the properties of water (even mixed with coolant). basically when your coolant is under pressure, it has to get VERY VERY VERY hot in order to boil. as soon as you open the cap, the pressure is released and the coolant can boil throughout the system.