I have noticed that my coolant is always low (1/2 tank) when I check it periodically. No coolant in the oil or on my floor. What's up? Also, I notice that when I look into the radiator through the fill cap that there is a tube that runs up inside the radiator and ends about an inch before the top. What is this tube? Could my fluid be rising when its hot and spilling into this tube? If so, where the hell is it going? I have an overflow tank but never see any fluid in it.
There should be a tube from the radiator to the coolent recovery tank. When there is too much heat and pressure, it is supposed to go into the tank. When the radiator cools down, the suction is supposed to pull the fluid back into the radiator. Some cars didn't have recovery tanks, and the fluid just drained onto the ground. When you say half full, do you mean the recover tank, or the radiator. That would be a lot of fluid loss if it's the radiator. The recovery tank, though, isn't supposed to be full. There should be a "full cold" line. That gives room for fluid to enter the tank without over flowing.
May need a new radiator cap. Current one may not be holding the pressure and letting it escape out around cap. Does it drop to half and stay?
