normde2001
Elite Member
- Joined
- Mar 10, 2002
- Messages
- 4,163
"The question is........is it normal for there to be back-and-forth between the radiator & sub-tank???????"
Yes, that is the sole purpose of the "sub-tank", (overflow bottle). Before the mid '60's when you filled the radiator of a water cooled engine, when reaching op temps water would blow out the overflow tube, leaving 1-2" of permanent air space in the radiator. Since then, an overflow bottle was added to every water cooled engine in the world to syphon that water back into the radiator when it cooled. Fill the rad, then fill the bottle to the line or a little over, the water should rise to near full when hot and lower back to the line when cool. Anything other than that is a problem.
Yes, that is the sole purpose of the "sub-tank", (overflow bottle). Before the mid '60's when you filled the radiator of a water cooled engine, when reaching op temps water would blow out the overflow tube, leaving 1-2" of permanent air space in the radiator. Since then, an overflow bottle was added to every water cooled engine in the world to syphon that water back into the radiator when it cooled. Fill the rad, then fill the bottle to the line or a little over, the water should rise to near full when hot and lower back to the line when cool. Anything other than that is a problem.