hyperion

iTrader: (2)

All,

I've been studying the manuals for the FD and I don't understand how the overflow bottle works. In the manual, the way of filling a drained coolant system is to pour fluid into the filler neck (connected to the overflow bottle) until you've put a little over 9 quarts into the system.

My question is: how the hell does this work? The overflow bottle is connected to the AST through the radiator cap. This cap is closed unless the pressure of the system exceeeds 0.9 bar. Plus, the cap is physically higher than the top of the overflow tank. I just don't understand how filling the overflow tank is supposed to fill the coolant system up.

This system is unchanged if you eliminate the AST. Now, your overflow bottle is connected directly to the radiator cap bypass tube. How does fluid from the overflow tank get all the way up to the bypass tube, and then past the cap (closed) into the engine?

Also, if the overlfow tank is at or near empty, can this cause problems? If so, how? When is there ever a vacuum on this tube? It would seem that it's either closed or under positive pressure when the cap is forced open.

Please shed some light on this one,

-ch