Quote:
Originally Posted by m6-lt1
after a drive I notice the lower tank is filled PASSED the line (about 2/3) ... During my last track day I noticed the lower tank was filled up to 3/4 ... After the next session it had dropped back down to 2/3.
If the car hasn't run for a while the coolant in the lower reservoir is exactly at the line just like when I originally filled it even though it was at 2/3 when I shut off.
|
What you describe is exactly how surge/expansion tanks work.
Our cars have a COUNTERINTUITIVE setup. The top tank is part of the pressurized loop. The bottom tank is the expansion tank.
So under normal operation, the bottom tank accepts excess volume of coolant from the loop when the loop is hot -- because water expands more than aluminum when it gets hot. So it needs somewhere to go, and that place is the lower tank.
And then when the engine cools back down, the coolant cools back down and then shrinks in volume and the pressure loop sucks that same "excess" coolant back out of the lower tank via the straw -- because the coolant shrinks in volume when it gets cold again.
The benefit of all this is a natural self-bleed action, so any small amounts of air that get into the pressure loop will work it's way out of the system via natural thermal expansion during and after a drive.
All of this is normal. Your car is normal.
