I just noticed that my coolant expansion tank cap
doesn't seal the expansion tank. There are the two
overflow holes just at the level of the lip of the
inner surface against which I assume the rubber
gasket is suppose to seat. On both my tank caps
that gasket doesn't sit tight against the lip; instead
it is 2-3mm above the lip.

Are there different expansion tank caps and different
expansion tanks? Would this cause the car to run
super cold? Cold to the point where the gauge barely
moves?

thanks,
chris