coolant boiling in overflow reservoir after sessions

[luis]

is it normal for the coolant to boil in the overflow reservoir after a track session? i participated in the velocity adventures event this weekend at H2R (which was repaved since the last event in february). and noticed my coolant boiling, however, my water temp guage in the cluster didn't change. i'm currently on the stock radiator, but i do have an aftermarket rad (53mm koyo) that i plan on installing sometime.

[goofygrin]

radiator cap... replace it.

[POS Racing]

radiator cap... replace it.

+1

[luis]

thanks!