Temp gauge rises quickly

[fastback4]

After 10 min. of engine warmup while driving the temp gauge rises quickly to the half way mark then within seconds it lowers to it's normal position at about 180/190 degrees.
If i stop at the store and leave the engine running, within a few seconds the temp gauge rises to about the halfway mark again, untill i drive or raise the engine rpm's a little. What gives here?........Tom

[robertisaar]

almost sounds like air in the system.

[fastback4]

I agree but how many times must the air be purged? Purging is done after engine reaches operating temps correct?.....Tom

[86FieroSEv6]

Nyet . . . merely running/driving the car does not necessarily purge the system.

[robertisaar]

Nyet . . . merely running/driving the car does not necessarily purge the system.

certain engines it will, like the 2.4 as used in a grand am, but no 60V6 is that easy.