I've never had this problem, but this is what I would suggest:
Check your electric fans and make sure they come on when they're supposed to.
When you drive there's a lot of air rushing under your hood, thus cooling down your engine; but when you stop at a traffic light, there's no much air which increases your engine temperature. That's usually when your fans come on (specially during summer). When your engine reached a certain temperature, it triggers the fans which cool your engine down.
Here is what I would do:
Turn on your car and let it warm up until it reaches normal operating temperature. When the gauge gets to the middle, wait and check if the fans come on. They should come on soon after your gauge crosses the middle. If they don't turn on at all, or late, you need to fix that quickly, as you could (will) end up with bad engine damage from overheating (like blown headgasket, etc).
Also, check your level of coolant and make sure it is flowing thru the cooling system.
Tuesday, July 22nd, 2008 AT 4:58 PM