I have a problem with my wrangler overheating which seems odd to me. It is a 4.0l engine. Under normal steady driving, there is no problem. When stuck in traffic, on a slow trail ride, or just sitting at an idle, the temperature can jump from normal (210F) to hot (250F) in about 15 or 30 seconds. If I see it start to rise, and shut off the engine, wait a minute and restart, it might either drop quickly back to almost normal (210~220) or it could be pegged at top of the gauge (260+). I can always bring it back down to almost normal by bringing the RPMs up to at least 2000, either driving, or if I am stuck in traffic, by revving the engine a little. once the revolutions are up to over 2000RPM it only takes 15 or 30 seconds to bring the temperature back down.
About once a week, after starting, I sometimes hear a few "chirps" from the belt. My thought is that the water pump is dying, therefore it is resisting the belt sometimes and making it chirp. It also makes sense to me that the water pump might not be moving any water at low RPMs therefore the water near the temperature sensor can heat way up, but at higher RPMs it kicks in and moves all the cooler water from the radiator past the sensor and cools it down quickly.
I am no mechanic, so I don't know if my theory makes sense. I would appreciate any opinions.