On Tue, 25 Jan 2005 10:37:14 -0500, Ed > wrote:
>Vehicle is a 2001 Cherokke, 4.0

>Problem: I start the vehicle and bring it up to operating temperature (gauge
>reads between 190/210). Heat in vehicle works fine.

>On two occasions I was driving along when a warning chime sounded and the "Check
>Gauges" light came on (I had been driving for roughly a half hour...outside
>temperature was in the 20's). I looked at the temperature gauge and it had shot
>up all the way into the red zone (260). The first time it happened I pulled
>over, shut the engine off, and checked under the hood. I didn't notice or feel
>anything that would indicate the engine over heating... no excessive heat,
>steam, odor, or "pinging". I restarted the vehicle and the gauge dropped back to
>210.

>A couple of days later, it happened again; only this time the "check gauges"
>light turned off and the gauge dropped back to 210 before I had a chance to pull
>over (fortunately this time it happened I was about 100' from my driveway).
>Again, no observable symptoms of excessive overheating.

>Once I was able to check things more closely, I noticed that the upper and lower
>radiator hoses were warm to the touch, and there was no pressure and very little
>coolant in it. The radiator and cap were just barely warm.

>There's no sign of any fluid leaks or lost coolant. The level in the expansion
>tank hasn't gone up or down. The electric fan has kicked in a couple of times,
>but the gauge was still in the safe zone (about 230).

>I replaced the thermostat (195), and it's still running the same way... engine
>warms up, heat is fine, but radiator, upper and lower hoses are barely warm.

>What could be the problem here? Weak water pump? Clogged or blocked hoses and/or
>radiator?

Thermostat in backwards?

You really ought to get it fixed before you blow the engine.