My '07 Grand Cherokee is indicating via temperature gauge that it is overheating, pegged on H. Multifunction indicator said "check gauges," for a second or so. In addition, "transmission over temp" fired on, only briefly. I checked the expansion tank, and it was bone dry this morning. Filled it close to 7/8'ths full with a 50/50 mix of coolant, and it still overheats. For the record, this is all occurring at idle. Upper and lower radiator hoses are hot, I get heat, no visible leaks, oil doesn't look like a milkshake. Engine is the 3.7 litre as well and it has slightly over 92K on the clock.

Cheers!

 

You say the radiator hoses are hot, but can you feel the coolant flowing through them? If not, you could have a faulty thermostat and the existing coolant is boiling over.

 

Is the cooling fan running? Obviously it should be!