My Impala has 80,000 miles on it. It has not ever come close to over heating, but at times the heat meter in the dash board just seems to die and go down like the car is off, While the fuel and speedometer continue working fine. It typically runs at halfway to the max in the summer and a little over a quarter of the way in the winter. I don't think there is an actual problem with the cooling system I think it just may be the electric wiring in my car, although their could be some gunky coolant because it is dex cool. I know the Water pump could also be the issue but it has never overheated. I know for sure that it is not a head gasket because my oil looks prestine and my car doesn't smoke. I am wondering if I should be concerned. Also if the gasket on the water pump is leaking would it take a long time to leak out the coolant. This started happening about 3 weeks ago and I drive the car 50 miiles to work and back everyday so I figured by now the coolant would be low but it isn't yet.