temperature gauge bouncing up and down
 

Hi~

I have been working on my 1973 450 SEL for some time now. Anyway, I am driving along and the temperature gauge will move up and down and then slide up to the up position. Sometimes it does it the other way. Why does it do this? New temperature sensor required? Can this indicate cooling system problems?

Thanks

Check the coolant level. If the temp sending unit isn't bathed in coolant, it'll shoot up when steam hits it. Same thing with a blown head gasket... if combustion gases hit the sending unit it'll behave erratically. Do you notice any overpressure conditions in the cooling system or bubbling in the radiator?