I recently rebuilt my engine and after many carb problems finnally got it running great. Problem is, the temp guage stays on cold for a long time then shoots to about 3/4 hot then creeps up to hot. I did accidentally run the motor without the water on it about 30-40 seconds (bonehead), but I pulled the impeller apart and it looked okay. Now I know that's pretty subjective, but it was brand new before and still looks that way. I swapped my electric guage with a mecanical one and it is indeed getting hot (about 210). the manifolds, thermostat, and impeller are new. The risers are not new.