possible water pump issue?

[mwagne30]

I just stepped up my prop from a 14-1/4 x 23 to a 25 and I noticed a significant water temp increase while trolling. When at idle foreward, the temp rises to 190 deg F or better. this is quickly changed with a little throttle. My best guess is that at a slow speed, the prop is pulling water past the intake too fast and not allowing it to take water untill there is a higher demand from the pump. Any ideas? any similar experiances?

Up date- put old prop on and at idle we go 170 deg F or better, bump idle up to 1500 rpm and or increase speen and temp will drop to 150?? new impeller?

 

[SS MAYFLOAT]

Re: possible water pump issue?

While stepping up your prop, your engine is going to work a bit harder turning the prop causing it to increase engine temp. Above a fast idle, the water pump is able to move the water faster through the cooling system to remove the heat. So in a since, at slow speeds, the water flow is slower and not removing the water fast enough to cool the engine.