Evinrude 150 VRO overheating

[whaler31]

Hello all,

I just purchased a 1965 17ft Whaler Montauk, with an Evinrude 150 VRO. I think that the motor is around a 1988-1990. I was able to get the motor running after replacing the battery. The motor runs pretty well and pees a steady stream through the telltale. The water that comes out is nice and cool at first, then gradually warms to luke warm. After about 10 minutes, the water starts to come out hot and then it stops and just vapor comes out the pee hole. The head starts to heat and I shut the motor off. Is this a cl***ic sign of "need a new impeller", or something more sinister?

[boats.net]

Run a compression test first then check water pump, thermostats and pressure valves.