over heat?

[boby]

I have two outboards engine. As soon as I reach about 3000 RPM the engine alarm signal and the gage indicates that the temperature is moving up. As soon as I slow down the gage comes Wright back. I had my impellers change.The engine is tuned up whith knew spark plugs and is very responsive.

Can any one help me ?
thank you

[jb123]

check pressure releif valve under lower right cylinder and also the thermostats above each top cylinder. lastly you could remove the water jackets to check for any corrosion blocking flow.