1986 5.7 260HP Overheating

[stlouisloui]

Hi Ya'll. New to me is a 27' Sport-Craft with a 1986 5.7L 260HP sterndrive.(940 Hours) This motor starts and runs great! It's fine until a little over 3000 RPM, when the motor temp rises quickly. As long as I run the engine at 3000 RPM or less I'm good. On a recent test run, when running about 3000 RPM the motor started loosing power. I noticed a crack and spewing hot water from the exhaust manifold boot to starboard. Do you think my issues are related? Any suggestions would be great. Thanks.

 

[sandkicker]

I'd start with the raw water impeller... doubt that leak would cause overheat.

 

[stlouisloui]

I should have noted that the water pump impeller was new this spring. Thanks.