over heating in no wake zone

[Kevinator]

I have 1990 mercruiser 4.3 alpha one out drive it runs very strong, although the other day when cruising through the marina at idle speed the water temperature gauge was reading 240 degrees, so I applied a little more throttle and the temp came down some. When I started cruising at a more normal speed the temp came down to 120 degrees. Is this normal?

 

[Don S]

Re: over heating in no wake zone

When was the last time the raw water pump impeller was replaced?
That is the first thing to look at in any overheat problem. Lots of things can take them out.

 

[butchkrasniqi]

Re: over heating in no wake zone

just change the water pump, that means the water pump is all worn, when you are at higher rpm it turns faster, lower rpm it's not getting enough water