OMC hot at high RPM

bigtony3ca

Member
Joined
May 28, 2005
RO Number
17558
Messages
6
I have a '90 Four Winns Liberator 221 w/ a 454 OMC. The engine is running hot at anything over 3000 rpm. At under 3000 rpm it runs great, temperature sits at 150-160 degrees.

The boat has only ever had freshwater use and only has 200 hours on it.

I have changed the impeller and the thermostat....same problem. Over 3500 rpm the temperature begins to creep up unitl I back off the throttle.

I have used an infrared thermometer and the sending unit is indicating the correct hot temperature. As well, both risers are heating up equally.

Any thoughts???

Thanks
 
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