HELP over heating problem 3.0

[Beau12]

I have an overheating problem on my 3.0/lx it's a 1995 maxum.
I have replaced or checked
impeller
riser
exhaust blockage
thermostat
manifold
and some other gaskets

i have taken it to my uncle a mercury boat mechanic he can not figure it out (the best in our area) and I have taken it to the local marina and they can not figure it out!

It runs about 175 at half throttle but 3/4 throttle it slowly rises to 200


Help needed so I can sell it and get a real boat (true inboard)

 

[hoowahfun]

How about the water pump on the front of the motor?

 

[Bt Doctur]

what about the complete water pump assembly ? therm should be a 140 so if that temp is confirmed by laser
you are hot.

 

[Bondo]

It runs about 175 at half throttle but 3/4 throttle it slowly rises to 200

Ayuh,..... Welcome Aboard,...... Have ya checked the accuracy of the gauge,..??

 

[alldodge]

Ayuh,..... Welcome Aboard,...... Have ya checked the accuracy of the gauge,..??

Yep there is also my question
Get an IR temp gun (under $20) and measure the thermostat housing temp and compare to gauge