overheating merc

[jmphoto]

I have 1994 175hp black max I have changed the water pump changed the stats twice rebuild the popet valve , removed the lower end to make sure there was a seal between the water pump and the out going gas chamber , flushed with vinegar finaly pulled a head to see if the water jacket was blocked it is clean . What is left ,it runs great at 1000 rpm above 3000 rpm the temp goes up untill the alarm goes off . its a twin and I have switched the temp sensor . I would love to repower but need to keep it running for another season or two . help

 

[blackgrady]

is it possible that it is overheating from a lean misfire? that will raise engine temps dramatically, even if the water pump and cooling system is working properly. check to make sure the engine has the required amount of fuel supply. maybe a clogged filter, pickup or primer bulb going flat? fuel pump going bad?

steve

 

[weatherbymag]

over heat

I have a pair of 98 mercury 150's

on my motor I had water pressure quages,

it may be worth putting a test quage on the water line to see if the pressure is okay