overheating merc 170 hp I/O FWC

[hcir68]

I have a 1989 larson 215 with a 170hp mercruiser i/o and it tents to run hot after 3mins at full throttle. I ussually then run it slow till it cools down. it is a fwc engine, does anyone know what it could be? antifreeze is full.

 

[WillyBWright]

Re: overheating merc 170 hp I/O FWC

If the water pump in the drive is weak, it'll run hot. Also if there is debris in the heat exchanger. The water pump is a bit of a job, but checking the exchanger is easy. The ends come off with a 9/16 wrench and the gaskets are usually reusable as long as you line them up with the impressions.

 

[Haut Medoc]

Re: overheating merc 170 hp I/O FWC

Take your heat exchanger to the radiator shop & have the fresh water side rodded/boiled out......JK