3.0l omc sterndrive overheating

[bska]

Temp slowly climbs when trolling(220) take it for 5 min drive at full speed and cools right down to 150. Troll for 1/2hr and back up to 220. Any ideas? First things to check....TIA

 

[Bondo]

Temp slowly climbs when trolling(220) take it for 5 min drive at full speed and cools right down to 150. Troll for 1/2hr and back up to 220. Any ideas? First things to check....TIA

Ayuh,..... Welcome Aboard,.... Change the Impeller,.....