When does it run hot? If it cools okay at speed but cooks in the bush then airflow issues, bigger fan good, electric best with cut off switch for water crossings. Mechanical fan rough in mud/deep water. If runs too hot all the time, change the t stat and when you drain cooling system, pull off lower hose and see how fast it drains. Give you an idea if the rads getting plugged up inside. Upgrading to thicker rad ( more cores) is a good idea. Less need for fan assistance as it can radiate the heat away better.