Indmar S985009 OEM Replacement Marine 160 degree thermostat. Used on majority of Indmar engines except the LT1 engine, use part #S986034.
Older engines equipped with a 143 degree thermostat can use the 160 degree thermostat. A engine running at 160 degrees will benefit better performance because fuel will atomize easier helping the engine run more efficient.
Thermostats can fail and what you use to replace it with is important. The only thermostat that will function properly is original equipment.
OEM Indmar Part
160 Degree Fahrenheit Thermostat
Marine Brass & Copper Construction
Suggest Replacing Thermostat after a Engine Overheat
Make sure to use thread sealant on thermostat housing mounting bolts to help avoid vacuum and water leaks.