Typical Cooling System Maintenance Schedules*

* Check owners manual for engine-specific information, including maximum engine-hours between service.

	OPEN-COOLED GAS (FRESH WATER)	CLOSE-COOLED GAS (SALT WATER)	CLOSE-COOLED DIESEL (SALT WATER)
Rubber Raw-Water Impeller	Every year; two at most	Every year; two at most	Every year; two at most
Bronze Raw-Water Impeller	n/a	n/a	At overhaul or if leaking
Raw-Water Pump Rebuild	At overhaul or if leaking	At overhaul or if leaking	At overhaul or if leaking
Circulating Pump	Every few years or if leaking	At overhaul or if leaking	At overhaul or if leaking
Heat Exchanger	n/a	Every three years	Every two years**
Thermostat	Every few years or if sticking	At overhaul	At overhaul
Oil Cooler	Check for obstructions or leaks at springtime launch	When heat exchanger is cleaned	When heat exchanger is cleaned
Transmission Oil Cooler	Check for obstructions or leaks at springtime launch	When heat exchanger is cleaned	When heat exchanger is cleaned
Antifreeze-Cooled Charge-Air Cooler	n/a	n/a	Every two years or 2,000 hours
Raw-Water-Cooled Charge-Air Cooler	n/a	n/a	Every two years or 2,000 hours
Engine Zincs	Check every Spring—more often for boats kept on shore power	Check every 30 days and replace when 50% eroded	Check every 30 days and replace when 50% eroded
Belts	Every year; two at most	Every year; two at most	Every year; two at most