Four cycle, 3 cylinder, liquid cooled, naturally aspirated, overhead valve diesel with glow plugs for quick starting. Swirl combustion chambers improve fuel efficiency and reduce smoke. Cooling System Standard heat exchanger cooling with optional keel cooling. Copper-nickel, tubetype heat exchanger has removable rubber end caps for easy cleaning, and no need for zincs. The bronze and stainless steel seawater pump with rubber impeller is gear driven, eliminating a potential failure point.