4.    Monitor Engine Temperatures: Overheating is one of the leading causes of engine damage. Always keep an eye on your engine’s temperature gauges, and if you notice any unusual spikes, shut down the engine immediately to avoid severe damage. 

Boat TEST recommends that when buying an inboard-power boat, you buy one with a closed loop cooling system and heat exchanger, particularly if the boat is used in saltwater. 

Regularly inspect the cooling system, including water pumps, impellers, and thermostats, for any signs of wear or failure.

5.    Ensure Proper Ventilation: Car engines are less exposed to moisture and salt, which means they are less prone to corrosion-related damage. Marine engines, especially those used in saltwater environments, are constantly exposed to saltwater and high humidity. 

Corrosion is a significant issue that affects the longevity of marine engines, even with good maintenance.

A well-ventilated engine compartment ensures the engine receives clean, cool air, which helps to prevent overheating and improves combustion efficiency. Poor ventilation can lead to higher operating temperatures and reduced engine life.

BoatTEST recommends that with the engine running at 4000 to 4500 RPM you crack the hatch to the engine compartment and feel if air is being sucked in. If it is, your engine compartment does not have enough ventilation. 

6.    Run the Engine Regularly: Engines benefit from regular use. Long periods of inactivity can lead to internal corrosion, especially in damp environments. If your boat sits idle for extended periods, ensure you start the engine occasionally to circulate oil and prevent moisture buildup.

7.    Avoid Overloading and Over-Revving: Automotive engines generally run at a wide range of RPMs, with frequent breaks (such as when the vehicle is idling at stoplights). Because they have from 3 to 5 gears, or are automatic, an automobile engine generally runs between 1500 and 3000 RPM.

Not so for boat engines, which generally have to run 3500 to 4000 RPM just to get on plane. It is not unusual for boat engines to run at 5000 RPM for prolonged periods of time, which can shorten the engine’s life span.

BoatTEST recommends that boat owners simply operate their boats at lower speeds.  Not only does it save fuel, it’s more comfortable for guests, and is safer. It also can prolong engine life. 

8.    Winterize the Engine Properly: During the off-season, it’s vital to winterize your engine. This process typically involves draining water from the engine, adding antifreeze to closed systems, stabilizing the fuel, and storing the boat in a dry, protected environment. Proper winterization prevents freezing damage and corrosion while the engine is idle.

9.    Monitor Oil Quality: Always check the quality and level of oil before every trip. Oil that appears milky probably contains water or contains foreign particles that could indicate contamination, both of which require immediate attention to prevent severe damage. Don’t run the engine. 

 

10.    Check the Fuel Line Filters: Most inboard and sterndrive engines have a large remote fuel filter that keeps water and debris out of the engine’s injector system. Check the filter regularly and clean or replace the element anytime water or dirt is evident. Some engines also have an added inline filter on the engine itself—this cartridge should be replaced annually.

By following these expert tips and keeping up with regular maintenance, you can significantly extend the lifespan of your inboard gasoline engine, ensuring many more years of reliable performance on the water.