The Landlubber's Guide to the Marine Diesel Engine

Is the diesel engine fitted to your new boat the same as the version fitted to your car or truck? The answer is a qualified yes, but there are certain differences, especially when it comes to cooling and general maintenance. What do you need to know if you are to maintain your marine engine properly over the months and years ahead?

Watchful Eye

Like its landlubbing counterpart, the marine diesel engine requires oil and water to work properly. You also need to keep an eye on certain moving and consumable parts, such as the belt that transfers power from the engine to operate the alternator and water pump.

Make sure that the belt is always tight according to manufacturer specifications. You can generally tell if something is wrong if there are any black deposits in or around the pulleys. This indicates that the belt may be slipping and some rubber is being ground away. However, make sure that you do not overtighten them to compensate, as this will cause issues with the bearings that support the pulley wheels.

Engine Maintenance

When it comes to oil, just make sure that the levels are correct and that you change the lubricant as recommended by the manufacturer. You will need to keep a weather eye on the internal seals and gaskets, as once again, these are consumables and will wear out given time. It may certainly take months or years for this to happen but watch for any signs of an oil leak around the engine tray or traces of oil within the water cooling system.

Cooling Systems

As you know, your diesel truck is cooled when it drives down the road, and air flows over the water within the radiator fins. However, in the case of a marine diesel engine, the fresh water within the motor is actually cooled by the seawater instead. Here, you will need to check the intake area and filter fairly regularly to make sure that the seawater can flow into the system without restriction. Sometimes, foreign objects or even clumps of seaweed can accumulate around the filter or the outdrive. If this happens, the vessel may overheat quite quickly.

Regular Overhaul

Just like your truck, regular service is important. If you take the vessel to a marine diesel service provider, then they will do what is necessary to keep you on the open water as long as possible.