Essential Life-extending Maintenance for Your Diesel Marine Engine

All marine diesel engines require upkeep and maintenance in order to ensure they remain functioning. Regardless of the size of the engine, even the smallest type of problem if left untreated, can potentially transform into a larger, more serious issues. Which will ultimately cause your boat to break down.

Follow The Maintenance Guide

Marine engines come with their own maintenance schedules which should always be followed rigorously to ensure there are no problems. Maintenance tasks may at times seem an additional unnecessary and time-consuming expense, however keeping up with maintenance is always cheaper than replacing the whole engine. The majority of engines come with an hour metre - this makes it easy to keep track of maintenance tasks. If your engine does not come with an hour metre, it is advisable to install one.

General maintenance tips include the following:

• Ensure the engine is kept clean
• Check the maintenance plan regularly to look for any upcoming part inspections and replacements
• Make sure that all moving parts are well lubricated

Before using the engine check the following:

• That the raw water flow is unobstructed
• All bolts and fastenings are firmly secured
• Any unusual sounds when starting up the engine as this will alert to potential problems

After using the engine and waiting for it to cool:

• Flush out all traces of salt water with fresh water
• If the boat will be stored for long periods of time, drain the fuel tank and disconnect the battery

Top Maintenance Tips

The Cooling System

The cooling system plays a critical role as it prevents the engine from overheating – heat can build up quickly and reach high levels in a diesel engine - issues with the cooling system mean that the engine can overheat very quickly causing serious damage. Whatever type of cooling system the boat has, maintenance is essential.

Many smaller vessels use a cooling system which involves a freshwater loop and a heat exchanger to prevent the engine from overheating. One common reason why this type of system may fail is due to blockages in the flow of raw water. The raw water strainer or sea strainer should be regularly checked, as debris, marine plants and barnacles can cause obstruction. It is also important to check the impeller, as this raw water pump is one of the parts most likely to fail as it can be easily damaged by any raw debris. It is also prone to cracks at the base of its blades, this is an indication that it needs replacing. Failure is even more likely if the impeller is unused for long periods of time – making it important to carry a spare impeller on board. It is also advisable to check the wet exhaust each time the engine is started.

Ensure The Fuel Is Clean

This is one of the most important aspects of maintenance and involves ensuring that the fuel tank itself is regularly cleaned and checked for any signs of corrosion or rust. Both the primary and secondary fuel filters should be regularly changed in accordance with the manufacturer’s guidelines. The primary filter is the largest and removes any large particles from the fuel, the function of the second filter is to catch any fine particles of dirt or water that may have escaped from the primary filter. The filters also help to prevent water caused by condensation, as well any dirt or debris from reaching the fuel injectors – these highly sensitive parts are essential for the combustion process and are easily damaged. Some condensation in the engine is inevitable, however any water has the potential to spawn micro-organisms which can quickly clog the system. This can occur when fuel is left sitting in the tank for extended periods of time whilst the boat is not in use. Old fuel should be changed, and the fuel tank cleaned out to avoid any potential problems.

Use The Correct Type Of Oil

Oil and filters are not an area to economise on. Always follow the manufacturer’s guidelines with regards to using the recommended type of oil. Good quality oil with a high viscosity is much thicker and therefore more protective. This protection is essential to the diesel engine which works under high pressure and reaches extremely high temperatures. The oil level should be checked before use, inspected at regular intervals and replaced as often as stated by the manufacturer’s guidelines – this is typically at 100-hour intervals, although smaller engines may need even more frequent changing. A change in colour to the oil may indicate that there is excessive water, and the problem needs fixing.

Our Services

We supply a wide range of diesel engines by leading manufacturers such as Yanmar. For more information on our marine diesel engines, parts and other services, get in touch with AT Wilde.