20 Probable Reasons of Reduced Ship Auxiliary Engine Power

What are the 20 Reasons of Reduced Ship Auxiliary Engine Power

The performance of a ship’s auxiliary engine is essential for a continuous power supply on board. A sudden blackout situation due to any malfunction in the auxiliary engine can cause significant disruption in operations and have devastating consequences for the safety of the ship and its crew. Hence, it is essential to identify any reduction in the performance of the auxiliary engine due to wear and tear or other factors as early as possible.
A wise marine engineer always runs the minimum number of generators and looks for the maximum load. Not only does this give the auxiliary engine goodwill, but it also reduces overall fuel consumption and harmful emissions.

Lower engine performance results in higher exhaust temperatures, lower peak pressures, and lower performance. When the power of one generator degrades, another generator must be run in parallel to supplement the power demand.

Marine engineers need to be aware of possible causes that can lead to power loss from auxiliary engines.
In this article, we explore the various factors that can lead to a reduction in the performance of a ship’s auxiliary engine and how such situations can be avoided. Every ship are equipped with an auxiliary engine that operates on diesel or heavy fuel oil and helps to power the ship when there is no onboard power generation available.

Below are 20 possible causes of reduced power and performance of auxiliary engines installed on ships.

Ship Auxiliary Engine Power

Too low Fuel Oil pressure

Fuel oil pressure less than the required specification can cause serious engine problems. Too low fuel oil pressure could be due to a bad fuel oil pump or fuel oil viscosity. If you find that your fuel oil pressure is low, it is essential to take steps to fix the problem before it causes further damage.

Grade of Fuel used

As for the type of fuel burned, fuel oil pressure plays a significant role in determining the type of fuel used. Fuel oil pressure reduces by changing the grade from HFO (Heavy Fuel Oil) to MDO (Marine Diesel Oil), MGO (Marine Gas Oil), or LSFO (Low Sulphur Fuel Oil).This drop in fuel oil pressure means reduced engine power and efficiency. Additionally, it is essential to note that burning different fuel types can affect emissions and air quality. Therefore, it is necessary to choose the right fuel for your engine and avoid polluting the environment.

Fuel leak from the fuel injection system

Common rail fuel injection system min

The fuel injection system is an essential engine component responsible for supplying fuel. If the fuel pump parts are worn out, such as the plunger and barrels, it will cause a fuel leak, resulting in a drop in fuel pressure at the delivery point. This fuel leakage can lead to other problems, such as poor engine performance, increased emissions, and poor fuel economy. Therefore, it is essential to check your fuel system regularly to ensure that all components are working correctly and that there are no signs of wear or leaks.

Fuel Temperature

Fuel temperature is an essential factor in the performance of any engine. Excessive fuel temperature can reduce fuel viscosity and adversely affect fuel pressure. High fuel oil temperature can cause the engine to run inefficiently, losing power and efficiency. It is important to keep the fuel temperature within acceptable limits, to ensure optimum engine performance. Fuel temperature depends on the type of fuel used in the engine.

Peak Pressure Difference

Pmax Indicator

The peak pressure differentials between individual cylinders are one of the essential factors in determining overall engine performance. Differences in ignition pressure between cylinders can lead to reduced power, torque, and fuel consumption. It can also cause misfires and increased emissions. Maintaining uniform ignition pressure across all cylinders is critical to ensuring optimal performance. Balancing of Peak pressure in the cylinder is achieved by using quality parts, performing regular maintenance checks, and dynamic engine tuning after the maintenance.

Chocked Fuel Filter

The fuel filter plays a vital role in the performance of your fuel oil system. A blocked or dirty fuel filter can cause a decrease in oil pressure, resulting in reduced performance and even engine failure. It is, therefore, essential to regularly check the fuel filter and replace it when necessary. The fuel filter is installed in the fuel system before the engine and, at times, can be easily accessed through an access panel. A fuel filter is a screen or strainer that filters the fuel as it enters the engine, preventing particles from clogging up the injection system.

Improper valve clearance

Improper valve clearance can have severe consequences for the engine. It can lead to decreased performance and excessive wear on internal components. The clearance between the intake/ exhaust valve and its guides is essential. If the clearance is more than required, it can increase friction between the parts resulting in increased fuel consumption, higher emissions, and inefficient power output. Further damage may include burnt or stuck valves due to carbon build-up caused by improper combustion or improper valve clearance. Therefore, regular maintenance should be carried out to ensure no excessive gap between the valves and their guides which could cause severe damage to the engine.

Damaged Exhaust Valve

A damaged exhaust valve or seat can be a severe issue for any engine. If the valve or seat is not sealing properly, it can cause a blow-by of exhaust gasses on combustion and increase the amount of unburned fuel released into the environment. A damaged exhaust valve or seat will increase emissions and decrease fuel efficiency. In addition, it can also cause engine misfires and other performance issues. Identifying and repairing a damaged exhaust valve or seat as soon as possible is essential to prevent further damage to the engine and ensure optimal performance.

High Exhaust Back Pressure

High exhaust back pressure is a common problem faced by many Engines, caused by a flaw in the exhaust piping installation or the silencer becoming fouled. High exhaust back pressure can lead to increased engine stress, lower fuel efficiency, and increased emissions. It is identifying the root cause of the problem before implementing necessary repairs. To tackle this issue, It is also essential to regularly check for signs of high backpressures, such as noisy engine performance or black smoke from the exhaust system. Despite the promise of reduced engine stress, high backpressure can lead to poor fuel efficiency and increasedemissions.

Fouled exhaust Passages

An engine’s fouled exhaust passages can significantly cause decreased performance and increased fuel consumption. If a contaminated exhaust manifold is present, it can lead to a hindrance in the exhaust gas flow and an increase in the temperature of the exhaust. This issue needs to be addressed quickly, as it can severely affect engine performance and fuel efficiency. Knowing how to identify and combat this problem is essential for Marine Engineers

Inadequate supply of fresh air

Adequate supply of fresh air is essential for efficient combustion in any process. Without the right amount of fresh air, there will be a reduction in the scavenged air supply, which can lead to an imbalance in the combustion process. Inadequate air supply means that not only will the fuel and energy efficiency be reduced but also, it can lead to potential health hazards. Therefore, it is essential to ensure a sufficient supply of fresh air.

High intake air temperature to T/C


When a ship sails in particularly hot regions, the atmospheric air sucked in by the turbocharger will be much higher than usual. This results in high intake air temperature to the Turbocharger (T/C). To maintain efficiency, the T/C must operate at lower temperatures.

One way of doing this is by periodically cleaning the intake air cooler between the turbocharger and its intake manifold. A clean Intercooler and intake manifold can help reduce the incoming air’s temperature and prevent it from entering the T/C at too high temperatures for it to handle. Additionally, proper maintenance must be carried out regularly to ensure that all components are working correctly and that no overheating occurs due to poor maintenance or weather conditions.

Too Low Charge Air Pressure

The charge air pressure of an engine is a critical factor in ensuring the machine’s optimal performance. If the scavenge air pressure is too low, it can cause many issues with combustion and cause a decrease in performance. The insufficient amount of air required for combustion would not reach each cylinder and result in poor fuel efficiency, clogged filters, and misfiring. Low scavenge air pressure can also lead to increased wear and tear on the engine components due to improper combustion processes.

It is essential to ensure that the charge air pressure is kept at a suitable level for optimal performance to prevent these issues from occurring. Appropriate charging pressure can be done by regularly checking the scavenge air pressure levels and making necessary adjustments.

High Charge Air temperature

With the development of automotive technology, it has become increasingly important to understand how high-charge air temperature affects engine performance. The cooler thermostat is the main factor in deciding the temperature of the output air supplied to the engine. If this setting is too high, the air temperature will increase significantly, leading to decreased engine performance and fuel consumption. Appropriate measures must be taken to reduce or manage high-charge air temperatures To ensure optimal performance and fuel efficiency.

Dirty Intercooler

A dirty intercooler is a severe problem that can negatively impact an engine’s performance. When seawater is used to cool the air, it needs to pass through an intercooler that should be kept clean and free of contaminants. If the intercooler is contaminated or dirty, then it will not be able to allow enough seawater to properly cool the air before it enters the engine, leading to an increase in exhaust temperatures and reduced fuel efficiency.

Supply of intercoolers with high seawater temperature

The increasing seawater temperature is a significant challenge for the supply of intercoolers. If the seawater temperature is on the higher side, the air cooled in the air cooler will be warmer than usual, which will adversely affect its performance. High charge temperature due to hot seawater can lead to a decrease in the efficiency and reliability of the system.

Sea Water bypass from air cooler is open

The air coolers provided with an S.W. bypass valve are designed to control the cooling medium, i.e., seawater. If the bypass is open more than required, it can lead to inefficient cooling of the system and even damage the machine components due to excessive heat. Therefore, operators must ensure that the S.W. bypass from the air cooler is appropriately closed and not left open for too long.

Worn/damaged Compressor wheel, turbine, or nozzle ring      

Worn or damaged compressor wheels, turbines, and nozzle rings are a significant issue for turbochargers. If these parts become fouled or damaged, it can obstruct the passage of exhaust gas or decrease the amount of fresh air being fed into the turbine. Fresh air starvation can drastically reduce performance and efficiency. Additionally, there is an increased risk of turbocharger failure due to excessive heat and pressure build-up. To prevent this from occurring, it is essential to regularly inspect these parts and replace any that have become worn or damaged.

Leakage in Scavenge Air

Leakage of scavenging air from the inlet pipe to the cylinder can be a significant problem for an engine. Incomplete combustion will occur due to less air supply, which can reduce the engine power output, increase fuel consumption and cause other dangerous problems. Leakage of scavenge air should be detected and repaired at the earliest opportunity to maintain the optimum performance of an engine and prevent potential damage

Improper tappet clearance adjustment

Setting the tappet clearance is an essential step in adjusting an engine. If the tappet clearance is set improperly, it can lead to various issues with your engine’s performance. Improper tappet clearance adjustment can cause problems from inefficient fuel consumption to an engine misfire.

Incorrectly adjusted tappet clearances will allow either inlet or exhaust valves to open more or less than required, resulting in too little or too much air entering and exiting the cylinders. Wrong tappet clearance can lead to poor combustion, low power output, increased fuel consumption and increased emissions and noise levels.

You must adjust the tappet clearance accurately to ensure your engine runs at its optimal performance level. Failure to do so will result in costly repairs down the line; therefore, you must take extra care when adjusting this part of your engine.

The Third Engineer

A marine vessel engine designed primarily to provide power for purposes other than propulsion

Anything that prevents fuel from entering the cylinder leads to a loss of power when the engine needs more fuel than is injected

Excessive pressure and temperature in the exhaust manifold and anything that prevents fuel from entering the cylinder will lead to a loss of power. Compressor discharge air temperature and compressor pressure ratio. turbocharger speed. Coolant heat removal and engine outlet coolant temperature.

Blog Conclusion

We hope you enjoyed reading our article about Reasons for Reduced Ship Auxiliary Engine Power. We know that many factors can significantly impact an engine’s power, but we hope these tips will help you maintain your engine power. Don’t hesitate to contact us anytime with questions or comments by sending us a message on social media at https://www.marinediesel.co.in/. We would love to hear from you. Thank you for reading; we hope you learned much from this article.

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