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Finding and Fixing Common Marine Diesel Engine Issues at Sea

Finding and Fixing Common Marine Diesel Engine Issues at Sea

Having your ship subjected to routine maintenance by a reputable and reliable company that specializes in ship repair in San Diego is the best way to ensure your diesel engine does not break down out in the sea. But sometimes unpredictable circumstances can lead to the engine breaking down when you need it the most. Fortunately, troubleshooting diesel engine issues is not that difficult and every ship owner needs to learn how to do it for this particular reason.

When a diesel engine stops it is likely because one of the many processes gets interrupted. If you can find what went wrong and set it back on track, you will be able to get the engine going again. If not, you may need to hire an expert to examine what went wrong.
In this article, we are going to list some of the most common causes of a diesel engine failure, how to identify them and most importantly how to fix them.


You will likely become aware of this issue as soon as the warning lights and sounds set off. However, other symptoms may involve a sudden outburst of white or gray smoke or weird mechanical noises inside the engine. The engine may or may not stop working completely as a result.

Even if it doesn’t, if you witness some of these symptoms make sure to turn the engine off immediately. The most likely cause for this issue is the low oil level. Fortunately, it is resolved simply by adding more oil. Check the oil level in the engine with the dipstick. If the levels are low a refill should get the engine running properly again.

Another common cause is a clog in the oil filter. The only way to solve it is to change the filter. When changing the filter be sure to change the remaining oil as well. You will probably not be able to do this out in the sea, so try to find a place to dock as soon as you can. If neither of these issues is what’s causing the engine to misbehave, consider having an expert look at the engine.


Around 40% of the energy you get from burning fuel goes to the propeller. The rest of it is excess heat and has to be expelled in order to prevent the engine from catching fire. Most engines use water to this end. It enters the engine through seacock and a strainer. It is then sent to the cylinder head and block where it absorbs heat. The water is then mixed with the exhaust gas so that it can leave the boat safely.

But hot salt water some engines use is very corrosive. Additionally, the system can be so efficient that it causes the engine to not heat up to the desired operating temperature. Some advanced diesel engines use a more sophisticated cooling system and use a mix of fresh water and anti-freeze.

The overheat gauge will be the first to suggest that something went wrong. Additionally, you could notice steam in the engine compartment or lack of water from the exhaust. The engine may run uneven or stop completely.  If this happens, the first thing you want to check are the drive belts. Make sure that the belt that powers the raw water pump is not broken. If so, the only way to fix the issue is to replace the belt. You could either try to replace the belt yourself or hire a ship repair San Diego expert to fix it to replace it for you and check for any other underlying issues. Next, you should check if the strainer is clear and the seacock is open. Do this by shutting the seacock and removing the top of the strainer. Rinse the strainer and put the whole system back together. If you cannot see the blockage or if clearing the clog does not fix the issue, the raw water pump is likely broken. This often happens at the beginning of a season. In this case, you can replace the broken impeller, provided you have a spare one.

One of the most common and obvious issues with the fresh water cooling system is the lack of coolant. In this case, you should add more of it once the engine cools down. Be careful as the engine can be very hot and the hot water or steam can pour out, burning you along the way. Finally, you should check if the thermostat is working properly. A thermostat can get jammed, preventing fresh water flow when the engine is hot. You will likely have to replace it, but if you know how to remove it the engine should safely run without while you get the chance to dock.


The engine burns a lot of air for every liter of fuel. This is why it’s important that there are no restrictions to the air flow. If there are, the engine may start running rough, losing power or exhibiting a lot of black smoke.
Air filters are commonly housed inside a plastic or metal case, and you will have to remove it in order to inspect and change them. Paper filters have to be replaced, while foam or wire filters can be washed. However, the air filter may or may not be the cause of this issue. There could also be a clog in the vents or something that’s obstructing the air flow. You must also check if the engine is able to release the air by checking if any pipes are crushed or damaged.

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Phone: (619) 235-0961
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Phone: (619) 235-0961
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