Common Causes Behind Marine Diesel Engine Overheating

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Similar to other engines, a marine diesel engine may also face overheating issues. A range of factors can be responsible for this problem.
Irrespective of the cause, continuing to run an overheated engine is a risk. It can severely damage the engine.
However, there are cooling systems installed to prevent overheating: Direct and indirect cooling. These systems depend on pumping the surrounding water either directly around the engine or around the sealed coolant.
When it comes to troubleshooting this problem, we first try to look at some common causes which can be easily rectified.
1. Problems with the drive belt
Drive belts power the water pumps for seawater intake. Any problem with a drive belt can slow down water movement, resulting in an overheated engine. Switch off the motor to check the drive belt quickly.
When belts are too loose, they will accelerate at high speeds. This may also cause the belt to slip away. Belts should be tensioned in a way that a 10kg pressure can only cause a movement of 10mm on the longest run.
2. Blocked seawater filter
Another problem could be blockage of filter by debris. The filter may be fitted as part of the skin fitting or as a separate unit of the pipework.
Clear the filter and restart the engine. Check the flow of cooling water from exhaust. Keep in mind that this may take 20 seconds to start.
If you find that the filter isn’t blocked, look for a plastic bag over the intake. This is highly possible if the ship was moving slowly or was stationary. Shutting off the diesel engine might result in the plastic bag flowing away, so you might not find the bag but get the cooling started again.
3. Damaged impeller
The impeller requires lubrication for proper movement which is provided by the pumped water. If it runs dry at high revs for even one minute, it might get damaged. Aging impeller will also cause the same problem.
You can inspect the impeller by removing the faceplate of the pump. If the impeller is damaged, replace it after removing broken elements (if any) of the existing one.
4. Insufficient coolant
Make sure there is sufficient cooler in the heat exchanger. Check by removing the filler cap after the system has cooled down sufficiently. Restart the engine and see if the problem is solved.
The indirect cooling engine has another pump responsible for circulating the coolant. Double check the belt to make sure it’s not affecting this pump’s movement.
5. Running at high revs
Over time, cooling waterways will narrow down, reducing the efficiency of cooling system. Other similar problems may occur, which will be exposed when the engine is operated at high revs for long time.
If you can’t identify the problem, this might just be it. You can lower it to moderate speed and see if the heating problem resolves.
If you find damaged or roughened parts, it’s better to replace them in time. We are marine engine spare parts suppliers providing quality heat exchangers and ship engine parts. Check out our products and services for more information.

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