Why Is My Marine Diesel Engine Overheating? #
Marine diesel overheating can result from insufficient raw-water flow, poor heat transfer or a problem within the engine’s closed-loop cooling system.
Because several components work together to control engine temperature, overheating should be diagnosed as a complete system rather than by simply replacing one component.
Common Causes of Marine Diesel Overheating #
Possible causes include:
- Clogged sea strainer
- Damaged raw-water impeller
- Weak raw-water pump
- Restricted heat exchanger
- Fouled aftercooler
- Low coolant
- Coolant leaks
- Thermostat problems
- Deteriorated cooling hoses
- Restricted oil cooler
- Restricted transmission cooler
- Restricted exhaust mixing elbow
When Does the Engine Overheat? #
This is one of the most important diagnostic questions.
An engine that overheats shortly after startup may have a major loss of cooling-water flow.
An engine that operates normally at idle but begins overheating at cruising RPM may have enough cooling capacity for light operation but not enough once engine load increases.
That pattern may point toward restrictions in the heat exchanger, raw-water pump, coolers or other components.
Check Raw-Water Flow #
Changes in the amount of cooling water leaving the exhaust can sometimes provide a clue that raw-water flow has been reduced.
However, visible water at the exhaust does not necessarily prove the entire cooling system is operating correctly.
Avoid Continued Operation When Overheating #
Repeated operation at excessive temperature can result in much more serious engine damage.
If engine temperature continues to rise, safely reduce load and shut the engine down as appropriate.
All Tech Diesel provides complete Marine Diesel Cooling & Raw Water System diagnostics and service throughout Southwest Florida.
Is Your Marine Diesel Engine Running Hot? #
Tell us when the overheating occurs, what temperature you are seeing and any other symptoms you have noticed.
