What Should You Do if a Marine Diesel Engine Overheats? #
If a marine diesel engine begins overheating, the first priority is preventing additional engine damage.
Excessive operating temperature can damage cylinder heads, gaskets, seals and other internal engine components.
Reduce Engine Load #
If conditions allow, reduce RPM and monitor the engine temperature.
If temperature continues climbing, shut the engine down when it is safe to do so.
Do not continue operating simply because the engine has not yet triggered an automatic shutdown.
Check for Obvious Cooling Problems #
Once the engine has been safely stopped, some basic conditions may be checked.
Possible issues include:
- Clogged sea strainer
- Low coolant
- Visible coolant leak
- Damaged cooling hose
- Reduced exhaust-water flow
- Obvious raw-water problems
Use caution around a hot engine.
Do not open a pressurized cooling system while it is hot.
Do Not Assume the Impeller Is the Only Possible Cause #
A failed impeller is a common cause of marine overheating, but it is far from the only one.
Other possibilities include:
- Weak raw-water pump
- Restricted heat exchanger
- Fouled aftercooler
- Thermostat problem
- Restricted cooler
- Coolant-circulation problem
- Exhaust mixing-elbow restriction
Repeatedly replacing the impeller without checking the rest of the cooling system can leave the underlying problem unresolved.
Learn more about our Marine Diesel Cooling & Raw Water System services.
For urgent problems, see our Emergency Mobile Marine Diesel Service.
