Before you start
Gather the appropriate supplies and review the specific equipment manual.
- Engine manual
- Flashlight
- Temperature log
Step-by-step instructions
Reduce load and follow the engine manual
Check the actual alarm and temperature information; operate only as directed by the manufacturer.
Stop before damage occurs
If overheating persists or coolant is lost, shut down in a safe place after accounting for navigational hazards.
Check accessible raw-water clues
With the engine stopped, inspect the seawater strainer, intake obstruction indicators and hoses where safely reachable; do not open pressurized components.
Inspect belt and coolant clues once cooled
A failed impeller, slipping belt, low coolant, fouled exchanger or blocked elbow can look similar. Note findings rather than guessing.
Repair and verify
Have the cause corrected, then test under normal load and document stabilized temperature.
Safety note
Opening hot coolant systems can cause serious burns. Do not continue running an engine with a persistent overheating alarm.
Key takeaway
Confirm the cause rather than assuming every hot engine needs a new impeller.
Keep this job on your maintenance schedule
Save the topic as a maintenance task, choose a due date or engine-hour target, and record future service. Free and stored on your device.
Add to my maintenance plannerThis guide is for general education. Follow your equipment manufacturer’s instructions, current navigation guidance and applicable marine safety standards. When uncertain, use a qualified marine professional.