Troubleshooting marine engines & drives
Choose a symptom. Start with the simple checks and stop when the job needs a workshop.
What's happening?
Drive knocks or vibrates
Troubleshoot unusual noises without confusing engine and drive faults. Check the propeller and visible mounts before workshop work on joints, bearings and the drive.
Engine not cooling – weak or no cooling water
Troubleshoot weak cooling water flow, from the intake and raw water strainer to the impeller and thermostat. Checks from Volvo Penta and Mercury MerCruiser.
Milky drive oil or oil leak
Milky drive oil can mean water ingress. Check the level and look for visible leaks safely, and have a workshop find the cause before running the boat again.
Temperature alarm – engine overheating
How to handle temperature alarms and tell low coolant apart from raw water flow problems. Start safely and avoid continuing to run the engine with an alarm.
Engine smokes or loses power
Troubleshoot smoke and power loss without swapping the turbo on a hunch. Start with load, propeller, air, fuel and oil level before a workshop diagnosis.
Engine won't start
Tell a starter motor that won't crank apart from an engine that cranks but won't fire. Check the controls, battery and fuel before calling in a workshop.