A clean paint job is not evidence of internal condition. Ask for a true cold start and arrive before the engine has been run. Verify the block is cold by touch only when safe.
Before starting
- Match serial numbers to documents.
- Review hours, service invoices, oil analyses and major repairs.
- Inspect oil, coolant and gearbox or saildrive fluid.
- Look below the engine for dried salt, coolant stains, diesel and fresh paint over corrosion.
- Inspect exhaust elbow, hoses, mounts, wiring, filters and access.
- Check saildrive diaphragm evidence or shaft-seal and bearing history.
Start and sea trial
Observe cranking speed, start time, smoke and alarm self-test. Monitor warm-up, charging, temperature, oil pressure and exhaust-water flow. Under load, verify full-throttle rpm against the manufacturer’s specified range and record rpm versus speed on reciprocal runs where practical.
Useful specialist tests
Oil analysis, cooling-system pressure test, exhaust back-pressure measurement, electronic fault history, crankcase pressure assessment, injector testing and compression or leak-down testing may be appropriate. Test choice should follow observed risk, not a standard shopping list.
A general pre-purchase marine survey may not include detailed mechanical diagnosis. Engage a suitable marine mechanic or engine surveyor and state the expected scope in writing. Price immediate catch-up service, undocumented diaphragm work, corroded exhaust, obsolete controls and poor access before negotiating.