How should I winterise the engine on an Arcona 400?

Winterise your Arcona 400 by changing the engine oil and filter, preparing the diesel supply, protecting the seawater cooling circuit and checking the antifreeze in the sealed coolant circuit. First identify the engine and saildrive from their plates, as replacement engines and production-year differences affect oil specifications, capacities and drain points.

Check the engine installation

Record the engine model, serial number and saildrive designation, then find the matching operator's manuals. Use these for oil grade, coolant type, filter numbers and tightening torques. The Arcona 400 model name alone does not establish those specifications.

Trace the seawater route from the intake seacock through the strainer, pump and heat exchanger to the exhaust injection elbow. Locate any additional coolers, low hose loops and the exhaust waterlock. These can hold water after the main circuit has drained.

Have the correct oil and fuel filters, replacement sealing washers, an oil extraction pump, coolant tester and suitable winterising antifreeze ready. If frost is forecast before you can finish, drain and protect the seawater circuit first.

Change oil and prepare fuel

Change the engine oil and filter a weekend or two before the season ends, so subsequent running circulates clean oil through the engine. Warm the engine normally, stop it, extract the old oil and replace the disposable filter. Lubricate the filter seal and tighten it according to the filter or engine instructions.

Refill to the specified level, run briefly and check for leaks. Recheck the dipstick once the oil has settled. Avoid overfilling: the published capacity may include oil your extraction pump has not removed.

• Drain water and sediment from the primary fuel separator into a clear container. Investigate persistent water, sludge or dark debris before storage.
• Replace fuel filters when due, then bleed and run the engine according to its manual. Resolve any starting problems before lay-up.
• Add diesel storage stabiliser at the labelled dose and run long enough to draw treated fuel through the system. Do not add methyl hydrate or petrol.
• Leave a conventional diesel tank nearly full to reduce the air space available for condensation. Retain expansion space and follow any tank-specific instructions.

Run the engine only with adequate cooling water and ventilation. Keep hands and clothing clear of belts and pulleys.

Protect both cooling circuits

The sealed coolant circuit and the seawater circuit need separate attention. With the engine cold, test the sealed coolant's freeze protection using a tester suited to its glycol type. Check the level and condition, and renew coolant if its service interval has expired. Do not mix incompatible coolant formulations.