How should I winterize the engine on a Malö 36?

Winterise your Malö 36 by changing the engine oil and filter, checking frost protection in the closed cooling circuit, then flushing and protecting the seawater circuit. Check the engine identification plate first: the model and any replacement installation determine the correct fluids, quantities and drain points.

Identify and service the engine

Do not order a service kit from the boat model alone. A Volvo Penta MD2030 installation, for example, needs different service information from a later replacement engine. Record the full model suffix and serial number.

Before hauling out, run the engine under load until it reaches normal operating temperature. Warm oil extracts more easily and carries suspended contamination with it. Prolonged idling alongside is a poor substitute.

1. Stop the engine and extract the oil through the designated extraction tube or dipstick tube, as specified for the engine.
2. Replace the oil filter, lightly oiling the new sealing ring. Check that the old ring came away with the filter.
3. Refill with the specified diesel engine oil, using the dipstick to check the level rather than assuming a capacity.
4. Run briefly with cooling water supplied, check for leaks, then stop. Allow the oil to settle and recheck the level.

Check gearbox or saildrive oil separately, following the transmission manual's level-checking procedure. Investigate milky oil for water ingress before storage. Use the specified drain-plug torque and sealing washer; there is no reliable universal torque for these installations.

Protect both cooling circuits

A heat-exchanger-cooled diesel has two separate circuits: coolant inside the engine, and seawater passing through the heat exchanger and exhaust. Antifreeze in one does not protect the other.

Check the engine coolant with a tester suitable for its glycol type. A 50:50 mixture is common, but follow the engine and coolant manufacturers' specifications and use a frost rating suited to the storage location. Colour does not reliably identify coolant chemistry. Avoid mixing unknown products.

For the seawater circuit, have roughly 10 to 15 litres of correctly mixed winterising fluid ready, plus fresh water for flushing. This is a working allowance, not a stated Malö system capacity: hose runs, strainers, heat exchangers and exhaust waterlocks vary. Use a product suitable for marine engines and exhaust components, and check its dilution and actual freeze-protection rating.

1. Close the seawater inlet seacock and disconnect the intake hose at an accessible point downstream of it.
2. Arrange a bucket supply so the raw-water pump draws fresh water without running dry. Keep the bucket replenished while flushing.
3. Switch to the prepared winterising mixture and run briefly until it has displaced the flushing water throughout the circuit.
4. Stop before the bucket empties. Where practicable, check the discharged mixture's frost protection; colour alone cannot prove adequate concentration.