How should I winterise the engine on a Hallberg-Rassy 36?

Winterise your Hallberg-Rassy 36 by changing the engine oil and filter, checking the closed-circuit coolant's frost protection, then flushing and protecting the seawater circuit with suitable antifreeze. First identify the engine from its plate: many HR 36s have Volvo Penta MD22-family engines, but replacements and installation differences mean you must take oil quantities, coolant specifications and drain points from your engine's manual.

Check both cooling circuits

A freshwater-cooled diesel has two separate cooling circuits. Coolant circulates through the engine and heat exchanger; seawater passes through the strainer, raw-water pump and heat exchanger before entering the exhaust elbow. Protecting one circuit does not protect the other.

Before buying supplies, record the engine model and serial number, then check:

• Engine coolant: test its freeze protection with a tester suitable for that coolant. Choose protection below the lowest expected winter temperature; around minus 25°C to minus 35°C is a sensible target for many northern European lay-ups.
• Coolant condition: replace it if overdue, contaminated or of unknown specification. Colour alone does not identify compatibility; do not mix different coolant technologies.
• Seawater installation: trace the intake seacock, strainer, pump, heat exchanger, anti-siphon valve and exhaust waterlock, noting any separate drains.
• Leaks and wear: inspect hose ends, clips, pump seals, belts and the exhaust mixing elbow before laying up.

If the engine has been converted to direct seawater cooling, follow its instructions for the thermostat and block-draining procedure.

Change the oil warm

Change the oil before the final cooling-system treatment. Used oil contains combustion residues and moisture. Leave clean oil in the engine over winter rather than postponing the change until spring.

1. Run the engine to normal operating temperature with its cooling-water supply connected.
2. Stop it and extract the warm oil through the designated extraction tube or dipstick tube, following the manual.
3. Replace the oil filter, checking that the old sealing ring comes away. Lubricate the new seal and tighten as specified on the filter or in the manual.
4. Refill with the specified diesel-engine oil, using the dipstick to establish the final level.
5. Run briefly and check oil pressure and leaks. Stop, allow the oil to settle and recheck the level.

Check gearbox oil separately: it has its own lubricant specification and service interval. Service the fuel filters as required, drain water from the separator and bleed the fuel system before the final engine run.