What is the best way to winterise the engine on an Arcona 340?
I am preparing to lay up my 2011 Arcona 340 for the winter ashore. It has the original Yanmar engine and saildrive. What is the exact sequence I should follow to make sure the block does not freeze and the engine is ready for next spring?
Answer
The best way to winterise the standard Yanmar 3YM20 or 3YM30 on your Arcona 340 is to change the engine oil and filters while warm, then flush the raw water cooling circuit with a marine antifreeze mix. Finally, service the saildrive by checking the gear oil for water ingress and replacing the zinc anodes.
Oil and Fuel Maintenance
Run the engine up to operating temperature so the oil thins out and suspends internal contaminants. Extract the oil via the dipstick tube using a vacuum pump like a Pela 6000. The Yanmar 3YM20 takes 2.7 litres of 15W-40 mineral oil. The 3YM30 takes 2.8 litres. Change the oil filter (Yanmar part 119305-35170, typically around £12). Smear a little fresh oil on the rubber gasket and tighten it firmly by hand.
Replace the secondary fuel filter located on the engine block (Yanmar part 104500-55710). Top the stainless steel fuel tank up to 95% capacity to prevent winter condensation. Add a dose of marine biocide like Grotamar 71. Drain a small amount of diesel from the bottom of the primary Racor filter bowl to check for water or dark sludge.
Flushing the Raw Water Circuit
Close the raw water seacock fully before removing the inlet hose to prevent flooding. Disconnect the heavy reinforced hose from the seacock. Place the end into a large bucket. Run a hosepipe into the bucket to provide a steady supply of fresh water.
Start the engine and let it run for ten to fifteen minutes. The engine must get hot enough for the thermostat to open. This ensures fresh water flushes the entire block and heat exchanger. Turn off the hosepipe. Pour 5 litres of pre-mixed propylene glycol marine antifreeze (rated to at least minus 20°C) into the bucket. Run the engine until brightly coloured antifreeze spits out of the exhaust at the transom. Shut the engine down immediately. This process pushes antifreeze into the plastic Vetus waterlock silencer in the aft locker, protecting it from cracking in freezing temperatures.
Saildrive and Anode Maintenance
The Arcona 340 usually features a Yanmar SD20 saildrive. Once the boat is lifted ashore, place a pan under the leg and crack the lower drain plug. Inspect the first few drops of gear oil. Milky oil indicates failed propeller shaft seals that require replacement before spring. If the oil is clear, remove the top dipstick and drain the remaining oil. Refill from the top with 2.2 litres of Quicksilver High Performance SAE 90 gear oil until it reaches the upper mark.