Winterisation: Inboard Engines

‘Winterising’ an engine is a key maintenance task for any boat owner.  Failure to do so could mean more work in the Spring and potentially more expensive repairs should things go wrong.

Your local engineer will be able to advise you on the necessary tasks that need to be carried out to prepare your engine.  You should also find these listed in your Owner’s manual.  However, as a general rule, it is recommended that the following procedures should be carried out:

• Check your coolant! Vital to protect the inside of your engine, most of the time, it is recommended that the mixture is 50% water and 50% anti-freeze, though, check in your manual or with your engine manufacturer.
• Perform an oil change! Bring the engine up to temperature to ensure the oil is hot.  Replace the oil filter.
• Flush your raw water system! Close the seacock and disconnect the hose on the outlet side of the raw water pump.  Disconnect the cooling water discharge hose from the exhaust manifold or riser.  Run fresh water into the discharge hose to back-flush raw water passages and rinse out salt deposits.  You can extend the disconnected pump hose outside the boat or let the bilge pump handle the flush discharge.  Remove and rinse the impeller.  It is probably best to leave it out until spring, in a dry place, sheltered from light to avoid premature cracking and ensure it’s good to go for the next season.
• Make your engine air tight! To avoid moistuse getting inside your engine, ensure you seal your air inlets, crankcase and transmission breathers, exhaust outlets and tank vents by creating an airtight seal.  Making caps from plastic containers and then taping them into place is an ideal solution, or see if someone you know has a 3D printer!
• Release belt tension! Slacken the alternator adjuster to release the tension on the drive belt, helping to prolong the life of the belt. A belt sat for too long in one position is likely to stress it in the tight spots resulting in premature wear and cracking occurring.
• Drain the waterlock and exhaust system! The less moisture the engine is exposed to, the less corrosion will occur.
• Dry the bilge! This is a mucky job but well worth doing to avoid leaving a lot of moisture which is liable to corrode the engine and other important parts within your boat.
• Stop corrosion in it’s tracks! This will help safeguard against corrosion. Some products which we can recommend are ACF50/Corrosion Block, Contact Spray or Dielectric Grease for electrical connections, WD40 or similar for Moisture Displacement and general protection and Red Rubber greases/silicone grease to protect rubberised components. Never use Petroleum/Oil derived greases on rubber components.
• Fill the Fuel Tank! This will help avoid condensation. Where there is air, especially inside an enclosed space, moisture will accumulate.  Tighten the deck filler also, as water can puddle when the boat is ashore.

The same rules generally apply to outboards, too! Albeit, some of the steps above may be simpler or have slight variations to the process. If in doubt, consult your manual or the manufacturer.