Why winterize?
Water that freezes in the cooling system can crack the block, heat exchanger and pumps. Old oil and moisture cause corrosion over the winter. Fuel breaks down over time and can leave deposits that cause starting problems. A winterized engine starts more easily in spring.
Winterizing involves more than draining water from the engine: changing oil and filters, cleaning and inspection, lubricating moving parts and sometimes adding fuel stabilizer.
Before you start
- Get out the owner's manual for your specific engine. Always follow the engine manufacturer's manual.
- Run the engine until it is warm (on land with a flushing connection, or in the water before haul-out).
- Have oil, filters, antifreeze, a bucket and rags ready.
Inboards (diesel and petrol)
- Change the engine oil and oil filter while the engine is warm.
- Change the fuel filter and water separator; fill the tank to reduce condensation.
- Freshwater-cooled engines: check the coolant's antifreeze protection.
- Raw water system: let the engine draw in antifreeze until it comes out of the exhaust, or drain the system according to the owner's manual.
- Remove the impeller and store it dry.
- Petrol: fog the cylinders with fogging oil if the manufacturer specifies it.
- Check anodes, belts and hoses.
Outboard
- Flush the engine with fresh water via the flushing port or flushing muffs.
- Run the carburettor dry or add fuel stabiliser, as recommended by the manufacturer.
- Change the gearcase oil and check the old oil for water (milky colour).
- Grease according to the lubrication schedule and spray fogging oil into the spark plug holes if the manual says so.
- Store the engine upright so that water drains out.
Battery and electrics
- Fully charge the batteries and disconnect the negative terminal.
- Check the charge during storage according to the battery manufacturer's instructions.
- Drain the fresh water system and water heater, or protect them with antifreeze.
- Close the seacocks and leave a note by the engine listing what you've done.
Let the boatyard do it
Boatyards may offer engine winterization and draining of the water system as separate services. Mälaröarnas Båtvarv publishes separate prices for each job. Ask what your quote includes.
Not sure about your engine? Ask for a quote on winterization. Give the engine make, model and serial number so the quote is right from the start.
Frequently asked questions
When should you winterize your boat engine?
Before the first frosty night, usually when the boat is hauled out. The cooling system must be drained or filled with antifreeze before the water can freeze.
Do I have to change the oil in the autumn?
Yes, most manufacturers recommend changing the oil before winter storage so that acidic, dirty oil doesn't sit in the engine all winter. Always follow the engine manufacturer's owner's manual.
Can the boatyard winterise the engine for me?
Yes. Many boatyards sell winterisation as a separate service, sometimes mandatory for indoor storage. Ask for a written quote listing what's included.
Should the impeller stay in over winter?
Many people remove the impeller so the rubber doesn't take the shape of the pump housing. Check what your engine's owner's manual says.
Is draining the water from the cooling system enough?
No. Winterizing also includes changing the oil and filters, lubricating moving parts and protecting the fuel system. Always follow the engine manufacturer's owner's manual.
Sources
- Vinterkonservering av din båtmotor, Biltema biltema.se
- Support och instruktionsböcker, Volvo Penta volvopenta.com
- Vinterförvaring, priser (obligatorisk konservering), Mälaröarnas Båtvarv malaroarnasbatvarv.se