Boat and Engine Winterization – Step-by-Step Guide
Winterize your boat and engine – step by step
Frost, damp and leftover salt water are the most common causes of costly surprises in spring. Here is how to do it right – before and after haul-out, whatever your engine type.
Always follow the owner's manual. Drain points, oil capacities and winterization methods differ between engine brands and models. If in doubt – contact an authorized service workshop.
Three things that ruin an engine over winter
Frost damage
Water left in cooling passages, exhaust, filters and hoses expands as it freezes and can crack engine blocks, exhaust manifolds and pumps.
Corrosion
Salt, moisture and acidic old oil attack the engine's internal parts during the months the boat sits idle.
Stale fuel
Fuel breaks down over time, forms deposits and can absorb water. In diesel tanks, condensation can lead to diesel bug.
Four engine types – four different priorities
Outboard, 2-stroke
Flush with fresh water and spray fogging oil into the carburetor/air intake until the engine stalls.
Key: fogging oil
Outboard, 4-stroke
Flush, change oil and filter, drain the carburetor and fog the cylinders through the spark plug holes.
Key: oil change and carburetor
Inboard, raw-water cooled
The engine is cooled by raw water. The entire cooling system is flushed and filled with a glycol mixture.
Key: glycol in the entire cooling system
Inboard, freshwater cooled
Closed cooling circuit. Check the freezing point of the coolant and protect the raw-water side with glycol.
Key: check the freezing point
From haul-out to launch
Before haul-out
- Warm up the engine
- Change engine oil and oil filter
- Add fuel stabilizer
- Check the coolant
After haul-out
- Winterize the engine – 8 steps below
- Drain fresh water and protect the toilet from frost
- Take home batteries and textiles
During winter
- Check the boat after storms and snowfall
- Maintenance-charge the batteries
Before spring
- Replace impeller, filters and anodes in good time
- New cotter pin and check hose clamps
8 steps for the engine
The tag on each step shows which engines it applies to.
-
01
All engines
Flush the cooling system
Connect a flushing muff or drive bag and run on fresh water until the engine reaches operating temperature and the thermostat opens. Keep an eye on the tell-tale stream.
Motor flushers → -
02
Inboard
Fill with glycol
Run in a 50/50 mix of glycol and water until it comes out with the exhaust. Leave it in over winter.
Glycol → -
03
Petrol engines
Fog the cylinders
2-stroke: spray fogging oil into the carburetor until the engine stalls. 4-stroke and fuel-injected: spray into the cylinders through the spark plug holes.
Fogging oil → -
04
All engines
Drain carburetor and water separator
Drain the carburetor on 4-strokes and empty or replace the water-separating fuel filter so that no water can freeze.
Fuel filters → -
05
Outboards & sterndrives
Change gear and drive oil
Drain from the bottom, then fill new oil from the bottom until it runs out of the upper plug. Milky oil indicates water. Replace the seals.
Gear oil → -
06
All engines
Check the impeller
Remove the impeller and check its condition. Store it cool and dark – left compressed in the pump housing it can deform.
Impeller for your engine → -
07
All engines
Lubricate and protect against rust
Water-resistant marine grease in grease nipples and on moving parts. Contact spray on electrical connectors.
Marine grease → -
08
All engines
Propeller and anodes
Remove the propeller, check that no fishing line is wrapped around the shaft, and grease it. Replace anodes that are about 50 % consumed.
Anodes →
Glycol – three rules
The wrong glycol in the wrong place can do more harm than good.
Never mix types
Different types of glycol should not be mixed with each other.
Eco glycol where spills are possible
Use propylene glycol where the fluid could reach the environment.
Never ethylene glycol in fresh water
Applies to freshwater systems and the galley.
Boat checklist
- Fresh water: fully drain the tank, water heater, hoses and pumps.
- Toilet and holding tank: empty and protect with an eco-friendly antifreeze made for the purpose.
- Batteries: charge fully, disconnect the terminals, store cool and dry.
- Damp and mould: take cushions and textiles home, use a dehumidifier or moisture absorbers.
- Hull and bottom: wash at haul-out, check gelcoat, rudder and through-hull fittings.
- Cover: a tight tarpaulin or shrink wrap – but with ventilation.
Everything you need for winterization
Not sure which parts you need?
Contact us with your engine model or serial number and our customer service will help you find the right parts.
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