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How to winterise your outboard engine

Your outboard engine should be winterised and protected against corrosion before the end of the season. Winterising your outboard correctly is the best way to ensure it has a long life. We take you through the process of winterising your outboard, step by step, and answer the most important questions.

How to winterise and protect your outboard - checklist:

For reasons of safety, (and peace of mind) always make sure your outboard is held firmly in place.

  1. Either remove your outboard completely and support it with blocks or place it on something like a stand or transport rack
  2. Alternatively, if you're taking the whole boat out of the water for winter, leave it bolted in place and use our outboard motor brackets.

Flushing your outboard

For tips on how to flush your outboard, take a look at our guide „How to clean, care for and maintain your outboard“.

Emptying & protecting the carburettor

  1. Keep the engine running, and remove the fuel line.
  2. Before the engine stalls, spray anticorrosive oil (fogging oil) into the carburettor and pull the choke until the engine runs out of fuel and stops. Remove the air filter, if there is one, before doing this.

Note: Refer to the outboard motor operating manual for more information.

Check the condition of the spark plug

How do you maintain the spark plug on an outboard?

How to change the spark plug on your outboard:
Check the spark plugs once a year. Just before winter storage is the perfect time to do this. Use a special tool to remove the spark plug and spray engine interior preserver into the combustion chamber while doing so. The lower end of the spark plug should be clean. Black electrodes or deposits will result in a loss of power. Wet spark plugs or oil residues are an indication that the carburettor mixture is too rich (higher fuel to air ratio). Clean the spark plug (e.g. with a small wire brush) and check the gap between the two electrodes. This should be 0.7-0.9 millimetres. Over time, this gap will increase. A bigger gap is a sign that the spark plug should be replaced promptly.

How to clean your spark plug

  1. Wipe the area around the plug.
  2. Remove the spark plug using a special socket wrench
  3. Use a wire brush to clean off any oil and rust deposits.
    Tip: The smaller the brush, the easier it is to clean the spark plug.
    Note: Do not press too hard on the spark plug with the brush, otherwise the electrodes may bend.
  4. Spray brake cleaner on the plug and wipe it with a cloth.
  5. Inspect the spark plug for debris & damage.
  6. Measure the distance between the electrodes.
  7. Replace the spark plug or put your cleaned spark plug back.

Changing the fuel filter on outboards

What is the purpose of a fuel filter on outboards?

A fuel filter or petrol filter for outboard motors is used to filter impurities such as dirt particles and sometimes water from the fuel before they reach the engine. Contaminants from the tank and fuel are quickly deposited in the fuel filter, in particular when fuel containing ethanol is used. The filter is designed to prevent contaminants from entering the engine and causing damage.

Where is the fuel filter on an outboard motor?

The exact location of the fuel filter depends on the outboard and the filter. Refer to your manual to determine the location of your filter. A fuel filter may be a single component in the engine housing or screwed onto the motor. In-line filters are also available. The difference here is that these are used in the fuel line between the tank and the fuel pump.

How often must the fuel filter of an outboard motor be changed?

The number of times a fuel filter needs to be changed depends on how the outboard motor is used, i.e., for private or commercial use, whether the outboard gets used a lot or little. Signs that a change is necessary include contamination in the filter. Since the filter is transparent, these are easily visible from the outside. A smoking engine and loss of power are also signs that the fuel filter needs to be changed.

Can you clean outboard fuel filters?

Depending on type of fuel filters, it can be cleaned. Fuel filters made of paper and nylon should not be cleaned, but replaced immediately. Filters made of metal can be cleaned by cleaning the screens.

Why should you change your fuel filter on your outboard?

When the pores of the filter are clogged up, not enough fuel can flow through, which can lead to a loss of power of the engine, or in the worst case, to a total failure. The outboard fuel filter should therefore be replaced from time to time. When winterising your outboard, it is always a good idea to check the filter, clean it and replace if necessary.

Motor care

How to change the fuel filter of your outboard motor:

The procedure and the tools required for changing vary depending on the manufacturer of your outboard motor. In most cases, an explanation of how to change the fuel filter is given in your outboard manual.

However, the following is a general procedure for changing fuel filters:

  1. Place a bowl under the filter and have a cloth ready to catch any petrol that may leak out.
  2. Use a filter wrench or filter belt to make it easier to loosen and remove.
  3. Make sure that the rubber seal is positioned correctly.
  4. Coat the contact surfaces with a little oil to prevent the seal from moving.
  5. Fit the new fuel filter so that it is hand-tight.
  6. Run the engine for a few minutes to allow new petrol to flow through.
  7. Check the filter for leaks.
  8. If there are leaks, either re-tighten the petrol filter, correct the seal or replace the filter.
  9. Your motor is now ready to be used.

Changing an in-line fuel filter on an outboard motor:

  1. Place a bowl under the filter and have a cloth ready to catch any petrol that may leak out.
  2. Remove any clamps from the hose lines.
  3. Install the new in-line filter.
    Note: Watch out for the direction of flow, which is usually marked with an arrow on the filter.
  4. Replace the clamps and tighten them.
    Note: Be careful not to overtighten the clamps.
  5. Run the engine for a few minutes to allow new petrol to flow through the filter.
  6. Check the filter for leaks.
  7. If there are leaks, either tighten the petrol filter again or replace the filter.
  8. Your motor is now ready to be used.

Tip: We recommend installing an additional petrol filter between the engine and the tank to keep maintenance to a minimum, even if your outboard motor already has an integrated petrol filter. This extra filter, an inline filter, is installed in the hose line. If you're unsure how to change the filter, you should take your engine to a dealer and ask them to do it for you.

Protecting the combustion chamber against corrosion

To protect the combustion chamber of an outboard motor from rust deposits / flash rust (oxidation / corrosion), the combustion chamber should be preserved for storage:

  1. Remove the spark plug.
  2. Spray some anti corrosion oil into the combustion chamber through the spark plug hole. in-line fuel filter16742
  3. To make sure the oil is well distributed, slowly pull the starter cord a few times with the stop button pressed, or push the starter button to otherwise cycle the engine several times.
  4. Fit the spark plug.

Inspecting the outboard propeller

Before winterising the outboard motor, the propeller should be checked for damage and replaced if necessary. Do this as follows:

  1. Inspect your propeller for damage, such as bent blades, damage to the shear pin, and check the cotter pin is in place, making sure you also have a fresh cotter pin on hand.
  2. Change the propeller if necessary.
  3. Inspect the shaft for corrosion.
  4. Lubricate the shaft with a seawater-resistant grease.
  5. Reinstall the propeller.

Tipp: The best way to examine the propeller is to dismantle it. We can also provide you with replacement propellers, which should always be kept on hand for extra safety.

Checking sacrificial anodes

Sacrificial anodes protect the outboard from corrosion by 'sacrificing' themselves, so that the higher quality material surrounding them does not corrode. It is therefore important to have a sufficient number and quality of anodes on your motor and to check and renew them regularly. The off season is the perfect time to do this.

  1. Check and inspect your zinc anodes/aluminium anodes/magnesium anodes, which protect the motor from corrosion, to see if they are diminished.
    Note: Where your anodes are located and how many there are depends, among other things, on the size of the motor. Anodes are usually located on or under the cavitation plate and on the transom of your outboard motor.
  2. Your anodes should be replaced if only 2/3 are left and they have corroded to half the original size.

Tip: It is usually necessary to change sacrificial anodes once per season, although this depends on the number of hours the motor has been driven, and other factors.

Anodes

Examining the fuel line and rubber parts

Heat and UV rays can damage rubber parts on the engine, such as the fuel line.

  1. Inspect the fuel line and rubber components for wear before winterising your outboard motor.
  2. If there are kinks, hardening or porous spots, replace the part in question.
  3. Examine the relevant hose clamps. These should not be rusted, must be tight, but not over tight.
    Note: Moving parts such as throttle levers, cables and the engine mounting clamp bolts should move smoothly.
  4. Clean the parts if possible and re-grease them if necessary.

Checking components & lubricating moving parts

  1. Inspect auxiliary equipment of your outboard motor before winter storage. This includes the drive shaft, cables, throttle lever and clamping screws.
  2. Clean these parts with a cloth if necessary.
  3. Remove old grease residues with brake cleaner.
  4. Lubricate all visible moving parts with waterproof grease. You will need a grease gun for the grease fittings, grease nipples, or Zerk fittings (metal fitting used to feed marine lubricating grease into a bearing under moderate to high pressure).

Tip: Remove your outboard motor propeller to make the job easier and faster.

Changing the engine oil on an outboard motor

Changing the engine oil of the outboard motor is usually explained in your manual and must be done once a year, preferably when winterising the outboard motor for 4-stroke engines. To do this, you often only need a Phillips and slotted screwdriver.

  1. Loosen the engine oil drain plug.
  2. Loosen the filler neck.
  3. Catch the engine oil with a bowl or similar.
  4. Drain it all out.
  5. Fit a new seal to the drain plug and refit it.
  6. Fill up with engine oil via the filler neck.
    Tip: You can check the quantity using the dipstick or sightglass.
  7. Always check the oil level again after a short test run.

Changing gear oil on outboards

Once a year, at the end of the season, you should change the outboard gear oil, as water can collect here and cause damage during winter storage.
Changing the gear oil of the outboard motor is usually explained in your manual. To do this, you often only need a Phillips and slotted screwdriver.

  1. Place a container under the lower oil screw.
  2. Loosen the lower oil screw first and then the upper bleed screw.
  3. Catch the oil that comes out in a drain pan.
    - if the oil is a milky-light colour, this indicates water
    - If the oil is silvery or grey, there may be a mechanical problem.
    Note: Contact a service technician to determine the cause.
  4. Let the oil drain out completely.
  5. Fit new seals to the oil drain plugs.
  6. If the oil is its usual colour, squeeze new gear oil into the lower screw opening until it comes out bubble-free at the top of the bleed screw opening.
  7. Close the oil and bleed plug.

Note: You must dispose of used oil correctly.

Inspecting the outboard impeller

The impeller is used to keep the engine cool with seawater.

  1. Before winterising your outboard, check that your impeller is working properly.
  2. Signs that the impeller needs to be changed are a reduced stream of water at the cooling water outlet or when the outboard shows signs of overheating.

Note: The impeller is usually located in the lower part of the engine shaft.

How often must the impeller be changed on outboards?

Changing the impeller, which should be done regularly every few years on an outboard motor, requires some practice, but can be done by yourself. The recommended replacement interval for impellers can be found in the service schedule.

Cleaning and protecting the outside of your outboard motor against corrosion

  1. Before winterising, remove dirt such as dust, bird droppings and any algae from your outboard motor with a damp sponge and some washing-up liquid.
  2. Check the exterior of the engine for scratches, leaks and rust spots and repair them before the winter break.
    Note: Any dirty water must be collected in a separate container or tank and should not be emptied into the sewage system, the harbour or dumped on the floor, as there may be oil residues in the dirty water.
  3. To preserve the engine, spray the cleaned engine with corrosion protection. Spraying just a light mist on all metallic parts will protect your outboard from flash rust during winter storage.

Storing your outboard motor in the off season

Once your motor is dry and held securely ready for winter storage, you can now plan the next season in peace over the next few months.

Note: Your motor can be stored upright, but also lying on its side. For more details about how to transport your outboard take a look at our guide „Starting your outboard, fuelling and transporting“.

Note: If storing your outboard motor under a tarpaulin, make sure that the air can circulate. Further and more detailed information can be found in your outboard motor manuals.

You can find out how to winterise your diesel boat engine in our guide Diesel motor care and maintenance.

Written by our SVB (technical) experts

Written by our SVB (technical) experts

Our team of SVB technical experts is there to give our customers professional advice on all matters relating to technology on board. Their expertise is the result of regular training and many years of experience.