Rigid Inflatable Boats : RIBS and Inflatables
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Tips on Winterising Outboard Engines
By: Robbie Smith
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Flush Engine


Drain Gearbox Oil


Fresh Gearbox Oil


Gearbox Oil Level


Remove & Check Spark Plugs


Spray In Fogging Oil


Grease Up


Tender Loving Care
Like most things mechanical and electrical a little bit of timely TLC goes a long way. To ensure that your outboard is ready to perform next season and that it keeps in top condition it’s very important to ensure it goes into hibernation properly. Just a few hours devotion is all that’s needed to ensure you protect your investment and reap the rewards of a straight forward start up when next spring arrives.

There are just seven simple steps to take, a few items to buy and a morning or afternoon to allocate! [ Caution: To avoid injury through accidental starting, be sure to remove the propeller from your outboard before proceeding.]

1. Flush Engine
You should flush saltwater out of the engine after each use, but we all know this often does not get done. Firstly you should thoroughly flush your engine with clean, freshwater and let the water completely drain from the engine. I prefer to purchase the optional ‘flushing plug’ which can be attached to a garden hose. This hose can then provide full water mains pressure for the flushing operation. Instead you can use a set of ‘ear muffs’ which again attaches to a garden hose and clamps on to the outboards lower unit covering the water intake ports.

Turn the garden hose on full before starting your engine. If using ‘ear muffs’ make sure that the water covers the inlet holes. Never run an outboard without cooling water, even for a short time - you can quickly ruin the water impeller and do serious damage to the engine. Run your outboard at normal idle speed for 5-10 minutes to allow the engine to warm up and to ensure your outboard is thoroughly flushed with clean freshwater.

After flushing the outboard, allow the water to completely drain from the engine. Your outboard should be in a vertical position for the water to completely drain. Shut off the engine by disconnecting the fuel line, in a no smoking area of course (see step 2 below). While you're waiting for your engine to drain, wash any dirt, grease, etc. from the exterior of the engine.

2. Drain Fuel
When you have completed flushing the engine, in step 1, disconnect the fuel line at the motor and continue running the engine until it runs out of fuel. Drain all fuel from the fuel hoses, fuel pump and carburetor. It is extremely important to ensure that all of the fuel has been drained from the carburetor otherwise any fuel/oil mixture remaining will evaporate and leave deposits (also called varnish, gum, etc.), in the carburetor. To drain the fuel from the carburetor you can use one of these techniques:

a) As the fuel begins to run out and the motor starts to ‘die’, choke the engine a little until the RPM picks back up. Continue choking the engine as the engine starts to die out until the fuel supply is finally exhausted.   -or-

b) Remove the drain screw from the carburetor bowl and allow all fuel to drain out. Replace the screw when finished. Although this technique requires a bit more effort than the first, it is recommended to use this procedure to fully ensure that all fuel has been removed from the carburetor.

Important: The new generation of fuel injected engines which have no carburetor should consider the use of putting fuel stabiliser in the system as it's not possible to to remove all the petrol from the system. The vapour separator should also be drained as part of the winterising procedure.

If your outboard is not an oil-injected model (i.e. you mix your petrol/oil manually), do not store the petrol for extended periods of time. Over time, the petrol and oil will separate which will lead to a lack of lubrication to your engine.

If you have fuel left in your tank you may want to add some fuel stabilizer to it, so that it can be used the following season. Fuel stabilizer will also help prevent condensation from forming in your fuel tank.

3. Storage Fogging Oil
Treat your outboard with ‘marine storage fogging oil’ which comes in an aerosol spray can and is used to prevent rust on the engine's cylinder, crankshaft, bearings, pistons, etc. and can be purchased at most local marine dealers. Follow the oil manufacturer's recommendation on the amount of ‘marine storage fogging oil’ to use (generally about 50ml for each cylinder).

First, remove the spark plug(s) and the stop switch lanyard cord from your outboard. It is also a good idea to disconnect the spark plug wires from the spark plugs to prevent accidental starting.

Manual Start Outboards:
Slowly turn the engine over a few times using the pull cord while spraying the storage oil into the spark plug holes.

Electric Start Outboards:
Be sure you have water hooked up to your water intakes before turning over your outboard to prevent damage to your water pump. While spraying the storage oil into the spark plug holes, turn the engine over in 5 second bursts using your electric starter. Do not over ‘crank’ your engine or you could damage the electric starter.

At this time it would also be a good idea to check your spark plugs. Check the condition of the electrodes and the electrode gap. Personally I would fit a complete set of new spark plugs if any of the remove ones looked as if deposits were starting to build up.

4. Change Oils
Change the gear oil in the lower unit. Oil not only loses it’s properties overtime but also collects minute particles during it’s circulation around the engine parts. Just see the metallic debris on those gear box plugs which use magnetic inserts. Also like fuel it also accumulates some water through condensation. Follow the step-by-step instructions in your outboard engines owners manual. Fresh oil to an engine is like cream to a cat, it will purr along nicely when changed. If you have a 4 stroke, change your engine oil and replace the oil filter.

5. Grease Up
Apply water resistant grease to propeller shaft, using a wheel bearing grease (or something similar), thoroughly grease the prop shaft and prop shaft threads. Also apply water resistant grease to all moving parts, joints, bolts, nuts, and plastic fittings.

6. Wax Up
To help keep your engine looking factory fresh, wax the exterior of your outboard using a high grade automobile wax.

7. Storage
Store the engine vertically in a dry area. If you store your boat on the water there are several schools of thoughts regarding whether you should store your engine in or out of the water. There are advantages and disadvantages of both ways and unfortunately there is no best way.

Factors such as temperature, salt/fresh water, algae growth, corrosion, etc. must be taken into account when deciding whether to leave your outboard in the water or tilt it up out of the water. To find out which is the preferred way ask your local marina and fellow boaters in your area, etc. how they store their boat/outboard during the off-season.

Factors to keep in mind:

  •   Storing in water allows algae and corrosion to affect your outboard;
  •   Storing out of the water could cause damage if the outside
      temperature reaches freezing and there is water in your lower unit;
  •   Storing down in the salt water drastically increases the potential for   corrosion.

Battery Storage

Battery condition is critical to the success of your first start up after winterisation. It's extremely important for fuel injected engines outboards which rely on constant battery power for the engine to function. What this means is that once started the battery has to be continually functioning. You can't remove the battery power like you can do for the 'old school' two-stroke' outboards.

i) Disconnect Battery

Disconnect the battery cables and clean the battery terminals using a wire brush.

ii) Recharge Battery
Recharge the battery to full strength. You should also recharge the battery once a month during the off-season to prevent electrical discharge and degradation of the electrolytes.    -or-    Better still consider the use of the latest Battery Float Charger systems.

iii) Clean Battery
Clean the exterior of the battery.

iv) Apply Grease
Apply grease (Vaseline works nicely) to the battery terminals.

v) Store Battery
Store your battery in a dry place.

October 2007

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