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“Every winter, more people bring their outboard motors to us for servicing,” says Manuel Keinberger, managing director of Kiesow in Kappeln, a company specialising in the repair of boat engines. “These days, there’s less and less time for sailing, so people don’t want to risk long breaks from sailing because of their outboard motor.”
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During the warranty period, only an authorised workshop should carry out any work. After that, you can save yourself this expense – provided you have some DIY skills and have studied the manual thoroughly.
Changing the gearbox oil
Depending on the mileage, new oil is required every one to two years; if in doubt, change it every year. The 275-gram tube costs only around 13 euros. Place an oil pan under the engine, unscrew the drain plug at the bottom, then the vent screw above it. If the oil looks milky, as in the photo, water has got into the gearbox. There are various possible causes, such as a leaky hub, shaft or a tear in a seal ring. In this case, you should consult a specialist.
Removing the propeller
Check the shaft for corrosion. For motors with a shear pin, check whether a spare pin is available. For models with a vulcanised hub, check the rubber compound between the propeller and the shaft for cracks.
Check the impeller
The impeller is usually located in the lower part of the shaft and should be checked every two years. Don’t forget to disconnect it from the shift rod. An original replacement costs around 20 euros, but if it fails, the damage could cost many times that amount. This is because if parts get into the cooling channel, there is a risk of overheating leading to a seized piston – which spells the end for the engine. Refitting the shaft after replacement can be tricky. If in doubt, it’s best to leave this to a professional.
Impeller comparison
On the left of the picture is a new, genuine impeller; on the right is the dismantled one, where the vanes are on the verge of breaking off. Furthermore, the numerous burrs suggest that it is a cheap replica.
Check the intake strainer
This is usually located beneath the cavitation plate; on some models, it is also situated on the side of the shaft. Remove any debris such as pockmarks or sludge, otherwise the pump will not be able to draw in liquid without problems.
Grease the shaft
Once the lower part of the shaft has been screwed on, lubricate the shaft with waterproof grease and fit the propeller. Set the gear lever to neutral and check that the propeller turns freely by turning it; then secure the shift rod.
Secure the propeller
Tighten the lock nut only hand-tight; it is only intended to prevent the propeller from slipping off. Secure the nut with a split pin as shown.
Filling the gearbox with oil
Place the tube against the drain plug and squeeze in oil until it comes out of the bleed screw.
Check the spark plug
Deposits may indicate that the combustion is too cold or that the wrong oil is being used, for example in mopeds.
Corrosion protection
Add rust inhibitor to the remaining fuel. This will be drawn into the engine during the test run and will protect it.
Change the filter
With welded models such as this one, cleaning is not advisable; it is better to replace them.
Let it run idle
Start the engine in a suitable container of water, such as a builder’s bucket, and check that it is running and the gearbox is working. Cut off the fuel supply to allow the fuel lines to drain; just before the engine cuts out, pull the choke to burn off any remaining fuel.
Preserving the combustion chamber
Remove the spark plug again and spray the combustion chamber with a suitable anti-corrosion agent. Turn the propeller round a few times to distribute the agent. Ensure you switch off the ignition using the switch, otherwise it may be damaged. Then reinsert the spark plug.
Preserving the engine
Spray the power head and the electrical components with protective wax; spray the shaft and its moving parts with anti-corrosion protection; wipe off any excess oil.
Four-Stroke Extra
For four-stroke engines, the engine oil, oil filter and timing belt should be changed in accordance with the operating hours and the owner’s manual. These tasks, along with valve adjustment, are best left to a specialist workshop. Store the engine as described.
These products are recommended for maintenance
- Grease with high creep properties, for example for the suspension: 12.99 euros >> available here
- Brake cleaner for removing oil and grease residues: 6.80 euros >> available here
- Corrosion protection for fuel: 15.00 euros >> available here
- Gearbox oil: 8.83 euros >> available here
- Multipurpose oil for the water-repellent treatment of surfaces: 6.99 euros >> available here
- Marine engine internal preservative for the cylinder head: 14.29 euros >> available here
Lars Bolle
Chief Editor Digital