Seaway Engine Winterisation

Seaway can provide you a complete winterisation of your engine as part of our ongoing care.

If you are planning on decommissioning over the winter, then it is important that you winterise your engine properly.

Winterisation incorporates a minor engine service. Partly done in the autumn and partly done in the spring just before re-launch.

There are different levels of winterisation depending on the boat or the engine, this should be done in line with the manufacturers’ recommendations.

Seaway 11 Quick Points To Winterise Your Engine.

Fill your diesel tank.

This is to reduce condensation in the tank over the winter. Ensure water does not enter the fuel tank as the interface between water and fuel is where diesel bug thrives. If you suspect signs of the bug then this would be a good time to add a fuel additive to keep it under control.

Check the fuel filler cap seal.

A new O ring around the filler cap is vital to stop any rain from getting into the tank this way. Applying something such as vaseline on the threads will help the removal of the filler cap.

Pre Filter drain check and change.

This is important, as you can examine the quality of the fuel easily. Using a clear small receptacle, such as a cut in half water bottle, any signs of water / contaminants can be seen. If there are problems, then you can put into action a plan to solve this. Using known clean fuel is difficult to establish. A busy marina / fuel dock is likely to have clean fuel. The tanks can be drained & filtered fairly easily. If your tanks need cleaning, this is not so easy!

Change the engine oil.

Changing the engine oil removes the corrosive acids produced during combustion. Clean oil in the engine will prevent harmful acids in the engine during the whole of the winter.

Change the oil filter.

Changing the filter is important when the oil is changed as this is where and any swarf, carbon deposits and other combustion products build up. Over time, these deposits restrict the flow of oil in your engine. This should be a minimum of once a year.

Antifreeze / Fresh Water check.

Make sure that you have the right ratio of water to Anti-freeze. If you have been topping up with water all season you should drain the system and top up with the correct mixture. The engine manufacture will recommend that the system is drained at a particular service interval. This is because antifreeze / coolant not only helps protect against the cold, but also it is a corrosion inhibitor for the internal small waterways within your engine.

Remove the impeller.

This is to stop your impeller from becoming deformed by remaining in the same position for a long period of time. When this happens, it becomes less effective and may break apart.

Remove the drive belts.

This is to stop the belt from remaining in the same position for a long period of time. This is a good time to check the condition of the belt. If it is worn or there is a lot of black belt dust on the engine, this is indicative of it slipping.

Clean and inspect.

Give your engine a good clean and inspection all over. You are checking for anything amiss, jubilee clips for corrosion, electrical wiring for corrosion and chafe and any water, fuel or oil leaks. Cleaning the bilges make it easier to notice any leaks. Finally after wiping down the engine, coat it with duck oil or a corrosion block.


It is best to remove and recharge these, checking water levels where applicable. Your battery condition can be checked by a hydrometer, this measures the specific gravity of them and it is immediately if a cell is not performing. If your batteries are 4 years old or more then it might be time to think about replacing them.

Exhaust and Inlet.

It is a good idea to block off the exhaust and if possible the air inlet to the engine to prevent moisture entering and nesting birds!

If you would like any assistance with this, we would be happy to provide this as part of our service.