Winterising your inboard diesel engine can be completed in 12 easy steps!

1. If you have a diesel inboard engine and it has been running well all season, then the first thing to do is to fill the fuel tank right up to the top. This should be done carefully so you can see the fuel come up the filler tube. There is a good reason for doing this practice. If the tank is not completely full there will be an air gap between the fuel and the top of the tank. This will lead to condensation caused by the cold weather during the winter. Diesel bug thrives in these conditions. Add a small amount of biocide (fuel additive),such as Racor Diesel, or Marine 16, to kill the bug.

2.  Next ensure the fuel cap seals properly by smearing the thread with either grease or petroleum jelly (Vaseline). This will stop moisture entering the tank as well as making the cap easier to open in March.

3.  Locate the fuel filter and drain into a clear plastic bottle. If you use a fairly large bottle you will also capture the filter making it less messy to clean up later! Refit the new filter and bleed the fuel system to ensure there are no air bubbles in it. However, if your engine has not been running well all season then do not top up the fuel tank to full. Instead, drain the remainder of the tank and flush it out. Once cleaned, the tank can be filled with fresh new diesel right to the top of the tank.

4.  This stage involves a bit of work. Changing the engine oil. If you run the engine until it reaches its normal temperature, the oil will flow easier. Next remove the dip stick and insert Vacuum pump down it. Pump continually to suck up the oil from the sump – this is the cleanest way to remove the old oil but requires energy on your part to do it! When you are sure it is all out ( measure the quantity removed). Replace with new fresh clean oil.
5.  If you did not get messy changing the oil, you will be after you change the oil filter! Use a special tool for undoing the filter. A Filter wrench will do the job. Try to get a basin or tray under the filter to catch the oil as you undo it.It is important to change the oil filter each season as impurities such as carbon build up and restrict the flow of oil.

6.  Most marine diesel engines are fresh water cooled using a heat exchanger. Just like in a car, it needs anti-freeze added each winter. This needs to be the correct mixture. So drain off the old water and refill with the recommended levels of water and anti-freeze. This will prevent corrosion in the water ways of the engine and the water freezing!

7.  The salt water cooling also needs attention. Locate the salt water intake pump and open it up. Remove the impeller. Just before you are ready to put the boat back in the water, install a new impeller into the pump. Do this each season because it wears easily and becomes less effective as the season goes by.

8.  Loosen the rubber drive belts from the flywheel or alternator etc. Keeping the tension on these belts while in a stationary position all winter is not good for them. They may start to crack. If they look as if cracks are there, then wait until the launch date and replace them.

9.  Block off the water inlet with a wooden plug, to prevent moisture entering the engine. Then use a rag to block off the exhaust pipe. Again to prevent moisture.

10. Disconnect the battery. Take it home and put in a dry place, like the garage. Clean the battery casing and then put it on charge. Once fully charged keep the cell levels topped up and charge each 4 weeks during the winter. Write on the calendar – charge boat battery. So you will remember! If your boat battery is over 5 years old, I would recommend you replace it with a new one.

11.  Once you have done all of the above you should thoroughly clean the engine. Remove all small pieces of debris that might have collected on it. Use a lubricating spray oil to provide a barrier for moisture and prevent corrosion.

12.  Finally, clean around the engine, in the bilges and either side. Use a good cleaning liquid to remove oil stains etc. You will feel you have done a great job when it is all finished and looking good!