Marine Diesel Engine Winterisation

FRESH WATER / ANTI FREEZE DIESEL ENGINE WINTERISATION

Tools & Consumables

• Anti Freeze (check manual for quantity)
• Distilled water  (check manual for quantity)
• Socket or wrench for the fresh water drain plug
• Measuring jug
• Wet vac (Contaminated oily bilge water should be disposed of in an oil recycle facility…so we usually want to avoid dropping more fluids to the bilge).

I change the coolant every December, although most manufacturers recommend changing it every 2-5 year. Check your manual.

This job is easiest to do while the boat is still afloat. Check the strength of any anti freeze required. Run the engine up too operating temperature to open the thermostat. If you’re impatient and choose to rev in neutral then don’t go over 1,500 RPM (plus consult your manual). Once the engine is up to operating temperature and run for another few minutes or so, close down the engine and drain the coolant system. If you open the heat exchanger cap it will allow air in while you drain from the bottom. Some people use a wet vac for this task but this makes it much harder to measure the amount you have removed. If you have an external expansion tank it will need drained at the same time.

Once all of the coolant is drained, close the drain valve and mix up the new coolant. Typically this is 50% anti freeze and 50% distilled water, however check the instructions on the anti freeze bottle with regards to expected lowest temperatures. A good trick here is to measure how much coolant you have drained off and make up the same quantity before topping up.

Once you have topped up, leave the heat exchanger cap (filler cap or expansion tank cap) off, re start the engine and run for a few minutes keeping an eye on the coolant level, this will help force any air locks (that you have inadvertently trapped in the system) to the top. You may need to top up a few times to get back to the correct level. If you have an expansion tank, ensure this is filled up to the “cold” level as well.

A good friend of mine varies this procedure. He uses an anti freeze tester (hygrometer) to check the anti freeze mix pre winter and then decides whether he actually replace or tops up anti freeze. I prefer to simply change anti freeze annually and ensure the corrosion inhibiter content is new.

OIL & OIL FILTER CHANGE

Tools

• Permanent marker pen
• Oil pump or oil change vacuum extractor
• Filter wrench or strap wrench
• Sealable containers for the old oil
• Small receptacle for catching oil under the filter
• New oil (check the manual for grade and quantity)
• Replacement filter with O ring seal
• Rags
• Oil absorbent pad (just in case)
• Blue roll (or strong kitchen roll)
• Gloves / barrier cream

The oil change is a key component of diesel engine winterisation. Ideally carry this stage out before you lift the boat ashore. Run the engine up to operating temperate (in gear) and then close it down, (Diesel engines should be run in gear under some load (for example when charging) to avoid glazing (coking up) the bores. The hotter the oil is, the less viscous it is and the easier it is to extract. If you don’t run it up first it is very hard to extract the oil. Think ahead as to the quality of receptacle for hot oil.   Drain or suck the oil out. I use an engine oil extractor (or oil pump) which sucks oil up through the dipstick tube.  Open the oil filler cap to allow air in to replace extracted oil. Before you start make sure you have enough sealable container to suck/pump the old oil into. The old oil will probably be black (which is why it needs changing). If during extraction you discover a milky/white oil this indicates water has got into your oil and further investigation is therefore required before you proceed When you get to the last few dregs try moving the end of the extraction tube up and down the sump to catch any oil at the lowest point. There will always be a few drops left in the sump, but that will be diluted by the new oil when added shortly.

Take the new filter and read the side to see how much it should be tightened. Record the date on the new filter using a permanent pen.  Once the oil is all drained (see above) and any mess wiped up, use a strap wrench and some elbow grease to loosen the old  oil filter. You may also need a little prayer as these filters can sometimes be hard to remove. (I have more than once observed a junior bosun tightening an oil filter while trying to remove it). Once the filter is loosed you will be able to unwind it by hand, using your other hand to catch any oil spillage in a small receptacle. Place the old filter into the same receptacle for disposal. 

Smear new oil all around the seal of the new filter, wind it on by hand. It will often tell you on the side how much to tighten it, (read this before winding it into place). The oil filter only needs to be hand tight and not even fully hand tight. If you avoid tightening to far it will save the next engineer having to use that little prayer mentioned above.

Now we need to top up the engine oil. You will already know from the manual how much to have bought. When topping up oil, turn the bottle on its side to allow air into the bottle while your pouring, this will avoid gulping and spillage.

Top up about 90% of the expected amount and then give the oil 10 minutes to settle before checking the dip stick. Add the remainder slowly. Giving the oil a chance to pour through the whole engine before checking the level at the dip stick again. Be careful not to over fill.  Sometimes if the dip stick is reading over full, a 10 minute wait allows the oil to settles and the level will be better. If you do over fill use the extraction pump to lower the level again but always be patient.

The final step as always is to check you work, run the engine back up to temperature, close it down and check the dip stick a final time to be sure.

Your engine will now spend the winter in new oil and start the next season with the new oil.

GEARBOX OIL- DIESEL ENGINE DIESEL ENGINE WINTERISATION

Tools

• Impeller puller or 2 pairs of long nose pliers
• Screwdriver or socket to match the impeller bolts
• Blue roll (or strong kitchen roll)

I like to remove the impeller for the winter rather than leave the vanes locked in a crushed position. This can only be done after the other winterisation items as you can not run the engine again once the impeller is removed. If you are still afloat ensure the sea cock is closed. Remove the cover. loosening bolts opposite each other first.

Remove the impeller, ideally with an impeller remover or 2 pairs of long nose pliers, block up the holes with blue roll. An old crewmate of mine used to hang the impeller over the ignition key socket to ensure he did not re start the engine without the impeller fitted.  However I log these items so I have a list to work to next time, (see future de winterisation article).

AIR SYSTEM OF A DIESEL ENGINE – WINTERISATION

Tools

• 2 Oily rags
• Fogging Oil

Remove the air filter (and dispose of it) and squirt a little “fogging oil” in. Crank the engine but don’t start it (manually engage the stop solenoid while turning the engine over). This will help lubricate the cylinders. Replace the filter and stuff an oily rag into the air intake to block it. If the boat is ashore stuff another oily rag into the exhaust

BELTS- WINTERISATION

Tools

• Socket set/wrench

Loosen the alternator and relax the tension on the belts.

BATTERIES- WINTERISATION

Tools

• Socket set/wrenches
• Grease (use marine grease if near salt water or dielectric silicon grease if the boat is stored away from the sea or only used inland.)
• Smart charger (or trickle charger)
• Rags
• Gloves or barrier cream

Some of the above checks are completed in the water and require the engine to run (fresh water and oil change). Having run the engine up to temperate and then closed it down, it is good practice to isolate the battery so that no one can re start the engine while you are working on it.

If the boat is ashore, remove the batteries and store them at home or in a warm garage as part of your winterisation, ideally on a smart charger, which will recondition your battery. If the boat is afloat and the batteries are required for bilge pumps etc, then clean up the terminal and re grease them. Ideally hook up to shore power, (or solar or wind charging) as batteries will slowly discharge themselves when left alone.

FUEL TANK- WINTERISATION

Tools

• Fuel
• Additive

Never leave the tanks half full over the winter, they shoudl be either empty or fully pressed to reduce condensation. Consider adding a fuel additive or fuel bug preventer if the fuel is going to be sat over winter.

CLEANING

Tools

• Rags
• Fogging Spray
• Bilge cleaner

Wipe down everything, ensuring you remove any salt deposits from any surfaces. Clean the bilges (we will paint the bilges later as part of the winter maintenance programme). Give the whole engine a light spray of fogging spray.

LOG- DIESEL ENGINE WINTERISATION

Make sure you log (record) your full diesel engine winterisation (and therefore what needs undone before re launching). it would be painful to forget there is an oily rage in the exhaust, blue roll in the water intake or no impeller in the water pump! Finally take the opportunity to source perished hoses, belts and service parts for winter maintenance and next spring’s de winterisation.