TECH Changing engine oil filters on your boat in 10 steps

How to replace engine oil filters on board to avoid bad surprises? “Liveaboard” Fabio Portesan explains. Don’t be afraid to get your hands dirty!

Changing engine oil filters in 10 steps

Engine oil filters – Everything you need to know

You’ve probably had this experience before, perhaps just last summer: you’re finally on a boat and after having made a gourmet galley you’re ready to cast off your moorings. You turn the key in the control panel, but the engine after croaking a bit just doesn’t want to start. It will certainly be very difficult to retrieve a technician because they will all be on vacation, as you are.

Fortunately, after a close phone call to friends of friends you find a good soul willing to intervene but only after you have transferred half of your salary to him. In the boat, the mechanic checks everything and in five minutes figures out what the problem is-the verdict is “The fuel is dirty and has clogged the engine oil filters.”

Precisely for this reason and to avoid ruining your day, it will suffice to change the diesel fuel and oil filter regularly since so many sudden stops or failures of diesel engines are precisely due to the introduction of impure fuel or old, spent oil throughout the system. After the summer, with the boat at rest, it may be an opportune time to check the condition of the filter and replace it if necessary.

Engine oil filter change, what you need

It often happens that these routine engine service jobs are not performed by the owner because they are considered complicated. It really only takes very little expertise and time to do a great job. Protecting your engine by replacing a couple of filters is definitely one of those maintenance tasks that you can easily complete on your own. All you need to do first is to equip yourself with the replacement filters and some useful accessories and tools for the success of the procedure, which are:

• Oil Filter
• Oil absorbent pads to keep the bilge clean
• Latex gloves so you don’t get dirty
• Roll of paper that should never be missing in the boat
• Plastic bags
• Band Oil Wrench
• Screwdrivers if provided by your filters
• Small funnel
• Plastic bottles

Before moving on to the tutorial, I want to remind you that, albeit with minor variations different types of inboards will mount different types of engine oil filters. So like all boat work make sure you read your engine manual first under “Changing Oil and Diesel Filters” or similar.

The oil filter

Changing the oil filter is an integral part of the engine oil change operation. Changing oil often extends the life and health of your powertrain, and not by a small amount. This intervention is not only recommended but necessary every 50 engine hours.

If you use the powerplant for a short time and only a couple of times a month then you will need to change more frequently to prevent old oil, laden with contaminants, particulate matter and corrosive substances from acting negatively inside the engine. New oil will keep the powertrain clean and free of residue.

What to do, step by step to change engine oil filters

First, and if your engine has it, identify the oil suction pump. If you can’t find it, it will mean that you will have to get an external hand pump and a hose that you will then have to insert into the oil drain plug. You will find it more convenient to mount the pump to a bulkhead. The fortunate among us even have electric pumps intended for just this operation. Again, you will need to have your powerplant manual handy. Once the pump is in place, you will need to use absorbent pads to prevent oil from spreading “spotty” in the bilge. Unfortunately, changing is never a clean job, and in this regard you must also use a plastic bag as a base and place pads or paper towels on top of it.

Depending on factors such as the kilograms of liquid contained by the cup, collection space, location of the cap or pump, and accessibility to the workspace you will have to decide whether to use an open container such as a disposable pan or a bottle.

If you really do not have enough space, you will have to ingeniously use improvised containers such as two or three plastic bags used as a wineskin. If you opt for this solution, remember to tighten the bag at the opening with a zip tie otherwise there will be trouble.

In my case, I find that the bottles serve their function well and are convenient enough to be removed when full. In the worst case you will have to remove the oil from the dipstick and if the dipstick is threaded you will only have to screw the tube in otherwise even here you will have to think of alternative and creative solutions. The boat is also beautiful for this, often sharpening the wit and stimulating creativity. In any case, you will have to make sure that the hose is long enough to reach the bottom of the oil pan otherwise the remaining fluid will immediately contaminate the new fluid.

Engine oil filters, always when the engine is hot

And this fact brings us to the next point. Oil changes MUST be done when the engine is warm. Old oil tends to deposit all its impurities at the bottom of the sump. Cold oil in addition to being more difficult to extract will leave behind residue and dirt.

Instead, starting the engine and letting the oil warm up will achieve a higher degree of cleanliness by extracting the liquid in the next step. Once the oil is hot, turn off the engine. NEVER open caps with the engine running. That said and depending on the method d you choose, begin draining or pumping the spent oil until the liquid in the engine is completely depleted.

Once extracted take care to bring the bottles and containers full of waste oil to a disposal center or service station. Now it is time to change the oil filter.
Normally the oil cartridge should not be able to be unscrewed by hand, so you need the belt filter wrench we have available.

Curiously, 99 percent of the filters you can find on any boat are mounted upright and with the opening facing upward. This is done to give a way to unscrew the filter without spilling the contained liquid everywhere.
In the case of oil filters, it seems that most manufacturers have not calculated the force of gravity, and very often you will find the filter mounted in positions that will not only allow liquid to leak out but in some cases cause real oil spills worthy of a true natural disaster.

Therefore, be careful to unscrew the used filter by keeping it inside a plastic bag on pain of oil spilling into the bilge. Indeed, during this operation there are several opportunities to soil the boat if you are careless.

Belt the filter and wrench away.

Engine oil filters, don’t get dirty!

Try not to foul the bilge with oil or diesel fuel, and if it happens, clean it thoroughly before the automatic pumps come on. Spilling diesel fuel and oil into the sea in addition to being anti-ecological behavior can subject you to hefty fines. Sailor forewarned! Once the used filter is disassembled and disposed of properly equipped with the new filter.

Change the filter every time you change the oil. Before inserting it in place, distribute a drop of new oil on the gasket. Tighten by hand until the gasket makes contact with the backing and then give it one more turn.

This procedure is valid for cartridges on not-too-dated engines, but many boats still mount thrusters whose filters are locked by bar and bolt, and the procedure differs slightly. Remove the bolt, remove the underside of the housing, and change the filter. Clean and reinstall the new filter. If the filter has a gasket available replace it and grease it as described earlier. Close with its bolt.

The oil change

The last step in this procedure is the actual oil change! But what oil should I use? Mineral, synthetic, semi-synthetic, 5W-40, 10W-30?

And how many kilograms should I use? You certainly cannot decide for yourself what type of oil is recommended for your engine, so you will have to check this in the powertrain manual.
Locate the oil cap, get a funnel, and slowly pour in clean oil until the indicated amount is reached.

Be very careful not to put in too much or too little because either way the engine will suffer.
One final recommendation. Use the dipstick to check not only the level reached but also to see if the new oil has not been contaminated by the old oil. The liquid should be almost transparent. Good wind but most of all. good oil change!

Fabio S. Portesan