Simon Westmacott devises a way to keep his bilges clean when changing the engine's oil filter

If your engine has an oil filter screwed on horizontally, such as the Volvo Penta MD2030 and many, many others, you’ve doubtless fumed at the arrangement whereby the contents of the oil filter canister – even after the sump has been drained – disappear into the engine bilge leaving a trail of oil down the side of your engine, writes Simon Westmacott.

Furthermore, said bilge is 95% inaccessible. After a lot of thinking, a BGO (blinding glimpse of the obvious) dawned and here is my solution.

First, check the filter will unscrew with the equipment you have. I like to use proper filter pliers. Unscrew the filter just enough to check it moves, but not so much that oil can escape.

With a nice sharp centre punch and at least a 20oz hammer, punch a small hole in the end of the canister, right at the top. You might need a few blows.

I did think about drilling the hole, but I didn’t want any swarf finding its way inside the filter canister in the boat. That said, I’m fairly sure it couldn’t get to the delivery side of the cartridge.

If you try punching the side of the canister, it will have too much spring to it unless you can chock it firmly – and there’s also the chance you may damage the threads on the central spigot.

Now use a strong rubber band to fix a piece of plastic sheet around the canister to form a gutter.

I cut a piece out of a large plastic dog food bag. Position something to catch the oil. Unscrew the canister half a turn until the punched hole is at the bottom.

As you go, carefully slide the gutter around the canister so it remains at the bottom.

Continues below…

Check the gutter is snugly up against the canister, under the rubber band and that the plastic stays in a gutter shape.

Punch another hole at what is now the top of the canister.

Use minimum force because the rubber seal against the block will be providing much less support, so more force is on the central spigot.

Once I had a dent, I angled the punch about 15° towards the middle of the canister so the force was more in that direction.

Once you’re through, oil will start to flow in quantity.

Chock the gutter so it will stay in position. I used the pliers and heavy duty cooking foil folded to keep it there.

The longer you can leave the rig in place, the more oil will end up in the tub.

I left the rig in place for a week simply for convenience, but the photo shows what had drained after about 15 minutes.

With any luck, there will be minimal oil spilled when the canister is finally unscrewed but, as with anything oily, have paper roll or rag handy.

There is very likely an advantage in doing this while the oil is cold (I did first drain the sump when it was hot) because -if it were hot, the gutter would most probably collapse.

Oil filter change: step by step

An oil filter in an engine

Credit: Simon Westmacott

1. Unscrew the filter just enough to check it moves.

a man unscrewing an oil filter cap from an engine

Credit: Simon Westmacott

2. Punch a small hole in the end of the filter at the top.

A piece of plastic being used to funnel oil from a boat engine into a container

Credit: Simon Westmacott

3. Use a rubber band to fix stiff plastic sheet.

Oil pouring from an engine on a boat

Credit: Simon Westmacott

4. The ‘catch’ after 15 minutes (at a cool 10ºC).

Oil filter on a boat engine

Credit: Simon Westmacott

5. New filter in place, not a drop of oil in sight.

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