I sucked a shop towel into my air intake - Westerbeke 13c - two

[Compass790]

Originally Posted by Lepke

Most marine engines that don't have air cleaners are assumed to be used on the water where there are few dust storms. If you add an air cleaner, be sure it allows the same air flow with the cleaner as it had without one. Otherwise the rest of its life the engine will be running in a rich condition meaning more soot in the oil. More soot in the oil means more engine wear.
To size an add on air cleaner find a tractor using a similar engine and it's probably bigger than the one you bought at the auto store.

Not looking for an argument as I agree with your good idea but pretty sure OP will be fine with an auto air filter as his engine is only 600cc or 37cu in American.
No dust storms at sea but plenty of rags, paper towels, fish scales, dust fibres belt dust etc etc. Tho probly not very damaging I prefer to keep that stuff outside of the engine. ymmv
Easy to check if air-filter causes restriction. Just try with & without air filter & see if revs change or governor arm/throttle linkage moves.
Mite be harder to determine on a CPU motor, I dont know about them

[RaymondR]

Originally Posted by Lepke

Most marine engines that don't have air cleaners are assumed to be used on the water where there are few dust storms. If you add an air cleaner, be sure it allows the same air flow with the cleaner as it had without one. Otherwise the rest of its life the engine will be running in a rich condition meaning more soot in the oil. More soot in the oil means more engine wear.
To size an add on air cleaner find a tractor using a similar engine and it's probably bigger than the one you bought at the auto store.

If it's sized to fit on a petrol auto engine it will most probably not starve a diesel of air. A 2L petrol engine running at 4,000 rpm is going to suck in a lot more air than a diesel which runs at 2,000 rpm.

[AKA-None]

Heck a piece of screen will do

[StoneCrab]

I'd keep an eye on your oil consumption.

If the paper fibers decided to stick to the cylinder walls, the rings could pick them up. Over time they will turn to carbon and possibly reduce compression or increase oil consumption.

If the compression rings get gummed up, your engine will be difficult to start. If it is the oil rings, your oil consumption will go up.

I agree with the previous posters about the desirability of adding a filter, but most diesels have a screen across the intake to stop gaskets and towels. It sounds like your engine doesn't have one.

On semi trucks, where the intake is pretty large, sucking towels and gaskets into the intake isn't uncommon. The intake airfilter, which looks like a shopvac filter is supplied with a new gaskets which are shipped inside the pleated cylinder. I've had mechanics throw the filter on without removing the gasket. The truck runs fine until the gasket makes its way down to the screen wher it starts cutting off airflow. This makes the engine put out black smoke like you just blew it up. It is an attention grabber the first time.... Inconvenient, but the fix is easy.... just remove the gasket from the screen. I never had one pass through the engine, though.

[jimbunyard]

Originally Posted by AKA-None

Heck a piece of screen will do

Yes, but I'd say nothing finer than 1/4" hardware cloth or similar. Anything finer has a possiblilty of getting sucked in if the screen gets caked with dirt or the intake gets partially blocked.