M-18 air filter

[yelkenli]

I am looking for a solution to add an air filter to my M-18. My understanding is the round box is just a muffler.

I know this might be overkill. The engine is 40 years old and still working. But I have removed mud daubers from the engine compartment, so I don't consider the environment completely clean (an assumption for marine engines).

Has anyone added on an actual filter?

 

[Davidasailor26]

The intake breather in your photo can serve as both a silencer and coarse filter. Inside it originally was a metal mesh supporting a foam filter. Over the years the filter has probably broken down and been digested by the engine. The fact that the engine could eat that and still runs fine should give you some indication of the engine’s tolerance for debris. If you want something to keep out things like mud daubers just find a replacement element.

 

[Richard19068]

I use a K&N RE-0240. I bought a couple a few years ago and now am a bit shocked to see what they are currently selling for.

Amazon.com: K&N RE-0240 Universal Clamp-On Air Filter: Round Tapered; 1.5 in (38 mm) Flange ID; 3.5 in (89 mm) Height; 3 in (76 mm) Base; 3.5 in (89 mm) Top: Automotive

Buy K&N RE-0240 Universal Clamp-On Air Filter: Round Tapered; 1.5 in (38 mm) Flange ID; 3.5 in (89 mm) Height; 3 in (76 mm) Base; 3.5 in (89 mm) Top: Air Filters - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

I think this model might be discontinued now
Other sizes may work as long as the filter fits on the intake flange.

It is a bit louder than the "stock" setup though.

My 40 year old M-18 has a fair amount of blow-by so I knock out the insert on the top of the filter and put in a barb fitting to run a hose from the crankcase breather to the filter. Keeps the engine compartment quite a bit cleaner. That hose has an air oil separator to keep the oily crankase air a little cleaned up before going to the engine. Don't know if that is really necessary but it gives me a little extra piece of mind. As Davidsailor said these engines do have some tolerance for debris.