No need for it
Q Our Kubota engine, marinised by Nanni, appears to lack an air filter. It just has a sealed emply plastic case with a spout. Is that right? MAGGIE ALLEN, via email A TONY REPLIES: Marine engines are not designed to operate in dusty atmospheres so Nanni have decided a filter is not necessary (you have an ‘intake silencer’). Many Vetus engines (Mitsubishi-based) have a similar arrangement, while some Isuzu engines just have a plate with a number of small holes; many Listers and Perkins engines had a metal cover over the intake, and BMCs have a wire mesh ‘filter’ which, with the way they tend to be serviced will never trap dust. None of these have a reputation for an unreasonably short life.
Even with engines in/under the living accommodation, most of the stuff that clogged filters on our hire fleet was blanket fluff and pet hairs, both of which will just get burned in the engine.