Is the air filter really necessary ?

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antares

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The air filter element on a VP 2003t is a sort of sponge which is housed in a plastic box housing,and it's not renewable in as much as you have to buy the whole thing which the local marine engineer tells me costs about 90 quid plus tax which is a lot of money for a filter. He says don't bother, it's a very low dust environment on a small sailing boat, right?, and he would just remove all the loose bits of the oily sponge remaining and replace the housing box, basically empty. Is this a sensible move or is it a false economy which is just encouraging some far worse problem down the line? Any experience of this, comments would be welcome. Many thanks
 
Air "filter" on the Kipper is a mushroom vent with some chicken wire, presumably to stop chickens getting in since anything smaller is getting sucked in. Always puzzled me, I thought there should be some sort of actual filter.
 
I would fit something to protect the engine. I would probably go down the aftermarket car air filter route many of which simply attach to the pipe with jubilee clips. Sods law:2.3.0 states quite clearly that the minute you run the engine with no induction protection is the very minute you drop a box of sawdust ect down the engine hatch.
 
Our Yanmar does not have an air filter.
The air box is empty but it draws the air in through a pipe pointing downwards.
This way it has to suck something up instead of something falling in.
 
The air filter is there to stop dirt getting into the cylinders. The cylinders suck in a lot of air, particularly at high revs.

There are a lot of engines out there that run with no filters. It doesn't mean that the engines are better off without, rather the reverse. Running without filters is rather like playing Russian roulette, with the downside of seriously reducing the life of your engine.

Even with a full engine box in a well sheltered part of the boat, my filters need cleaning every three months or so.
 
TradewindSailor said:
The air filter is there to stop dirt getting into the cylinders. The cylinders suck in a lot of air, particularly at high revs.

There are a lot of engines out there that run with no filters. It doesn't mean that the engines are better off without, rather the reverse. Running without filters is rather like playing Russian roulette, with the downside of seriously reducing the life of your engine.
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Good advice.

There's generally three ways to cause harm to your engine. Via the fuel, via the oil and via the air. That's what filters are designed for.
 
There's no standard air filter for the Thornycroft 235 in The Kipper - what after market filter would you recommend? It's a 3 litre normally aspirated low revving lump.
 
There's no air filter on the VP MD22. If it's good enough for the engine designers, it's good enough for me. The engine room on a yacht is a relatively dust free environment.
 
I forget the exact source, but I was once told by an engine builder of some repute that it had been found that doing away with air filters on the engines in one formula or another of racing car in the quest for minimum intake restriction gave a detectable increase in power. The problem was that the gain was short-lived. After a race or two, the filterless engines had a power output lower than the engines with filters. The culprit, dirt and dust deposits in the inlet tract and premature minor wear within the engine itself caused by the aspiration of abrasive particles.

Relatively dust free environment or not, I wouldn't run a boat engine without a filter.
 
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