Why You Should Inspect Your Foam Air Filter Element

kloudie1 · Mar 29, 2016

Don't know why Yanmar hasn't selected a material that does not degrade. I bought some good air filter foam and wrapped a little around the perf metal support.. works like a champ. The Yanmar ones are notorious for turning to plastic sand.

Justin_NSA · Mar 29, 2016

Mine wasn't quite as bad as Claude's but close when I bought her last year. It's on my annual maintenance schedule now until I get a feel for how long they last.

Benny17441 · Mar 29, 2016

I would not be surprised if half the Yanmars out there are running with just the metal mesh with the foam gone and digested by the engine.

Ralph Johnstone · Mar 29, 2016

Don't know what you guys are using for air where you are but I'd hate to be breathing that stuff

. I changed my media at eight years because it was eight years old ................ no deterioration, it was just ......... eight years old. I wash it out when it looks a little dirty, about every other year, and the second one still looks good to date. I think I'll hang on to this one a little longer.

Ron20324 · Mar 29, 2016

Dan, are you sure that's not a mouse?

Ken13559 · Mar 30, 2016

Benny17441 said:
I would not be surprised if half the Yanmars out there are running with just the metal mesh with the foam gone and digested by the engine.

Yup! Mine and friend's runs on metal.

. Really its not required. Just the metal silencer is good enough.

Gunni · Mar 30, 2016

Interesting. The 4JH3 doesn't have an air cleaner, just an air baffle. Keep the engine from ingesting wrenches I suppose.

Justin_NSA · Mar 30, 2016

I like that mud dobbers, spiders and other insects can't build nests in my engine :-O

Ilanortho · Mar 30, 2016

When I bought my Hunter 34 I took the air cleaner cover off and found all this crumbly crap surrounding the perforated screen; the foam had disintegrated and the engine swallowed it!!
Octane booster for a diesel?

Capt jgw · Mar 30, 2016

All engines really need an air filter. Dust is death, it scores the cylinder walls. Not much dust in the boat but there is some. The factory filter element for my Universal was a foam sleeve you could see through and cost $25. Can't see how it does any good at all, I found one for a lawnmower that fits for about $5. If it will stop the dust a lawnmower sees it will sure be good enough on the boat.

Gunni · Mar 30, 2016

Diesels pump a lot of air, and loaded diesels running at cruise have a lot of strain on them. I would not want to guess at the proper air cleaner size. And while I would only use a reinforced, oiled K&N cotton filter, I can find no flow specifications for them, or an application for my marine diesel.

pateco · Apr 1, 2016

Benny17441 said:
I would not be surprised if half the Yanmars out there are running with just the metal mesh with the foam gone and digested by the engine.

That's the one I have. No foam present upon inspection. Should I replace?

Ilanortho · Apr 2, 2016

Absolutely

Ilanortho · Apr 2, 2016

Dan_Y said:
Claude ---OMG! Ron... you might be on to something!
It's interesting the same filter on our h30 2GM20F looked new for the 7 years we sailed her.
I found this article in the h36 owner modes:
http://hunter.sailboatowners.com/mods.php?task=article&mid=71&aid=8126&mn=36
where the entire silencer was replaced with a K&N cotton filter, probably like Gunn referred to. Looks interesting.

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What mods to attach it? Do you have to oil it regularly? Thanks. Ilan

ITMaster · Apr 6, 2016

Like Gunni, I don't have a filter, nothing. There is the metal body for one but nothing in it. I'm original owner and there never was a filter in it. Yanmar 3JH3E 40 HP 3 Cyl. Diesel. It is enclosed inside an engine compartment with no outside flow from any source and sits below the water line.

wufibugs · Apr 6, 2016

After I bought Windmistress I changed the oil. At the end of the season, the oil was black as night. Decided to check the air filter and, as with many others, found nothing but metal. Reconfigured with motorcycle filter foam, but after giving it more thought and reading an earlier debate on the subject [most contend it's more of a silencer than a filter] I decided the engine compartment was a clean enough environment that I could get away with a "cold air intake" system. Pictures are posted on an earlier thread, but I got stainless flange and had it welded on a stainless tube for the intake. I used a small stainless washable cone air filter on the end.

Ilanortho · Apr 7, 2016

The granular crud my rags wipe off the engine every so often says it isn't so clean

wufibugs · Apr 7, 2016

The issue is what the filter element will keep out of the motor. I'm not sure how big the "granules" you refer to are so cannot say whether a foam filter or something coarser is necessary. My theory is that the most common "stuff" floating around the engine compartment comes from V belt deterioration, which may be faster or slower depending on the alignment and condition of the pulleys. Since the properly dimensioned belt for my Yanmar is available at any auto parts store, keeping a relatively fresh belt on the motor is a small expense and an easy job.