# Yanmar 4JH air filter



## k1vsk (Jul 16, 2001)

First question:
I'm wondering if anyone with a 4JH has an air filter on their engine intake?
Some of the other Yanmars have filters but mine does not. Both the engine and service manuals indicate the location of the silencer where a filter would normally be. From these, it would appear that Yanmar didn't intend for a filter which doesn't make sense - I wouldn't expect lots of dust in the engine intake but it is possible for debris, belt dust, bugs, etc to enter.
Second question:
If I were to install a high capacity filter, would there be any long-term affect of restricting air flow to the engine.


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## RichH (Jul 10, 2000)

Most of what you see on marine diesels are not filters but 'silencers'. Even in the middle of the ocean, air is 'dirty' and containes a lot of hard submicronic particulate - especially if there is a desert or volcano upwind. Does this affect the service life of an engine ... probably not as these particles are extremely small and approach being 'harmless' to the engine as they contain little inertia / mass once inside. If you are keen to actually put a FILTER on the engine you can apply 'retro-fits' such as the dry paper elements from such manufacturers as "K&N", etc. ... just be sure to well 'oversize' the filter ... based on 'cubic ft. per miniute' of volumetric aspiration of the engine at 'wide open throttle'. Forget about 'wet' or oil-bath filters as they are essentially 'worthless'.


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## Giulietta (Nov 14, 2006)

K1

Just called ther Yanmar Importer over here and asked him the question.

I Have a 3JH4E, and they all must have an air filter.
It's a chicane type filter, and is a plastic box located on transmission side satarbord side.

He said its not urgent, but recommends you put one.

Can't post thwe photo, unfortunately. I have one if you PM me I can send it to you.


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## k1vsk (Jul 16, 2001)

Thanks guys.
I just checked the Yanmar service manual for the 1GM, 2GM and 3 GM/3HM engines and they too show only the silencer. It seems strange to me that only some (one?) Yanmar would have an air filter.
Regardless, I appreciate your responses and will check further on what kind of restriction the engine can tolerate.


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## billangiep (Dec 10, 2003)

For Yanmar silencer and silencer elements.... http://www.marinedieseldirect.com/catalogs/?owner=goodoldboat&show=ALL Parts catalogs for Yanmars and most other diesel engines. I just perchased two elements for my Yanmar 3GMD for around $14.00 each.
Bill,


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## Giulietta (Nov 14, 2006)

Are you talking about Silencers or Air filters??

I thought he lacks an air filter.


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## billangiep (Dec 10, 2003)

Giulietta,
The silencer has an air filter in it. Yanmar just calls them silencer elements.


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## k1vsk (Jul 16, 2001)

The silencer in both my 4JH and that of my son's 2GM20 is hollow - no filter! The silencer itself won't filter a baseball!


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## billangiep (Dec 10, 2003)

Yanmar makes a cone shaped air filter (silencer element) that fits inside the silencer. My past 2GM had the same filter silencer as my present 3GMD.
Bill,


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## billangiep (Dec 10, 2003)

Air filter (silencer) photo and part # 128170-12540[/B]Air Intake Silencer ElementAdd to Cart117.74


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## camaraderie (May 22, 2002)

I had a 4JH...there is no air filter and none is necessary. Their is a piece of what I would call "gauze" on the inner side orf the air intake which may need cleaning now and then from any oil "blow back" to preserve air flow.


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## TSOJOURNER (Dec 16, 1999)

*4jh air filter*

I have had a 4jh engine on two boats.
15,000 miles on one and 21,000 miles on the other all without a filter. my curent engine has a turbo also without a filter element.
it is not necessary according to Mack Boring, the east coast yanmar distributor.
faie winds,
eric


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## Giulietta (Nov 14, 2006)

Now I am getting confused. My engine has a silencer and it is separated from the air filter.

If only I could post the photo. I have a grey plastic *air filter*, on one side of the engine, in its rear, and on the other side the exhaust tube comes out of the cooling water heat exchanger, into a *separate silencer* that also prevents sea water from returning to the engine (syphon??).

My engine was made in 2006, could it be that they modified it??

However the Yanmar guy told me the air filter is needed. Maybe we get too much dust from North Africa!!

Apparentely over there you only get COLD AIR from Canada!!


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## RichH (Jul 10, 2000)

You sure do get dust from North Africa. Ever wonder why the snow in the Alps is sometimes .... sooooooo yellow? or the Italian sky is soooooo blue?


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## billangiep (Dec 10, 2003)

Giulietta,
Could the tube comming out of the heat exchanger going to the seperate silencer be a water lift muffler?
http://www.boatus-store.com/webapp/wcs/stores/servlet/product/20002/-1/20002/105468/20002/69/68/6


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## camaraderie (May 22, 2002)

Loooks like at least some of the new 4JH's have some sort of filter on them. 
http://www.mackboring.com/pdfs/JH.pdf
Maybe it is for the turbo models as I understand the turbo mechanisms are sensitive to dirt??? Giu...do you have a turbo or natural air model?


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## TSOJOURNER (Dec 16, 1999)

*4jh3hte*

Hi,
i have the 4jhshte 100+ hp turbo intercooled engine on kimberlite.
thete is just a metal screen on the silencer to keep out big particles.
there is no filter on this engine.
fair winds,
eric


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## TSOJOURNER (Dec 16, 1999)

*giueletta*

The grey plastic thing on the alternator and raw water pump side of the engine is a water lift muffler--probably made by vetus.
this is just a silencer for the exhaust and prevents a water siphon.
on the side of the engine with the oil filter is a can shaped device with a screen and a couple of latches on it. this is the "air cleaner" and has no filter inside and keeps big things from getting into your engine intake. i have used my 100hp turbo in africa and have had the red dust from the sahara all over the boat without any engine problems. the engine is a 2002 model and has 1800 hours on it.
fair winds,
]eric


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## k1vsk (Jul 16, 2001)

Kimberlite
I originally asked this question because someone on another board described some serious engine problems as a result of sucking in the remnants of a shreaded belt. 
My intent wasn't to debate the need for a filter. I was asking more to find out what, if any effect the filter could have on engine performance as there isn't any design spec from whcih I can homebrew my own flter to go in the silencer.
It makes sense dust sized particles would not cause any catastrophic damage, certainly in the short-term, but this guy had some belt fragments do a job on a couple of valve seats and springs requiring some head rework. I guess it could have been worse...

Any yes, I have talked to Yanmar folks - two tech types at different time and guess what? Got conflicting answers...


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## Giulietta (Nov 14, 2006)

Mine is a 3 cylinder normally aspirated and it is not the one on your picture.

Mine is a Saildrive model and the air filter is separated from the rest. Kimb could be right I did not look inside, but I believe it's a chcane type.

As soon as possible I get some photos and will come back here again.


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