Air Intake Element

Steve Dion · May 12, 2014

Joe: Most of the time the foam just disappears. I assume that they get old and are ingested into the engine. I think is was more of a noise silencer. You may want to check the archives.

About the only thing in the engine compartment is the foam and belt dust which the foam probably cannot stop any how.

Nom De Guerre · May 12, 2014

I wouldn't run any engine without an air intake filter. Either the factory install or an aftermarket unit.

You risk engine damage if you choose to run without one. Yes, on most sailboats that risk is much lower, but it still exists.

Why take the chance?

splax · May 12, 2014

I have read where a K&N air filter was installed in place of the foam element. I would like to try that. I advise against running the engine without an air filter element.

wufibugs · May 12, 2014

I doubt that the open cell material used by Yanmar would be much of a silencer. For a while I used the foam used in some motorcycle filters. After realizing that the environment of the engine compartment is, by contrast to auto and cycle demands, pretty clean, I settled on making an inexpensive "cold air intake" [picture in the archives] system that has worked fine with no appreciable increase in noise.

centerline · May 12, 2014

while I agree there are more benefits to having an air filter installed than not, there have been in the past, and still are now, so many marine engines that have nothing more than a screen to keep the big stuff out of the intake.... and as for air restriction, the original air intake on my westerbeke 30 (4 cylinder) has an opening of 3/4"x 1.5inches... the engineers thought this would be enough of a hole to let all the air thru that the engine needs, so I dont see where any filter you could ever use would have any more restriction than that... unless it plugs up with belt dust

Don Lucas · May 12, 2014

there's a filter

post a link

Benny17441 · May 12, 2014

The shop manual indicates the air filter is there to remove airborne particles. It also indicates that the polyurethane filter element is reusable and should be cleaned with soap and water every 250 hours. At the time the foam should be inspected for holes or tears and the filter discarded if any are found. The foam should be allowed to dry and replaced over the mesh cone and reinstalled. This has to be a joke as this foam element disintegrates well before 250 hours or if you try to remove it to clean it. I have observed over many years and from many sailors that these Yanmar engines seem to ingest the foam filter particles as well as belt dust without flinching so the loud warnings about impending doom for eliminating the foam elements are without foundation. The filter cover as well as the wire mesh canister do prevent larger objects from getting ingested into the engines and those should be kept.

richk · May 12, 2014

concur with Benny...

Benny17441 said:
The shop manual indicates the air filter is there to remove airborne particles. It also indicates that the polyurethane filter element is reusable and should be cleaned with soap and water every 250 hours. At the time the foam should be inspected for holes or tears and the filter discarded if any are found. The foam should be allowed to dry and replaced over the mesh cone and reinstalled. This has to be a joke as this foam element disintegrates well before 250 hours or if you try to remove it to clean it. I have observed over many years and from many sailors that these Yanmar engines seem to ingest the foam filter particles as well as belt dust without flinching so the loud warnings about impending doom for eliminating the foam elements are without foundation. The filter cover as well as the wire mesh canister do prevent larger objects from getting ingested into the engines and those should be kept.

That was my experience with my 3GM30F on my 35.
Rich

wufibugs · May 13, 2014

Ditto. No sign of my filter element except for the inky color of the oil.

Don Lucas · May 13, 2014

I googled it for my engine and didn't get find any filter other than the screen

I've thought of this in the past but decided that when it came down to it, there isn't much dirt/dust blowing around inside my boat

ben solomon · May 13, 2014

I have recently read Nigel Calder's engine book, and he has me scared to death! He states that even the smallest particles in a diesel can really destroy the engine. My point is, that Nigel Calder definitely recommends an air filter. I am aware of the difference between what a book might say versus real world.

Ben

bananabender56 · May 14, 2014

1990 Perkins, now on 7,350 hrs and no filter - no problem

Terry in Naples · May 14, 2014

My filter or whatever that stuff was in the cylinder disintegrated a few years ago. I was going to put foam in there but

seadaddler · May 14, 2014

K&N

I put a AUTO K&N filter on my 3YM30 but way too much noise yes it was so much noise in the cockpit that I am sure my wife when down below would have
been very unhappy because I was not happy with the noise I was hearing at the helm.
Nick

Bill Roosa · May 14, 2014

neither my Catalina 30, Hunter 37.5 or my present hunter 40.5 had air filters. the box and screens where there but no element. I made a DIY filter and it promptly got eaten. Thought it was a fuel problem as the revs dropped about 50 RPMs as the filter was eaten. Then it stopped and upon trying to find the "fuel" problem i discovered that there was not filter element. used the same poly open cell stuff you find in lawnmowers. I'm thinking that no filter is better than having it eat one. i was thinking of using the plastic "wool" that is used in fish tank filters but given past outcomes am not brave enough to try it. Thoughts?

Dan Johnson · May 14, 2014

Joe...

After not being able to find a reasonable replacement once the original screening material disappeared, I made a filter to keep out large bugs and small rodents from household aluminum screen wire using the existing frame.

Layed out two layers by measuring the diameter and circumfrance of the big and small ends and cutting on these lines when transferred to the screen wire on a flat surface.

Works fine, if not very quiet.

Chief RA · May 14, 2014

Raced motorcycles until I was 50, so, know much about carburetor filters. Do not think anything more than a screen is needed for sailboard inboards. Outboards are another argument: I would say it depends on the nearby soil/winds and an individual decision to make his/her own decision.
Chief

Benny17441 · May 14, 2014

Chief RA said:
Raced motorcycles until I was 50, so, know much about carburetor filters. Do not think anything more than a screen is needed for sailboard inboards. Outboards are another argument: I would say it depends on the nearby soil/winds and an individual decision to make his/her own decision.
Chief

A carburetor has precision machined passages and parts that need to be kept clean but these diesels only have an air intake tube with no moving parts. Fuel is supplied via the injectors and the throttle is controlled by the governor. It is the intake valve size that controls the volume of air entering the cylinder. Diesel engines run very lean by gasoline engine standards and combustion does not consume all the air leaving a portion for delayed oxidation of any unburned fuel. This creates the soot that so characterizes these engines. Perhaps because of this the volume of intake air is not very critical for the good operation of the engine. As a result the engine is not as sensitive as a gasoline engine might be to be operated without a filter. Like I said before these engines chew right through foam filter particles and belt dust without flinching.