Air filter - does size matter?

[bgary]

My air filter is looking a little ratty. I did my usual beginning-of-the-year cleaning (basically blew it out with some compressed air).

Last night I looked online to see what a replacement costs. And couldn’t find one like it (it’s a circular K&N clamp on). I can find smaller ones, taller ones, oval-shaped ones, but not a match.

Current thinking is is that size and shape probably don’t matter, as long as it fits and doesn’t restrict air flow. So I’m leaning toward getting a narrower-but-taller one which, at least mathematically, has more intake area than the old one.

But it thought I’d ask The Collected Wisdom: is there any downside to having a bigger air filter (i.e. one which -theoretically - would allow more air into the intake)?

Bruce

 

[Loren Beach]

Yes to more air

When I was "into cars" as a sort of hobby many decades ago, lowered resistance to the air flow going into an engine was always considered a "good thing".... :nerd:

 

[Christian Williams]

That K&N was recommended by Maine Sail and is the one on my current boat. Not that he's infallible.

I think it is intended to be oiled, maybe cleaned and oiled, periodically.

 

[sharonov]

I use K&N RU-2450 on my M25XP. Replaced original metal can filter that was missing actual filtering material in 2016. Did not notice any difference except feeling better about it.

 

[JSM]

Stumbled onto this thread some time back. Interesting take on using a Kubota tractor filter.

https://forums.sailboatowners.com/index.php?threads/how-i-made-my-m25xp-quiet.156298/

 

[Loren Beach]

Air Cleaner Caution

Not to get all dramatic on you, but if *anyone* has one of those Universal filter assemblies with the aluminum mesh inside, Remove that mesh. Immediately. :eek:

This applies to the M25XP and possibly the M25. Not sure if Universal used this on their other engines, and I know of owners who say their filter does not have this. (Or a prior owner removed it).

Universal XP25 - failure caused by airfilter

Hello all, Thought I would share a recent engine failure on my Olson 34 with an XP 25 engine. I had a recent engine stall that left me having to sail back to the marina in light conditions and adverse current. Here is the interesting failure mode: The engine stalled with a bit of weasing...

ericsonyachts.org

M25XP Air Intake woes

Today I discovered a problem with the air cleaner on my Universal M25XP, 1988 model. We have been trouble-shooting a problem with the engine stumbling and shuddering at about 1300 rpm. Since it's been a while since the valves were adjusted, that was done -- they were indeed out quite a ways...

ericsonyachts.org

While we will not know, sort of for sure, until the recipient of my old engine tears it down, my mechanic said that our crankcase blow-by problem for many years was likely caused by cylinder scoring from the pieces of that original mesh getting sucked in.

I would advise anyone with an 80's engine from this series to overhaul their air cleaner... or just replace it with a K&N.

 

[debonAir]

Interesting. I have my "air cleaner" off while I replace the timing gear cover. The air cleaner is nothing more than an egg-shaped metal box with a small mesh screen at the pointed end of the box. Anything smaller then about 1/16" diameter would get right into the engine I imagine? I think adapting any sort of air filter would be better than this thing? And this small mesh screen is nearly blocked with grease from the "breather" tube which Universal re-routed to under the air intake screen (the tractor shows it pointing down to grease the farm I guess). I suppose that's better than the bilge but now needs some cleaning.

For the people that have adapted an auto style cone filter.. what did you do with the breather tube?

 

[Christian Williams]

A cable tie directs the breather tube against/into the filter.

 

[bigd14]

I threaded a brass hose barbed elbow into the rubber portion of the K&N filter and ran the breather tube to that. I believe I got the idea from Maine Sail's website.

 

[Kenneth K]

K&N RU-2450 Universal Clamp-On Air Filter: Oval Straight $39.99
https://www.amazon.com/gp/product/B00062YQRA/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

That's about $12 more than the first one I bought a few years ago. Buy the K&N filter cleaner and you can clean and re-use.

Like Bigd14 said, you can drill and screw a hose barb into the flat underside and connect the breather tube directly to the filter.

 

[kiwisailor]

K&N RU-2450 Universal Clamp-On Air Filter: Oval Straight $39.99
https://www.amazon.com/gp/product/B00062YQRA/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

That's about $12 more than the first one I bought a few years ago. Buy the K&N filter cleaner and you can clean and re-use.

Like Bigd14 said, you can drill and screw a hose barb into the flat underside and connect the breather tube directly to the filter.

Will this size filter fit the Universal 5432?

 

[Kenneth K]

Will this size filter fit the Universal 5432?

You'd have to measure your intake tube size (and maybe top and side clearances) to know. Its a slip-on fit for an M25 in an E32-3.

 

[bgary]

Its a slip-on fit for an M25 in an E32-3.

Yes. Don't know about the M25XP, but the intake on my M25 is 1-3/4" in diameter, so any slip-on with a 1-3/4" ID flange will work.

I like the K&N stuff too.

Bruce

 

[Second Star]

I ran my breather hose down into a clear recycled plastic bottle zip tied onto one of the fwd engine mounts (M-18). This keeps the filter a bit cleaner and collects the very small amount of oil from the hose. Not sure if removing it from the air flow makes much difference to the engine … PCV is an emissions feature is it not?

 

[vanilladuck]

Just making the rounds on my Universal M25 after having the mixing elbow, water trap exhaust and alternator bracket changed out. Like most, the air filter contraption is bumbling around atop the engine with no real ability to filter air and more potential to imbue disaster into the intake manifold

Figured I would update and thank the contributors here. Thanks!

I'm ordering the K&N RU-2450 Ken lists above above (https://www.amazon.com/gp/product/B00062YQRA)

 

[Geoff W.]

I use K&N RU-2450 on my M25XP. Replaced original metal can filter that was missing actual filtering material in 2016. Did not notice any difference except feeling better about it.

I use this same filter on mine. It seems a little small, and I'd like to replace it with something slightly bigger, but I haven't noticed any ill effects.

 

[sharonov]

Do you guys clean and oil K&N filter? I suspect it needs oiling but I have never done it.

 

[Kenneth K]

I don't oil mine for 2 reasons. 1st is that the cloth media K&N uses looks like it's much finer of a mesh than the initial installation air cleaners on the universal engines. 2nd, the main contaminant seems to me to be belt dust, which it appears the paper media can trap. I think a mixture of oil and belt dust would be a greasy mess, and maybe cause more blockage to the filter.

K&N offers a filter cleaning fluid, which makes these filters reusable, I cleaned mine two year ago, and was shocked at how much black crud came out of it.

 

[Norwester]

Recently, members provided input to this very thread topic (air filter upgrade) but on a more general topic thread: "What maintenance TO-DOs without a sink."
I'll respond here to redirect onto specific topic thread:
Making this filter upgrade was a future project, but I thought it might required more depth of diesel functionality knowledge to address the issue. I guess I'm into it now.
Above @Kenneth K provides excellent illustration of K&N filter. Various members added methods of attaching a "crankcase hose," for which I had challenges finding, until returning another @Kenneth K post at this "Oil Dip Stick Leaking" thread to find he called it a "breather hose," which I found in my Universal/Westerbeke M25 parts manual (pic). "Ah Ha!"
A little A.I. generating support and highlighting, found this rationale for such a breather tube:
A marine diesel crankcase breather tube at the filter serves to vent excess pressure from the engine crankcase by allowing blow-by gases (a mixture of air and oil mist) to escape, while filtering out the oil droplets before releasing them back into the atmosphere or, in some systems, re-introducing them to the engine intake for re-combustion, thus preventing damage to seals, gaskets, and promoting cleaner emissions; essentially acting as a "relief valve" for the crankcase while maintaining proper lubrication within the engine.
Who knew! (one more diesel engine lesson learned today).
Members have shared various methods to collect oil/debris vented out of the breather elbo/tube before the vented air is "recycled" back through the owner's cut opening in the new K&N filter. Got it. Thanks!
Below is an added method found on Catalina34 site. Personally, I like the $10 In-Line Strainer option
Any lessons learned from folks having made the "upgrade" years ago? (cleaner bilge? increased ___ ?...)

 

[Kenneth K]

Members have shared various methods to collect oil/debris vented out of the breather elbo/tube before the vented air is "recycled" back through the owner's cut opening in the new K&N filter.

If the breather hose is installed as an inverted "U" (which is what most people do), I don't think any type of oil collection device is required. Oil vapors collect on the walls of the tube, so most of the "liquid" runoff flows back down the tube into the cylinder head. Some liquid oil may find its way to the air filter, which is fine for the engine, but might make a mess if there is too much oil.

But, if the breather hose dips downward (an upright "U"), then a collection device must be installed to prevent the oil from filling the bottom of the tube and blocking airflow.