K&N Filters on M25XP ?

[KWKloeber]

I believe before I went the route of buying a filter, I'd install the barbed elbow on the filter housing and measure the amount of vacuum.  If it's very low, I'd really question whether the crankcase breather would be effective pulling through a coalescing filter. 

I guess to be fair also measure any pressure on the crankcase breather hose.

-kk

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................................I'm also curious as to how much oil is collected in the oil/air separator.  I have read all the reviews & the main negative comment seems to be the low capacity of the unit I will use, so I am curious as to how much is created by that little 3 cylinder 21 HP boat engine.

Couple of different thoughts:

1.  I've read many stories of folks who have done this.  Most did not use filters and have had no issues.  A few did and reported that their filters lasted forever, at least in the few years they'd had 'em in.  I only recall one skipper noting his filter picked up anything measurable.

2.  That said, using my handy dandy Ron Hill "foam in a beer can" method for the past 18 years, I just didn't find all that much blow by through the breather.  Sure, there is more to clean up regularly, as I noted earlier I wished I'd done it before we left to come up here.  But it simply isn't that much, not enough to make me jump at doing it asap, and not enough for me to even consider bothering with a filter.

3.  Filter can't hurt, assuming it doesn't provide too much resistance to the oil breather output.  I just don't know technically.  Another reason I wouldn't bother.

I think Smitty did this on his C310, I'll see if I can find the link in his blog.