Originally Posted By: dnewton3
Yes, I realize that there's no filter on this little engine. But the same can be said for hundreds of thousands of little air or liquid cooled engines with either splash or forced lubrication for four cycle engines. And there's obviously no practical way to filter wear metals from 2 cycle engines. And yet, they all just keep on running.
I expect Honda looked at this boat motor, and reviewed the wear patterns, wear rates, and "typical" seasonal use factor, and decided a filter just wasn't necessary for expected long life. I cannot think of any example that I'm aware of, either directly or indirectly, where a Honda engine stopped because of a perceived lack of filtration of it's lube system. Granted, there are plenty of engines that fail from too little or too much lube. But engines that are maintained according to the OEM specs? Nah - you just don't see those fail.
I looked at the Honda Marine website; the owner's manuals are available for viewing online. The older engines (with squarish motor hoods) don't use fitlers. The newer engines (with rounded motor hoods) do use filters. So presumably he has an older one. But I looked at one from each generation (of the four series listed) and observed the following:
they all have about 1.1 to 1.2 quarts oil capacity
they all have OCIs at 100 hours, regardless of filtration system being present or not
they all use 10w-30
So, it seems like the little engine from yesteryear is just about as capable as today's. Clearly Honda thought is was a good idea to add a filter; they would not have added cost and complexity for the joy of it without some ROI. But let's still look at this at face value. Adding the fitler didn't gain any appreciable OCI distance. Same sump capacity. Same oil grades. The OCI is 100 hours or every 6 months, regardless of generation of engine. I already asked the OP just what useage the motor was expected to endure? We have no indication that the 100 hours would even be usurped in a single season. Typically, those of us on BITOG have many engine-driven interests. Even if John-302 is retired and fishes daily, would he surpass the 100 hours in a season? He's probably like the rest of us, and goes fishing one week, drag racing another week, motorcycle riding another week, etc. While he's constantly in a motor driven conveyance, any one of them may not accumulate high usage for the season. Again, he could let us in on his dirty little secret, but he hasn't. So, I am left with assumptions from here on. Is this motor on a small fishing boat? Does it see frequent start/stop cycles? Is it pushing a sailboat out to sea, and only sees infrequent use? Is it used to ferry people to/from houseboats? Inquiring minds want to know!
I have three Honda pieces of equipment. A Goldwing (forced lube). Also a GX190 air cooled 4 cycle on my utility cart (cheap version of a 'Gator), and a little 4 cycle mini-rototiller. The latter two are splash lube'd. Clearly splash lube is inferior to forced lube, in general. And yet, these motor on with no signs of stopping. Just annual OCIs, with no filters.
I don't condem Mr. Beastly 302 for wanting to play and experiment. But he'll be "adding" lifecycle to the "little engine that already could".
He could gut the filter internally, and still take the life cycle out infinitely just because he's probably doubling the sump capacity. Add the bypass element media and he's heading "To infinity, and beyond" (credit Buzz Lightyear!).
And let's look at the cost involved. BMK set-up, plus annual filter costs, and extra oil costs. Compare that to no oil filter, and about 1 quart of the standard sump fill.
Just because he can do it, doesn't mean he should do it. There's just no "percievable" gain to it. My prediction is that he does it for the fun of it. And then a few seasons from now the BMK ends up on E-bay, or some other venture, because he'll realize the time/money/effort spent on this little outboard is wasted because it already will outlive his use for it.
Now, if he's trolling for clams for 8 hours a day, all summer long, and wants to extend his OCI for the sake of the OIL (rather than the motor), that's entirely different. It might actually make sense. But man, that's a lot of time in a little boat ...
I agree that there is no need for filtration on this engine. I have a model year 2000 BF9.9 and it is the exact same engine as the 15 with the exception of the carb bore size being slightly smaller for the 9.9.
So I have had my little 9.9 for nearly 10 years and I estimate that I use it 100 hours a year with annual OC's. It pushes my 14' aluminum jon boat with ease and is mostly used in salt water for area flats fishing. It has been very reliable with only a couple water impellers and a re-hub with a ss prop upgrade in that time.
Sorry about the messy garage
This engine still runs and looks like new and the oil does not change color at all on the dipstick.
So I can't understand what the OP thinks he will be gaining by adding this filtration to this engine and I believe he risks doing more damage than good.
As an aside, I have never seen an outboard engine with an air filter. Why is that?