Dissolved Air Filter

RoyS

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Jun 3, 2012
1,739
Hunter 33 Steamboat Wharf, Hull, MA
Going to order one right now. Thanks for reminding me. Mine has four seasons of use or 400 hours and appears OK. Four years expected life works for me.
 
Feb 6, 1998
11,667
Canadian Sailcraft 36T Casco Bay, ME
Kevlar is actually a very weak fiber when separated from a woven mesh. Regardless, with that exception which typically is caused by uneven belt alignment and wear easily fixed, I’m surprised some claim filters get dirty.
"Easily fixed" is not really as easy as it may seem when a builder or owner installs an 80A to 100A + alternator on a 3/8" - 1/2" belt and then routinely deeply discharges a large house bank. Perfect alignment, even with perfectly clean pulleys, just can't solve an overloaded belt from dusting.. The ideal fix would be dual v-pulleys (still can have dusting issues due to non-perfectly matched belts) or a multi-rib belt system (virtually no belt dust at all) but most owners don't want to invest at this level so a $25.00 K&N or replacement foam prevents the engine from sucking in belt fibers...

These are not uncommon levels of belt dust at all...




To minimize belt dust...

1- Practice good battery management. Charging in bulk takes a toll on not only alternators but also on belts. The larger a bank gets in relation to the alternator the longer the alternator is in full-field/bulk mode demanding max belt load and running hot. Don't regularly discharge below 50% SOC and try to tailor your alternator choice to what your belt can handle. With external regulation you can de-rate the alternator using a Balmar regulator and Belt Load Manger until belt dusting is to a bare minimum.

2- Clean pulley grooves of rust at the beginning of each season. Rusty pulleys eat belts considerably faster.

3- When changing/upgrading alternators beware of the pivot bolt holes. We see lots and lots of *upgraded alternators running sloppy fitting pivot bolts. The pivot bolt should be properly sized for the holes. If the bolt is not sized properly it leads to misalignment issues and damage to the alternator foot/feet. *We also see many factory installations with sloppy pivot bolts.

4- On the adjustment arm tension bolt buy a longer bolt and back it up with a nut and lock washer. These tend to come loose over time in the soft aluminum alternator ears. Loose tension bolts, & "dished" washers clamping the adjuster arm, are perhaps one of the leading causes we see of belt dust/slipping..

5- If upgrading the alternator be aware that many larger aftermarket alternators ship with 1/2" pulleys and many small aux engines use 3/8" / 10mm belts. We see 1/2" pulleys in use with 3/8" belts quite frequently and the owner is often complaining of short belt life. Some 1/2" pulley's are machined deeper to accommodate a 3/8" belt but others are not..

6- Know what your belt can safely handle. We find 70-80A is about max for a 3/8" belt and 90-100A max for a 1/2" belt but this is with ideal pulley wrap and most engines do not have "ideal" pulley wrap. If you want to drive more than that you will need a multi-groove/serpentine type belt or a dual pulley set up. At 60-80A on a 3/8" belt there can still be some belt dust no matter how good the alignment. This is due to the lack of "belt wrap" on many small aux marine engines.

7- Pay attention to belt wrap around the crank and alternator pulley. The more wrap the more HP you can drive for a given belt size. If you have minimal wrap and a large bank consider a pulley upgrade.

8- Machined pulleys (billet steel) perform better with heat and driving large loads than do the stamped steel pulleys on many factory alternators.

9- With a new belt you'll need at least two adjustments. Let the belt "run in" then re-tension. Failing to re-tension the belt, after a run-in period, will also result in belt dust.

10- If you're not experienced at adjusting belts by feel, use a belt tension gauge..

11- Alignment, alignment, alignment... Perfect alignment can't solve it all but is critical to deriving the most HP from you belt system that you can with minimal belt dust.

There is more detail here: Marine Alternator Installation Tips & Tricks
 
Sep 26, 2008
546
Hunter 340 0 Wickford, RI
Don,
I've never found my 3GM30F Air Filter to be the least bit dirty, in 17 years.
Last year I had to replace my Mixing Elbow after complete loss of power and black soot on the water.
Not knowing it was the elbow at the time, I did think it was the air filter (really hoped) but it was as clean as each year before . I replaced it along with the elbow. Figured it served its purpose.
 

ToddS

.
Sep 11, 2017
248
Beneteau 373 Cape Cod
Update: Back around Memorial Day I put a new, stock, Yanmar foam filter on to replace my dissolved one... I considered everyone's input, but figured the previous owner maybe never changed it, and it only dissolved after a decade of neglect. I vowed to check more frequently. I used the boat from Memorial Day until Labor Day... mostly weekends with a couple week-long cruises in there. I'm going to ballpark the hours of engine use at around 30 hours or so... certainly less than 50 for sure. I just inspected that "new" air filter after 3 months, and the side facing the air intake had completely dissolved and been consumed... what a piece of junk! Who knows... maybe it's been dissolved since July. I'm going to look at swapping in a K&N filter... The stock one can't even outlast a single tank of diesel! Using these filters is WORSE than using no filter at all... the engine consumes the filter itself AND all of the contaminants that the filter was charged with catching. My only hesitation based on feedback here is that it will increase noise. (which will bother the admiral). I'm tempted to fabricate some type of canister/housing like the OEM filter intake housing, only slightly bigger to hold a K&N, and with some soundproofing on the outside of the housing, rather than asking one material to act as both the filter and the sound-dampening material. Hauling the boat this week, so this time of year extra projects don't take away from sailing time. Or maybe I'll get lazy and just clamp on a K&N and call it good enough... either way I'd strongly urge owners to check their filter/silencers.
 
Jul 7, 2004
8,402
Hunter 30T Cheney, KS
Good to know. When I bought Bella a few years back the filter was mostly gone. I wasn't sure what the story was there but i installed a new one. I better check it.
 
May 17, 2004
5,032
Beneteau Oceanis 37 Havre de Grace
Update: Back around Memorial Day I put a new, stock, Yanmar foam filter on to replace my dissolved one... I considered everyone's input, but figured the previous owner maybe never changed it, and it only dissolved after a decade of neglect. I vowed to check more frequently. I used the boat from Memorial Day until Labor Day... mostly weekends with a couple week-long cruises in there. I'm going to ballpark the hours of engine use at around 30 hours or so... certainly less than 50 for sure. I just inspected that "new" air filter after 3 months, and the side facing the air intake had completely dissolved and been consumed... what a piece of junk! Who knows... maybe it's been dissolved since July.
That’s a remarkable amount of deterioration. Our 3YM30 has 5 years and over 300 hours, and the filter is just a bit dirty, not yet deteriorating at all. I wonder if yours was exposed to some kind of chemical or vapor that could’ve sped the degradation.
 

ToddS

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Sep 11, 2017
248
Beneteau 373 Cape Cod
That’s a remarkable amount of deterioration. Our 3YM30 has 5 years and over 300 hours, and the filter is just a bit dirty, not yet deteriorating at all. I wonder if yours was exposed to some kind of chemical or vapor that could’ve sped the degradation.
Anything is possible... I've considered that, though I have noticed zero leaking oil, diesel, coolant, fluid of any sort over the same time period... conceivably it could be a vapor/gas, not a fluid, but no unusual smells that I've noticed. A very minor water leak in the engine bilge that I'm addressing, but that shouldn't contribute. I would estimate that the circle of missing foam where the air intake is, represents about 10-20% of the overall foam surface, but once that's missing, I have to believe the VAST majority of the incoming air goes through the hole, not through the remaining foam... path of least resistance. It is also possible that the replacement part itself sat on a shelf somewhere for a decade before Amazon shipped it to me, and it was ready to fall apart from the day I got it... that seems more likely. I have a blower fan in the engine compartment, and the INTAKE from that sits pretty close to (and pointing at) the filter... and the output from that sits over on the other side near the alternator. Likely just bad foam before I got it. Still, I can't imagine that even in its initial state that open-cell foam is catching too much fine particulate compared to a K&N, and the fact that I've seen two crumble, and the internet is filled with other folks with similar stories makes me want to upgrade. Heat could also contribute I suppose... though Massachusetts is hardly the hottest or most inhospitable places people are using Yanmar 3YM30s, and I haven't had any overheating issues (that I'm aware of)... no alarms ever... Haven't measured actual engine room temp, but no reason to think it is different than the "normal" hot sailboat engine room lots of us have. I'm not really trying to get to the bottom of the deterioration at this point (though conjecture is always welcome)... just thinking I'm going to try something better... can't think of downsides to a high-flow sturdier and washable filter if I can rig it up just right in the off-season. I'm no engineer or mechanic but from the looks of it, it seems like the OEM was made more to dampen sound than filter air if you ask me. If I motivate to make the change, I'll document it, and post before/after pics and results.
 
Jan 7, 2011
4,727
Oday 322 East Chicago, IN
I know when I first check my air filter on my 1988 O’Day 322 with a Yanmar 2GM20, there wasn’t much left of the air filter. I replaced it a few years ago. Happened to open the air filter housing today, and the filter stills looks good.

Greg
 
Jan 22, 2008
8,050
Beneteau 323 Annapolis MD
.... I'm no engineer or mechanic but from the looks of it, it seems like the OEM was made more to dampen sound than filter air if you ask me.
IIRC, but my manual is on the boat, it is not called an air cleaner- it is called a sliencer. But maybe that includes the housing? my 2 cents.
 
Mar 20, 2004
1,729
Hunter 356 and 216 Portland, ME
When Escape was new I asked about the air filter and was told by Hunter it's not a filter, it's a noise abatement for intake noise, never saw it dirty - but I wash it every year