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Alternator Belt Dust Fix

Posted: Mon Sep 19, 2016 9:58 pm
by Vento Solare
I don't know how many people have issues with the alternator belt generating a bunch of black dust as I have experienced on Vento Solare. After doing some research, I decided to upgrade the V-belt and pulley system to a serpentine belt system. This provides more surface area for the belt and prevents slipping. The engine is a Yanmar 3YM30 with a Balmar 7 Series 110 amp alternator. The Serpentine Belt kit for this engine is 48-YSP-3YM-B with the 48-AM-102 alternator pulley substituted for the Balmar alternator (3YM30 stock alternator is Hitachi 65 or 80 amp). The kit comes with all parts required and a spare serpentine belt. Here is a Youtube installation video link.



Comparison of original alternator pulley with new one - note some of the black dust on the alternator (this was after vacuuming it)
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Water Pump Pulley Comparison
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Installation before belt guard is attached
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Installation with Belt Guard
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Re: Alternator Belt Dust Fix

Posted: Sun Sep 25, 2016 7:31 am
by Vento Solare
An update on the performance after installing the serpentine kit. The engine is noticeably smoother due to less vibration. Apparently the V-belt slipped enough and "chattered" causing the alternator to shake. With the serpentine belt there is absolutely no vibration at any engine rpm and I have not seen any belt dust accumulate as with the v-belt.

Re: Alternator Belt Dust Fix

Posted: Fri Mar 17, 2017 5:29 pm
by fxalbert
I had the same problem with the black dust. It's the alternator belt being eaten up and blowing dust EVERYWHERE. I discovered accidentally that if you have the blue wheel on the Alternator that's the reason. The blue belt wheel does line up with the Yanmar engine and you burn up belts (and blow black dust everywhere). I had the alternator rebuilt and the wheel changed and NO MORE DUST. I think the replacement wheel is white.

Frank Albert

Re: Alternator Belt Dust Fix

Posted: Mon Jul 24, 2017 11:30 am
by MK-Farthing
Preparing to upgrade to serpentine belt system/kit to solve the belt dust problem and have noticed on our boat that the raw water (RW) pump belt appears to also be generating belt dust - d/t poor alignment of the RW pulley. Has the RW pulley alignment been a problem for other boats or is there enough "forgiveness" in this part of the system that it is not a problem? Fixes/Suggestions?

Re: Alternator Belt Dust Fix

Posted: Tue May 14, 2019 10:07 pm
by Dan Corcoran
What are the benefits to make this worth $487? (for the kit).
Does anyone also buy the $72 belt buddy mentioned in the video?

Re: Alternator Belt Dust Fix

Posted: Wed May 15, 2019 2:06 am
by ctsailor55
Greetings all. As the prior owner of #261, I also saw a lot of belt dusting. What I found is that on #261, the boat came with the refrigeration option which included the 3rd battery and the larger (than Yanmar OEM alternator). The larger Balmar alternator came with a small pulley (I think it was blue color.) The tight radius is what causes the belt dusting. I spoke to Balmar and they gave me the info and said that a smaller pulley makes more power at a lower RPM. A larger diameter pulley requires more RPM for the same output. (As a side note, you should run the Yanmar hard on a regular basis.)
Suffice to say, they had a larger diameter pulley (that is more normal size for the alternator) that I bought and I think that cured the belt dusting issue. John G. now owns #261 and maybe he can shed light on the current status of his alternator. From my USCG marine inspection service, belt dusting is usually from tight radius or pulley misalignment friction.

Re: Alternator Belt Dust Fix

Posted: Wed May 15, 2019 6:26 am
by Vento Solare
The additional benefit I noticed after installing the Balmar serpentine belt kit is the engine ran smoother. This is because the load on the alternator was sufficient to cause the regular belt to slip and then catch again. Tightening the belt helped some, but did not eliminate the problem. I always thought it was just an attribute of the diesel engine. With the additional area provided to the belt on the upgrade there is absolutely zero slippage and the engine is much smoother at all RPMs.

Re: Alternator Belt Dust Fix

Posted: Mon Jun 03, 2019 7:30 pm
by Painkiller
Does installing this new belt system cause the tach pulse ratio to change?

Re: Alternator Belt Dust Fix

Posted: Mon Jun 03, 2019 8:06 pm
by Vento Solare
There is a slight difference. I used a hand held laser tach I bought on Amazon for $15 to recalibrate the boat tach. The calibration of the hand held was verified as accurate with an AC powered fan, measuring the blade rate.

Use this from another thread to calibrate the tach.

Re: Alternator Belt Dust Fix

Posted: Thu Jun 06, 2019 7:17 pm
by Painkiller
Right on! This is a must. While I've only run it less than hour so far, the engine does indeed run so much better (even quieter). I always thought it vibrated a lot – in retrospect, I’m surprised now it never jumped off its mounts. Thanks for the tip.