Alternator Belt Dust Fix

[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)


Water Pump Pulley Comparison


Installation before belt guard is attached


Installation with Belt Guard

[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.

[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

[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?

[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?

[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.

[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.

[Painkiller]

Does installing this new belt system cause the tach pulse ratio to change?

[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.

[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.

[jerry]

Need some help troubleshooting. I bought my J/109 in 2005 and have one of the older ones (#44). It has the older Yanmar 3GM30FC engine, the larger 100 Amp Balmar Alternator as supplied when the boat was first purchased in 2003. I also have 3 105 AH AGM batteries that were upgraded and new about 4 years ago. I have a local marine engine shop do scheduled maintenance on the engine. I had occasional V-belt dust but nothing extreme. Last maintenance was November 2019 and old V-belt was replaced. Had about 25 hours of engine run time for delivery/return for the Round the County Race in the San Juans later same month. Then no further racing that winter and then nothing in 2020 due to COVID19 restrictions. Restarted sailing program this April. By my second race in April noticed "burnt rubber smell" and belt dust after only 20 minutes of driving to the race course. Inspected belt which appeared ok but a little loose (normal stretch for new belt?). Retightened belt which appeared to solve the issue. But then throughout the year I had to re-tighten belt at least twice (¾ to an inch more than my normal mark on the alternator arm) and still a fair amount of V-belt dust. Double checked with the marine engine shop and they had no explanation. Double checked alignment of the pulleys and appear ok. Two weeks ago we were going out for Wednesday buoy race and within 10 minutes engine alarm sounds and found belt shredded. Fortunately we were outside the breakwater, got the main sail up and the better news, I had bought a new V-belt about a month before (and it was on-board) and we were able to replace it in 20 minutes.

Marine engine shop doesn't have any easy answers as to why. So does anyone have an idea why after 15 years of use and never a V-belt issue I would have one blowout just a year after replacement and only around 50 hours max on new belt? The only issue I've come up with so far is they used an old belt and the rubber degraded. I'm a little hesitant to go on a long delivery or cruise for fear the belt will go again without knowing why. Should I upgrade to the serpentine belt system? Thanks for any insight.

[Vento Solare]

Jerry,

I would check a few things.

First would be to see if there was a bad batch of belts from the manufacturer. The problem may be due to that.
Check to see if any contaminants (water, oil, anti-freeze) might have gotten or are sprayed on the belt
Check to see if the belt tensioning is slipping causing it to come loose
Check the bearings on the alternator to see if they are going bad

You were smart to carry a spare as I always do and you should continue to do so!

[jerry]

Thanks for the quick reply:

"Bad batch" may be an issue but it was the official Yanmar belt, don't know if they code for manufacture date like they do on tires, but I will check with Engine Shop.

Haven't seen any water, antifreeze or oil, but I will double check

I was constantly checking if alternator was slipping but I marked a line on the adjustment arm and it never moved, so I assume as the belt got loose it was stretching.
[list4][/list]Will do some research but will check the bearings on the alternator

I bought the new belt because the "spare" I had was the original from the kit that came with the boat in 2003. I assumed the rubber on an 18 year old belt sitting in marine air for all those years probably would last long. It will become my back-up, back-up.

Thinks it's worth while to upgrade to the serpentine belts? I need one more winter project.

Thanks again

[Vento Solare]

I definitely recommend the serpentine belt upgrade as described in my post. Fixed the belt dust issue and the engine runs smoother.

It is a great winter project!

[35601]

I have a ton of dust but also have the Volvo engine. Anyone know of the kit for the volvo engine?