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BELT DUST

Aug 11, 2011
648
O'day 30 MD
With the recent and latest cleaning efforts, I have found quite a bit of belt dust on the engine. I believe I have my pulleys lined up. The tension according to the manual is correct. All the pulleys match as in the width and depth of the groove. I ask the list, is there something I have missed. Your thoughts are always appreciated.
"Happy Holidays tom you all"
 
Oct 22, 2014
15,747
CAL 35 Cruiser moored EVERETT WA
Merry Christmas.
Belt dust can be caused by several suspects.
  • Too loose belt
  • Too tight belt
  • Poor quality belt
  • High draw by alternator
  • out of alignment
  • bearings in pulleys failing.
Are a start. If everything else is good.. try a better quality belt. Be sure it is the right size.
 
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Likes: Justin_NSA
Sep 20, 2014
1,273
Rob Legg RL24 Chain O'Lakes
Check if the belts are straight in the pulleys. Lay a straight edge accross the pulleys and make sure it hits the pulley on both sides. Also how deep do the belts sit in the pulleys? If they are too deep, the belt maybe too narrow.
 
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Likes: jssailem
Jan 19, 2010
931
Catalina 34 Casco Bay
Belt jumping is what happened when the load changes. Your alternator reacts to then need for more or less output. You can usually hear this happen. The load up puts a momentary strain on the belt and it will jump . This activity often finds the belt digging deeper into the pulley and shaving the belt shoulders ( dust)
 
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Jan 4, 2006
3,794
Hunter 310 West Vancouver, B.C.
DO NOT use belts from the engine manufacturer. Cheap junk at a premium price. Use good brand names plus all of the above. Also check the condition of the inside of the sheaves. If they rusty, use#600 and sand with the circumference.

Describe how you check for alignment and tension. Some of the methods I have seen listed here would blow you out of the water (and I know you're not in that group).

Maybe send a picture of the engine and make as well.
 
Aug 11, 2011
648
O'day 30 MD
Universal M20. Straight edge and spring caliper. Belt tension measured with up down movement allowing 1/2 either way using manual force. Using Auto Zone 15430 belt or Dayco Top Cog 11A1090.
Sheaves have been checked visually. No dull spots or rough areas. Belt rests on the grooves (visual observance).
With a removal and visual/ touch inspection, belt has no wear, torn or cracked areas.
So that's it in a nutshell.
All you you that have answered. Does nobody have belt dust on your inboard engines (Those with electric propulsion need not respond!!!!)
Thanks
 
Feb 6, 1998
11,436
Canadian Sailcraft 36T Casco Bay, ME
We’ll need more information about the alternator, brand & model, internal or external regulation and amperage load. Battery bank size and chemistry will also help.. With the typical belt-wrap on most marine engines, a 3/8” belt is not going to be entirely dust free unless you have a small alt.. The article below goes into a lot more depth..

Marine Alternator Installation Tips & Tricks
 
Sep 20, 2014
1,273
Rob Legg RL24 Chain O'Lakes
Just thinking outside the box, do you know for sure it is belt dust? Could it instead be a rubber seal that is going bad on the crank or the water pump?
 
Jan 4, 2006
3,794
Hunter 310 West Vancouver, B.C.
Universal M20. Straight edge and spring caliper. Belt tension measured with up down movement allowing 1/2 either way using manual force. Using Auto Zone 15430 belt or Dayco Top Cog 11A1090.
Sheaves have been checked visually. No dull spots or rough areas. Belt rests on the grooves (visual observance).
Crap ...................... same as mine and yet I don't have any dust to speak of. Has this dust problem just appeared or maybe a longer lasting problem ?

All I can see at this point is @Maine Sail 's electrical load recommendations. Additionally, I also have a 55A alt. (factory original) with Balmar ARS-5 external regulation. Belt loading at its easiest.
 
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Dec 5, 2015
107
Oday 272LE Louisville, KY
The belt dust decreased significantly when I switched from a Gates Premium belt to a Dayco top cog belt on my little M 12 engine with the original Motorola alternator.
 
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Likes: Mechone
Mar 20, 2016
483
Beneteau 351 WYC Whitby
You should always use a gripnotched belt especially when doing around a small pulley such as an alternator.
A notched belt has grooves or notches that run perpendicular to the belt's length, which reduces the bending resistance of the belt. Notched belts can use the same pulleys as cross-section standard V-belts. They run cooler, last longer, and are about 2% more efficient than standard V-belts.
Or better still is to convert to serpentine and no dust ,no slip and lasts almost for ever
 
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Likes: StanleyJ
Sep 23, 2009
1,450
O'Day 34-At Last Rock Hall, Md
I had some belt dust when starting up in the morning after anchoring overnight. It lessened a lot when i stopped putting the battery switch on both after starting. Now i keep the swtch on for just the starting battery till rev up in the channel then switch to just the house battery for rest of the day. Has worked for the last few seasons with almost no belt dust. I think alternator load may be a more common belt dust source than thought.
 
Sep 20, 2014
1,273
Rob Legg RL24 Chain O'Lakes
What is the amp rating of your alternator? The primary purpose of a serpentine belt is that it has less slip under load and can handle the high torque requirements for these high output alternators. I stumbled on this when I converted an old motorhome to a high output alternator and changed the pulley. Most of the time I did not see the high demand, so I never saw an issue.
Something I just thought of is to try is Powertwist. This was a belt designed for the woodworking industry to reduce vibration. As it turns out, it also results in less wasted power and less slip. They have a marine application, so here is a link:
 
Aug 11, 2011
648
O'day 30 MD
The belt dust has increased lately after I put a little more tension on the belt. The V shape became more narrow and I have accumulated more dust on the engine and in the engine bay. I have just replaced the belt as I have a six hour motoring trip coming up. I have spares just incase. Its obvious that the sides are wearing under the tension. I may back it off a fraction and see if that makes a difference. It sure should help with any bearing wear.
 
Jan 19, 2010
931
Catalina 34 Casco Bay
The belt is the weak point, but the pulleys can also experience wear. Friction heat works on both. It sounds like you may have a slight mis-alignment. A replaced alternator or water pump that have(had) a slight spacing difference will cause excessive belt wear. When you replace the belt, try using a framing square to determine alignment of the pulleys.. The pulleys need to be in sync with the main crank pulley.
 
Mar 6, 2008
674
Catalina 1999 C36 MKII #1787 Coyote Point Marina, CA.
I had similar dust and the belt would vibrate instead of running smoothly. The engine would also vibrate excessively. The alternator bracket broke eventually. After replacing the bracket there is no dust and no engine vibration. I suspect the bracket was cracked causing the alternator to swing and cause the belt dust and engine vibration.
Check your alternator bracket. My engine is M35B.
 
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Jul 5, 2011
584
Oday 28 Madison, CT
My Universal M12 throws dust. Am told they all do. Did not try belt brand change but have found that tensioning the belt did not help and the belt got slack again soon anyway, though the tensioning nut has not loosened. Net is I don't even adjust it anymore. It is a bit looser than spec bit it makes juice just fine and has never come off so I live with a yearly wipe up of a bit of dust and carry a spare belt for that rainy day.
 
Jan 4, 2006
3,794
Hunter 310 West Vancouver, B.C.
AGAIN- DO NOT ATTEMPT THIS TASK IN THE MANNER I DID. (It may not be safe!!! :yikes:;):D
Make sure you get your fingers waaaaaaaay down into the bottom of the groove on each pulley so you get every bit of corrosion off. I mean, what could go wrong :yikes::yikes::yikes: ?

Then maybe you could change your name to something like "Four Finger Pete" :biggrin:.