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WolfpackRider
06-18-2011, 11:00 PM
I have an '05 Mobius LSV. I'm having a problem breaking alternator belts. From what I understand, the things to look for are:

-rusted pulleys
-a bur on a pulley
-misaligned pulley

The pulleys are not rusty and I can't find any burs in them. As best as I can tell, they aren't misaligned, but I couldn't say that for sure. If one is misaligned, it can't be by too much.

I've been using Dayco 15425 belts. I have around 550 hours on the boat. I recently discovered a leaking hose near the top of the water circulation pump pulley that might be keeping the belt wet, but it doesn't seem like that should cause them to keep breaking this fast. The one I broke today couldn't have had more than 5 hours on it. The belts don't appear worn anywhere other than just being broken.

When installing the belt, I think I'm getting the right tension. It's fairly snug but still has around 1/2" to 3/4" deflection in the section between the alternator and the water circulation pulley.

Any ideas? I'm totally stumped. :confused:

DOCDRS
06-19-2011, 12:01 AM
I'm stumped to. Thought maybe too tight but deflection seems good. Water could def be cause biut not in 5 hours

Suprahunter
06-19-2011, 09:19 AM
I would try a Gates belt.

mmandley
06-20-2011, 11:12 AM
I would pull the alternator take it to the shop and have them check your bearing. If the alternator beering are going out it could be causing a huge amount of stress on the belt and breaking it.

Is there wear makrs on the belt at all? It is a clean break? Burn marks? DO you smell anything when you look in the engine bay after it breaks?

Even a misalgned pully will give you signs while the engine is running, you can visualy see the belt twisting if its missaligned.

If your cranking down on the belt like Super Man when doing the adjustment then you will not only wear the belt but the alternator bearings as well.

Do you ever hear and squeeling?

Other then this im at a loss for more ideas LOL

WolfpackRider
06-20-2011, 11:38 AM
I'm stumped to. Thought maybe too tight but deflection seems good. Water could def be cause biut not in 5 hours

Heh - sometimes it just nice to know I'm not the only one stumped. :)


I would try a Gates belt.

I'll give that a shot for my next belt.


I would pull the alternator take it to the shop and have them check your bearing. If the alternator bearing are going out it could be causing a huge amount of stress on the belt and breaking it.

Hmm, this sounds like it could fit the bill, especially if a bearing is getting really stiff for just a moment. The way it breaks is as if a pulley seizes for just a second and the drive pulley is strong enough to just snap the belt.


Is there wear marks on the belt at all? It is a clean break? Burn marks? DO you smell anything when you look in the engine bay after it breaks?

It's a pretty clean break. No wear or burn marks. I haven't noticed any funny smells.


Even a misaligned pulley will give you signs while the engine is running, you can visually see the belt twisting if its misaligned.

It doesn't look like it is twisting at all; so, I'm thinking the alignment is okay.


If your cranking down on the belt like Super Man when doing the adjustment then you will not only wear the belt but the alternator bearings as well.

Heh, Super Man isn't a phrase I'd use to describe me. :)

Do you ever hear and squealing?

Nope, no squealing.

Thanks for all the good questions/suggestions!

WolfpackRider
07-16-2011, 11:26 PM
I fixed the leaking hose and put on a Gates belt. I've put around 25 hours on the boat since then and haven't had any more problems breaking the belt. So, I'm thinking it was the fact that it was staying wet.

NCSUmoomba
07-25-2011, 11:36 PM
That is pretty interesting. I wouldn't have guessed that the water would have caused that. I was thinking a bearing wearing out. Sometimes, while the belt is off, you can spin the pulley and hear or feel it dragging or grabbing or wobbling.