Alternator belts

[Tigerr]

My boat eats belts. I reckon I got less than 100 hours on the last belt - tension OK for a while, then some slippage and then a blown belt. (Beta 43 - main culprit being the coolant/12v alternator belt). Gates toothed belts - good quality.

At the beginning of the year I had a jam on the alternator pulley (obstructed by bolt) and a belt ran over the stuck pulley, and broke (lots of smoke!). On reflection - it must have created a bit of uneven pulley wear doing that but I didn't think that would be a big deal, Would a worn area on the alternator pulley-wheel lead to accelerated belt wear and loosening followed by belt failure? Is there a way to spot a worn out pulley wheel?

[Paringa]

No expert on this but i think you are answering your own question...

 

Did the belts break before regularly or after the jam? It is unlikely a manufacturing fault if it has happened regularly. I suspect the jam has caused some mis-alignment and this is causing the wear, 100 hours is not good enough for belt life.

 

Is the alternator pulley alligned? Is it wobbling? Is the whole alternator in-line, it might have been pulled out of true? Are there any rough bits of metal on the pulley?

 

Others will have suggestions to check. Good luck.

Edited September 11, 2013 by Paringa

[bigste]

A dicky pulley will chew the belt quite quickly if it is under a good load. I've had lots of dealings with belts. If it chewed belts before I'd be thinking about pulley sizes if everything else is right. Other than that have you installed a new powerful alternator which the old pullies can't handle.

[Paul C]

I guess its possible you introduced some misalignment when you fixed the jammed alternator pulley?

 

A too-loose belt will snap after only 100 hours or so. I'd be tempted to try again but check the alternator belt tension very regularly (like, every time the engine is started and run say 3-8 hours) for the first 100 hours or so, since belts initially 'stretch' then lead a long life at their slightly stretched from initially fitted position. Also, replace it with a decent belt, not a cheap substandard one.

[Tigerr]

Thanks for the replies. Will have a close look at the pulley V surface and se if there is a flat spot. It woudlnt really be an issue except that to change the belt I have to take off all 3 belts, dismantle a spacer bar assembly and then refit the lot - it is an hours work. Not huge fun on a sweltering day in a hot engine hole!

[Captain Fizz]

"Tension OK and then some slippage"

If you are allowing it to slip for any significant time it will break.

Sounds like it is an alignment problem or a burr or rough spot on a pulley.

[DHutch]

If its a thin/pressed pulley it could have bent it and opened out or changed the v-groove. As said, either that or you have introduced some alignment issue on fixing the bolt issue maybe. Certainly if it was fine before, something has happened.

 

If it was always poor, the pulley/belt isnt suitable, or your using the wrong belt for the pulley.

 

 

Daniel