Do I need a new alternator?

[AnviL Man]

What keeps shredding my alternator belt? Is the alternator bad? Or is the idler pulley bad? Could it be the flywheel? Both alternator and idler pulley will spin a couple revolutions with the spin of a hand. Should they spin longer than that? Can anyone recommend a good replacement alternator?

 

[Tim75]

Have you checked the condition of all the pulleys? As in rough or rusty surface on "V" surfaces. Maybe they could be polished? DON'T do it with the engine running! You could lose fingers!

Have you checked the alignment of all pulleys? As the idler pivots, does it wobble out of alignment?

 

[AnviL Man]

Have you checked the condition of all the pulleys? As in rough or rusty surface on "V" surfaces. Maybe they could be polished? DON'T do it with the engine running! You could lose fingers!

Have you checked the alignment of all pulleys? As the idler pivots, does it wobble out of alignment?

The idler pulley does not look bad, the plastic seems to be in good condition. The grooves the belt sits in are fine, the condition of the bearing itself does not seem bad, it'll spin a few times around with the whirl from my hand. The alternator pulley on the other hand is showing some signs of wear. Running my fingers on the grooves I can feel some roughness but nothing extreme. There is no visible rust but there is some slight white corrosion on it. I have not checked any alignment, to be honest I am not exactly sure how to. You say "as it pivots" by that do you mean when it's compressed in with a ratchet to take a belt on or off? I am not sure of the pulley wobbling or not, I don't think so. I've greased that fitting there as well, I'll check tomorrow if there is any wobbling for that piece.

 

[Tim75]

You are correct- the pivot of the idler to maintain belt tension.
Also, check for cracked/broken brackets that can cause alignment issues under belt tension. Loose or stripped bolts?

 

[AnviL Man]

I did a little more looking today. I installed a new belt, but prior to that I put a ratchet on the idler pulley and I compressed it in and out a few times, it seems sturdy. It doesn't wobble or feel loose at all. I took some fine grit sandpaper and went over the V grooves of the alternator pulley and then cleaned it up pretty good. I also checked to see if the alternator itself was loose which it was not. No loose bolts that I can see. I then installed the new belt and fired it up and let it run for a few minutes. I inspected it the best I could while it was running. It doesn't appear that anything is loose or out of alignment, I looked at it from both sides while it was running and it appears to my eye that the belt is traveling around normally. I am at a loss as to why it's eating up belts. I guess the real test would be out on the water.
https://www.youtube.com/watch?v=qxzvX5fzrGU[video=youtube;qxzvX5fzrGU]https://www.youtube.com/watch?v=qxzvX5fzrGU[/video]

 

[Lumps]

Is it possible something else is coming into contact with it? Like the underside of you engine bay cover? Or something like that

 

[AnviL Man]

Not that I am aware of.

 

[UKGlenn]

I had the same problem and replaced the alternator as it is the only item to put any load on the belt. The old ones pulley was slightly corroded but there is no way of testing the alternator bearings or resistance at the speed it spins. My thinking was that it was putting to much stress on the belt. New one has been fine for two years now. Also replaced the belt with a car one from an auto spares for about £10. Can't remember the part number but if you do a search for alternator belts on here then the thread should come up.

 

[AnviL Man]

Hey Glenn thanks. Would you happen to have the link to the correct alternator? On the parts page it lists three different alternators for my boat. Version 1,2 and 3. I am not sure which one I need. I am searching eBay for an equivalent because the ones on the parts page are almost $600.

 

[UKGlenn]

I took mine off and googled the manufacturer part numbers on it. It came back as a standard alternator made by one of the companies I don't remember which now but it cost about £120.