Alternator Belt Tension

Today I had a squeal come from the engine room above 1000 rpm but it seemed intermittent as throttling back a minute or two stopped it, I’m pretty sure it’s coming from the alternator (dual belt toothed v belt Balmar 200a). What’s the proper tension on these? Even though it’s a brand new JD 6068 it seems like there isn’t any sort of a tensioner, instead the alternator has a bolt you loosen and there is a track that bolt fits in that tensions it.

Also what’s the best way to confirm an alternator is working as the Balmar is not brand new but I was told it looked to be in perfect order.

Thanks!
Arthur

Measure the engine start batt voltage at the alt before starting.

Measure it again with the engine operating

12.6V or .7 or .8 off 13V to 14+ when operating.

If belt is squeaking, tighten it up a little. Subjective to say how tight is just right, belts are flexible and geometry can be whatever. But comfortable saying this: If it squeaks, it is too loose. Or something else is making the noise.

Yep, check batt volts with engine (and charger!) off. Normal charged batt is 12.6 or so, can be a little higher if you just turned the charger off.

Then start engine and rev to say 1000rpm. Check volts again. Should be 13.8-14.2, but the Balmar regulator may go a bit higher than 14.2 until it senses batts are topped off. See those volts and alt is fine.

There are belt tension gages available (Napa Auto parts for example has them) which takes some of the guess work out. You need a different one for a micro-V as the tensions are higher. Napa has both kinds - around $15 - 20 as I recall.

I find an adjusting tool w two concave V shaped ends and turn buckle type adjustment works well and worth a few bucks to keep in the spare parts bin. Loosening bolt and trying to adjust w a lever arm jammed in someplace just didn't work well for me. The tool holds everything in place while you tighten and check tension... EZ Peezey

Bacchus, do you have a link for the tool that you are talking about? This would make life so much easier if it fits my 6V92 DD. Thanks.

There is information and part numbers for belt tension tools in this article:

https://marinehowto.com/marine-alternator-installation-tips-tricks/








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This is the type... you might check Hbr Frt or local auto parts.
https://www.amazon.com/Supco-Belt-T...ocphy=9011777&hvtargid=pla-575152475703&psc=1

Agree with CMS...make your own....custom sized and padded for your engine setup.


Store bought break pretty easily.