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Old 17-06-2021, 17:55   #1
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Alternator belt tension

For a 3ym30 engine I need to know the proper tension for a 3/8" gates belt with an old balmar alt.

I read 1/32" x inches between pulleys with a 25 lb force. Is that correct?

I also need to know the proper tension for a J10 belt on the same engine, different alternator, delco remy 28SI.
I have the proper kricket measuring device, but do not know what yammer spec for 3ym30 serpentine belt tension is.

Thanks very much.
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Old 17-06-2021, 21:09   #2
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Re: Alternator belt tension

Quote:
Originally Posted by rgleason View Post
For a 3ym30 engine I need to know the proper tension for a 3/8" gates belt with an old balmar alt.

I read 1/32" x inches between pulleys with a 25 lb force. Is that correct?

I also need to know the proper tension for a J10 belt on the same engine, different alternator, delco remy 28SI.
I have the proper kricket measuring device, but do not know what yammer spec for 3ym30 serpentine belt tension is.

Thanks very much.
U have a belt tension gauge? Not 1/32, that’s impossible ( and potentially damaging to bearings.)without a tension screw. 1/3 “ deflection if retentioning used belt. Tad less defection w/ new belt 1/4” . Give it a good push between upper pulleys,

I use a smaller pry for leverage and it takes a good pull to get the belt that taunght.

Don’t know the serp belt tension spec, however, same theory applies, very snug, not so much you cant twist the belt at its longest run.
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Old 18-06-2021, 04:57   #3
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Re: Alternator belt tension

Sohum, thanks.
You wrote:
"... Not 1/32, that’s impossible ( and potentially damaging to bearings.)without a tension screw."

Agreed.

I wrote that I had found this suggestion.. " inches between sheaves x 1/32" with 25lb pressure " - Is that correct?

I don't have a v belt tensioner. It's at about 1/4" now but I think I will loosen it a little.

Still want to know more about serpentine belts. What is the experience out there?
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Old 18-06-2021, 06:23   #4
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Re: Alternator belt tension

Best tool to do this task: https://www.amazon.com/OTC-6673-Auto...00I198J0&psc=1
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Old 18-06-2021, 06:50   #5
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Re: Alternator belt tension

Here are the Dayco tension recommendations.


https://www.daycoproducts.com/stuff/...._4.18.13_.pdf


After a 3-5 minute run-in, Dayco recommends 112 pounds for a 3/8" v-belt. They do not list 10-rib belts in the table, but extrapolating would lead to a 300 pound tension.
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Old 18-06-2021, 07:10   #6
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Re: Alternator belt tension

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Originally Posted by Jammer View Post
Here are the Dayco tension recommendations.


https://www.daycoproducts.com/stuff/...._4.18.13_.pdf


After a 3-5 minute run-in, Dayco recommends 112 pounds for a 3/8" v-belt. They do not list 10-rib belts in the table, but extrapolating would lead to a 300 pound tension.


Good chart Jammer, I also like the specs about used belt because by experience the belt will break if you use the same tension as you would for a new belt.
I know that the OTC tension gauge is a pretty expensive tool but it could also be used for serpentine belt and timing belt.
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Old 18-06-2021, 07:14   #7
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Re: Alternator belt tension

To some degree, the goal is to get enough tension that the belt isn't slipping, but not much more than needed (too much is hard on bearings). Depending on how highly loaded the belt is, it's not necessarily all that sensitive a setting.
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Old 18-06-2021, 08:15   #8
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Re: Alternator belt tension

Thanks, that is all useful.
I once had it to tight & our mechanic caught this error.

So now I am cautious, too loose the alt pulley heats up and freezes bearing, too tight and engine and pump bearings wear out.

I suppose a temp gun would help with the first problem and a real belt gage with the second problem.
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Old 18-06-2021, 08:23   #9
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Re: Alternator belt tension

Kricket tools for v belts and multi/poly v

https://www.daycoproducts.com/dayco%...tension-gauges
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