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Old 11-05-2017, 10:19 PM   #1
jocko
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2001 Z71/5.3 Alternator question

Ok gents - revised my original post after I found out some additional info about my truck.

My truck came with a 105 amp alternator (RPO K68).
I recently installed a new alternator at about 250k mi.
It was dang near impossible to install the belt, thought maybe my tensioner had bit the dust, just couldn't seem to stretch that belt on (and I know I shouldn't have to, have replaced the belt many times in 250k mi). But, I got it on.

Since then, the alternator works fine, BUT:
- noisier than usual
- HOT to the touch for hours after shutdown
- faint smell, even 3-4 months after install, "kinda" electrical, or "kinda" belt slipping rubber smell, "kinda" oil smell. Weird... And my wife can't smell it at all.

My working theory, in hindsight, is that perhaps the counter dude gave me a 130 amp alternator, which requires a slightly longer belt - that would explain my difficulty getting the correct belt for a 105 amp alternator on there (I mean I almost gave up, assumed SOMEthing was wrong, but then finally got it on, and it worked, so I left it). And the added pressure on the bearing is making the alternator "that" hot, and causing the increased noise.

While I have the paperwork that showed me the RPO for the original 105 amp alternator, unfortunately I don't have the paperwork from the alternator I bought a few months ago... idiot..

Anyway (here it is finally, my question) -

Is there any way to tell visually tell whether an alternator is a 105 or 130 amp alternator? Anyone have both belt pulley measurements handy? (or even just one, if you happen to know which alternator rating you have - or just the measurement, even if you don't know its rating - with two different measurements from folks, can deduce the smaller is the 105 amp) That's the only thing I could think of to confirm. Any other ideas greatly appreciated - including thoughts on the overall weird situation. I'm hesitant to rip it apart since everything is working fine. But I also feel like I'm kind of just biding my time until the new alternator fails at the most inopportune time - due to excessive bearing load, or perhaps I'll smoke my smallest gage alternator wire because it's transporting 130 amps now. I don't know.
Thanks for the help.

Last edited by jocko; 11-05-2017 at 10:27 PM.
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Old 11-07-2017, 08:33 AM   #2
homemade87
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Re: 2001 Z71/5.3 Alternator question

If you have not added any other accessories that need extra power then you are fine with your wiring . Al tho the alt is capable of 130 amps it will not produce it until it is called upon . The alt is not throwing 130amps at your truck . You truck is only using what it needs like before .

As long as the tensioner still has room to move on the spring the belt should be ok and nothing to worry about . AS for the heat the alt does get pretty hot to the touch . It is generating power and will get pretty hot . Under hood with the engine it will take some time to cool off . But does not affect the operation .

I would leave it alone and run it . It sounds just fine as long as the tensioner has room . Easy enough to tell . Put a 15mm on the bolt and see how much the tensioner moves .
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Old 11-07-2017, 10:36 AM   #3
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Re: 2001 Z71/5.3 Alternator question

Thanks homemade, appreciate the reply. Good point on demand vs output, thanks. Had to pry belt over final pulley when installing. But it does barely fit - I do understand what you mean in that ANY tensioner movement left would indicate I’m not stressing the bearing. I’m gonna recheck that when I get home. I think it will move a very little bit. That is the main reason I’m hoping to hear what someone a 105 or 130 amp pulley diameter is, just to compare. All good points - can live with the heat, it might be just fine, the noise is pretty noticeable though. But if it was gonna fail, it probably wouldn’t have lasted for this long.
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Old 11-07-2017, 12:25 PM   #4
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Re: 2001 Z71/5.3 Alternator question

checking my parts breakdown both alternators use the same pulley. The 105 amp is an ad230 series alternator with a stator diameter of 130mm. The 130 amp is an Ad244 series with 144mm stator diameter.
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Last edited by starterman99; 11-07-2017 at 01:13 PM.
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Old 11-07-2017, 04:19 PM   #5
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Re: 2001 Z71/5.3 Alternator question

Guess I’m stumped. Why does a 130 amp alternator-equipped truck require a longer drive belt?
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Old 11-07-2017, 05:19 PM   #6
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Re: 2001 Z71/5.3 Alternator question

Bigger outside diameter of alternator would move center of shaft higher from mounting point.
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Old 11-07-2017, 05:53 PM   #7
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Re: 2001 Z71/5.3 Alternator question

Ah. Ahhhhhh! Copy. Thanks. Well I think I still need to figure out whether I currently have a 105 or 130 amp installed at the moment. Any other visual way to tell - not sure I can accurately measure the stator dia with it in one piece. But a 14 mm diff might be sufficient to be able to tell the difference. Gotta look at it when I get a chance. Thanks again for the help, great info.
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Old 11-07-2017, 08:05 PM   #8
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Re: 2001 Z71/5.3 Alternator question

If the stator is completly enclosed in the aluminum housing it would be 105 amp.
the larger alternator would have an exposed stator between two aluminum housings.
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Old 11-09-2017, 11:47 PM   #9
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Re: 2001 Z71/5.3 Alternator question

Thank you!! Very much appreciate the answers.
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Old 11-10-2017, 08:41 PM   #10
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Re: 2001 Z71/5.3 Alternator question

I had a 130 amp on there. Swapped in a 105 (rather than change the belt - not much price difference!) and all is well. Tensioner, everything working just like they are supposed to. I think the wrong belt (shorter 105 amp alt) when installed on the 130 amp was putting too much stress on the bearing, this one isn't making a peep and there's the normal amount of belt slack. Thanks again - your description in post 8 made it easy to tell. Then I went to the parts store and looked at 2 side by side, then it was obvious. Screwed by the parts guy again!! Ha. Wish I'd realized I had a 105 amp to begin with. The 130 had some odd behavior too - pulsing much more pronounced than with the 105 (like when a turn signal is first selected, etc). Anyway, all good - thanks again.
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