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Unread 03-31-2010, 10:59 PM   #1
Morgans_YJ_93
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1993 YJ Wrangler 
 
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Changing pulley wheels on Alternator?

So my alternator just went out in my 4.0 93 YJ. Its only pushing around 10 amps to the battery. I went out and got another one from a junk yard (this may not be what people recommend, but its what my budget allows for right now) that seems to be the exact same alternator, same manufacture, same bolt line up. But there is one difference, the pulley wheel on the new one is a bit bigger then the original one.

I tried removing the bolt that holds the wheel on but it is fairly stuck, even after applying some bolt buster. Also it is quite difficult because the wheel always wants to turn on you. Does anyone have any recommendations on how to remove this wheel?

Also is it necessary to remove the wheel. I figured that a smaller wheel would be better since it would turn more revolutions, but thats just what made sense in my head.

Thanks JF

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Unread 03-31-2010, 11:29 PM   #2
PlatinumNiner
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You have to use a puller to remove the pulley it's pressed on. How much bigger? If it's a hair you will be fine. If its a lot you may have charging problems at idle. Have you tried it yet? Are you sure the inside of the pulley isnt the same side and the lip on the outside isnt just a little taller? Worst case you bring them both to autozone. They will rent you a tool on the spot to remove both pulleys and swap them over. Do right there and return the puller. Its a free rental.
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Unread 03-31-2010, 11:38 PM   #3
Morgans_YJ_93
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The circumference of the original one is 6 inches, and the circumference of the second one is 7 inches.

That is about a fourth of an inch difference in the diameter of the wheel.

Will that second wheel be ok to install? Or do i need to replace the wheel.
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Unread 03-31-2010, 11:43 PM   #4
PlatinumNiner
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No way the pulley is that big on an alternator? They are tiny little pulleys. Doesnt make sense to me. As an example the pulley is normally small enough to fit the cap to a paint can over.
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Unread 04-01-2010, 12:35 AM   #5
MJMPC
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How about a pic of the alt and pulley? Like said some are pressed on but most have a nut to remove.
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Unread 04-01-2010, 12:46 AM   #6
Morgans_YJ_93
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This one had a nut to remove. No pics cuz i lost my phone in Australia

But i just put the newer one on deciding it would be better to have something on there rather then nothing for my commute tomorrow.

When I started it up, the battery immediately went from being pretty much no charge to having a little over normal. So i dont think this bigger wheel does any better or worse then the other. Im just gunna leave it and get rid of my old one.

Thanks for your help
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Unread 04-01-2010, 01:04 AM   #7
T-birdJunkie
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Circumference or Diameter is 7"?

If it's circumference, an inch shouldn't be so bad...if we're talking diameter...that's a HUUUUUUUGE difference.
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Unread 04-01-2010, 01:11 AM   #8
MJMPC
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The kind with the nut are best done with a impact wrench you can hold the pulley to stop it turnning.. If the pulley is bigger than stock all it will do is slow the alt down a bit wont hurt anything.
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Unread 04-01-2010, 04:06 AM   #9
Alfons
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The slight difference in pulley size won't make any difference. I've used both pulley sizes with the YJ alternators and have had no problems and no measurable difference in output.
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Unread 04-01-2010, 07:27 AM   #10
PlatinumNiner
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The nut holds the pulley in place however its still pressed on. You cant just remove the nut and have the pulley pop right off. 1" isnt crazy but i have never seen any alternator pulley that was 6 or 7 inches around. I looked up the replacement part for the 93 YJ 4.0 and the pulley is small maybr 4" around. Who knows either way glad it works. Just make sure it charges at idle.
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