5.9 Alternator Upgrade - JeepForum.com
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post #1 of 17 Old 12-03-2008, 04:17 PM Thread Starter
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5.9 Alternator Upgrade

***Solved! See posts below!****

Anyone that has done this swap for the 136A Alt answer me this.

98 Grand Cherokee 5.9 Alt
The Alt is obviously bigger, but from what I understood it would bolt right up. The bottom mount point doesn't seem to want to line up.
Did any of you have to grind the alternator bracket to ensure a proper fit?


Last edited by Razor.; 12-04-2008 at 05:09 AM.
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post #2 of 17 Old 12-03-2008, 06:41 PM Thread Starter
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Alright, I found I will have a bunch of grinding to do.
I will try and do a write up of the install
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post #3 of 17 Old 12-03-2008, 06:42 PM
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What year do you have? I know it fits in my 98 TJ and it fit in my 93 ZJ.

2004 Jeep Wrangler Rubicon
2003 Dodge Ram 3500

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post #4 of 17 Old 12-03-2008, 06:44 PM Thread Starter
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98 XJ. I pulled the bracket out and mocked it up on the table. I have to grind the corners and middle just a bit. More to come
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post #5 of 17 Old 12-03-2008, 10:46 PM
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Yup. I remember this. Lots 'o grinding. I did it on the Jeep.

I have 96. I was able to remove the battery, the skid plate, alt. harness, and some general B.S. out of the way and stick my head up in there (I have a lift to use) and grind off what I need with a dremel and a "4 angle grinder.

WATCH OUT FOR THE LOWER A/C line! It gets tight slipping it in and out of there, you dont want to knick/crimp it by accident. the 136A alt is a little bigger, and it WILL hang up here. loosen the bracket and zip tie it up away from the unibody. Ditto if you have automatic, I think.

Most of the grinding was towards the top and a little on the inner side of the bracket, IIRC. No matter, that's a beefy bracket. Wont tear that up even if you OVER grind it. I like my stuff to fit tight and factory like, so I kept the grinding to minimum.

Remember to change the pulley.
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post #6 of 17 Old 12-04-2008, 03:26 AM Thread Starter
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Ok, here are the pictures from the grind job. Didn't take me more then a couple of hours, and then a chilly torture test up the mountain. And from my above post you can see I installed it without grinding. That picture is why it won't fit with your factory bracket. Don't do what I did
First I got my Alternator from AutoZone. I gave them Part # 13387 (1998 Jeep Grand Cherokee, 5.9 V8), I paid $159 and some change with a $90 core exchange. I went in with the Alternator in hand. Be sure you get the black boot off of your old alternator, you will need it for the new one.
Then I went out to the Jeep ('98 XJ 4.0L), grabbed a cold one, and began the install.
  • First remove the serpentine belt using a 15mm socket and wrench to loosen the tensioner and idler puller.
  • Then I removed the Battery and battery tray using a 1/2" Wrench to remove the terminals and tie downs
. The tray has 3 nuts located just under the battery. I used a 15mm Socket w/ Long Extension.
  • I removed the alternator electrical connections with a 7mm socket and a 10mm socket
  • I separated the alternator and front alternator plate from the bracket using a 15mm socket for the lower mount bolt, a 15mm Socket and 15mm wrench through new battery access hole to get the top long bolt out, and a 15mm socket to remove the 3 nuts, 1 bolt holding the front plate.
  • The bracket is held onto the block with 2 studs (there are three you must remove, but only two holding the bracket on) and two bolts located on the back side. A 16mm Deep socket will get the three front studs out from the bottom, and a 15mm socket will get the two back bolts out from the top access hole. The bracket will separate from the block now.
  • After you are done removing it should look like this!
  • !!!!Be sure you get the black boot off of your old alternator, you will need it for the new one!!!
  • Ok, now you will grind! I mocked up the bracket and New Alternator on the table to see where exactly I needed to grind, I did this to avoid removing more material then necessary, this big boy needs all the support he can get.
  • As you can see from the above picture, the alternator doesn't exactly fit into the bracket, so you must remove some material in the corners and valley of the alternator bracket. I marked it like so.....
  • Note the boot direction on the alternators. They are different (and keyed), so I just swapped the boots from the old alt to the new alt using one 10mm deep socket.
  • Also the new alternator will have one extra groove on the pulley, just place the serpentine belt in the grooves furthest back leaving one in front of the belt unused. You can swap the pulleys if you so choose.

Last edited by Razor.; 12-04-2008 at 05:12 AM.
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post #7 of 17 Old 12-04-2008, 03:45 AM Thread Starter
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Ok, let us press on!

***Please wear Safety Glasses and ear protection*** I would hate anyone getting hurt over not taking simple precautions
  • After you have gotten all close and personal with your favorite material mover (Grinder on bracket action), it should look something like this. I removed a little, put it together, removed more, put it together, and repeated until the alt fit into its home. It ended up being quite a tight squeeze, but you can remove more if you don't want it that tight. Your choice
  • Now we will install the assembly onto the Jeep! Hooray!
  • First I raised the alternator through the bottom and hung it on the A/C bracket with zip ties, Watch your head! Don't trust the ties too much.
  • I then reinstalled the bracket using the 2 back 15mm bolts, and the front three studs (16mm deep socket)
  • I lowered the alternator into the bracket and installed the front plate, 3 15mm nuts, one short 15mm bolt, top long bolt and nut (15mm and 15mm wrench), and lower alternator bolt 15mm socket.
  • After you have done that, attach the electrical leads with the 3 10mm nuts, and 2 7mm nuts.
  • Reroute the serpentine belt (on the back grooves of the new alternator leaving one groove hanging out in the breeze) and tighten to what seems like tighter then it should be (I have done it so many times I just have a feel for how tight it should be ). Tighten by turning the 15mm tensioner bolt until tight, then secure by tightening the 15mm idler puller.
  • Reinstall the battery tray with 3 15mm nuts. And then the battery with 1/2" wrench on the terminals and the battery tie down bar.
And you should be done! Double check all your work, and then start her up! You will love the difference! Hope this helps everyone
You will note I didn't change the pulley, the pulley on the new alternator has one more groove then the factory one. The diameter is also a little bigger. It was negligible and I just left it on.
Attached Thumbnails
Top Alt Mounted Up.jpg  

Last edited by Razor.; 12-04-2008 at 05:15 AM.
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post #8 of 17 Old 12-04-2008, 04:44 AM Thread Starter
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Excuse me for not referencing my source of help. Refer to it as well. It will fill in just about anything I might have missed. Thanks for your help as well 4.0H.O.XJ!
"Firetoad", Tod. "Jeep Alternator Upgrade."BC4x4.com 3 Dec 2008 <http://www.bc4x4.com/tech/2004/jeepalt/>.
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post #9 of 17 Old 01-13-2011, 10:04 AM
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This is fantastic.

Originally Posted by Motorcharge View Post
So do you actually hear your thoughts in your head or is it just sort of a dull roar before you smash your face into your keyboard and just submit whatever dumb **** ended up on the page?
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post #10 of 17 Old 01-13-2011, 08:59 PM
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Yea i just recently saw this aswell, id like to add this mod to my list of crap i would like to do to the jeep later on.

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post #11 of 17 Old 01-13-2011, 11:47 PM
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Did the same thing with my jeep a couple months ago. Worked great. Just make sure you are really careful and take your time if you using an angle grinder like me. I had a couple of close calls lol

1993 Jeep Cherokee
Rubicon Express 4.5" Lift
33" Wrangler Duratracs
30/44 4.88s Disks all around
Rear Detroit/Open front
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post #12 of 17 Old 07-09-2011, 09:23 AM
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glad i was linked to this...im in the process of doing this to my XJ right now.
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post #13 of 17 Old 08-02-2011, 12:41 PM
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just finished doing this with a 120 amp alt. I didn't trim it enough (i had done the same as yours, but it still didn't fit). It was even rubbing with the front mount.
I had some spare brake caliper bolts. I just put one in place of the lower bolt with a nut at the end. It works perfectly. Its a 13mm instead of a 15mm. It should hold if it can hold a brake caliper..
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post #14 of 17 Old 11-13-2011, 07:07 PM
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Quick question. Would it hurt anything if I did this mod on a stock 96 XJ? I don't have any Aux lights or anything... Just want to be on the safe side for if/when I do add stuff...
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post #15 of 17 Old 01-14-2012, 12:41 AM
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