BC4x4.COM four wheel drive, 4x4, offroad and fourwheeling site.

(You want amps? I got your amps!)

PRELUDE

OK, for some time now, I was wanting to add an electric fan to my beast. I was really wanting to install one of the 91-95 3.8L Taurus dual-speed fans that is all the rage these days. The only problem with this was the 33A continuous draw and 100+A startup draw. So, that meant that the stock 90A alternator would be working its tail off. The only other option that I had, besides the out-of-the-question USD$300+ hi-amp alternator upgrade, was to purchase a decent aftermarket fan that drew only around 10A or so continuous. The problem with this is that these fans are not cheap. So, I went on a mission to find a replacement hi-amp OEM alternator. I read about people looking at 120 amp models and one mention of a 136 amp model but nobody, as far as I know, ever confirmed that any of these would even work on paper. Guess what, for a mere USD$30, I was able to upgrade to a 136 amp alternator with very, very little effort! You say this can't be true. Well folks, it is and I am about to show you!

WHAT YOU HAVE

Here's a photo of my original alternator.

Ok, now, I know that the OEM 90 amp alternator(OEM PN:56005685AB) in my 97 TJ was also used in the following:

1997-1998 Dodge Dakota
1991-1998 Jeep Cherokee
1991-1992 Jeep Comanche
1992-1998 Jeep Grand Cherokee
1991-1998 Jeep Wrangler

Note: I have only confirmed this entire modification on a 1997 4.0L Jeep Wrangler. I am unsure as to what motor combinations the above vehicles came with in conjunction with this particular 90A alternator. This is an "ON YOUR OWN AND YOUR OWN RISK" type of modification. If your wiring is not up to the task, etc., you could burn your jeep to the ground or injure yourself. YOU HAVE BEEN WARNED!!

WHAT YOU NEED

Here's what you're looking for.

You are looking for an OEM 136 amp alternator(OEM PN:56027913) that was an option on the following vehicles(I am unsure of what motor combinations, etc. were required):

1997-1998 Dodge B.Series Van
1997-1998 Dodge Dakota
1998 Dodge Durango
1997-1998 Dodge Ram Pickup
1997-1998 Jeep Grand Cherokee

I got mine from a local Jeep yard for USD$30 out of a very clean 98 5.2L Limited that only had 60,000 miles on it when it was wrecked.

Here are the two alts. side by side. The higher amp. alternator is on the left.

I did quite a bit of research and found that the basic mounting dimensions and connections were the same between the two. You can see the physical size difference of the two. As a matter of fact the 136A alternator was 1 kg heavier. The only major difference was the direction of the plastic boot on the back of the alternator and the pulley is a 7 groove vs. my TJ's 6 groove. It was found that there was a 1 mm difference between the pulley diameters, but this is negligible and does not need to be addressed.

WHAT YOU NEED TO DO TO INSTALL

Ok, this mod is not much harder than installing a new alternator. I won't go into the details of changing the alternator, but rather, I will point out the details that must addressed during installation.

The first major difference between the two is the direction of the plastic boot. For ease of installation and clearance, this needs to be changed. By swapping the boots from the Wrangler to the Cherokee alternator, this change is easily accomplished. The boots are keyed (see red arrows) and install over the indicated stud below and locate on the small hole in the case (see green arrow).

The Wrangler boot is on the left and directs the exit of the boot away from the engine.

Details of the plastic boot positioning.

The other very minute detail to be attended to was the "spacer bushing" on the rear ear of the top alternator mount. The Cherokee's alternator's bushing (probably from rolling around on the floor) had been pushed too far inward and needed to be pressed back out. I accomplished this via a vise and large socket. Don't worry about pressing the bushing too far out because the mounting bolt will draw the bushing back tight again. The picture below shows the bushing after I pressed it out of the way:

The spacer bushing.

Finally, I mentioned that the Cherokee's pulley was a 7 groove pulley. If you wanted the extra work, you could simply swap the two alternators' pulleys. However, you do not need to do this. If you bias the belt to the rearward most six grooves, the belt and alternator will align and run just fine. You can see the alternator installed in the pic below with the belt biased towards the back.

Installed and ready to go. Notice how that the front groove on the pulley is unused.

Well, after the install, I tested the bad boy out. Everything seems to work just fine and I can crank the old stereo and run every electronic device in my jeep and hook up the Taurus fan to the battery and nothing even "blinks." Anyway, hopefully, someone will find this article helpful and save a few dollars in the process.

- Tod "Firetoad"

Except where otherwise noted, all contents on this site are Copyright 1999 - 2009 © 599244 BC Ltd. All rights reserved. No content on this site may be reproduced without express permission from 599244 BC Ltd.
Disclaimer: Activities and vehicle modifications appearing or described on this website and its pages may be potentially dangerous. We do not endorse any such activity for others or recommend it to any particular person - we simply describe our experiences and opinions. If you choose to engage in these activities, it is by your own free will and at your own volition. Use common sense and remember that none of this material is presented as being recommended by a professional mechanic or driving instructor. This information is presented for your amusement only. Do not take unwise risks, consult a certified professional if you are not sure of something. - 599244 BC Ltd. (bc4x4.com) and the authors of these articles assume no liability for how any particular individual chooses to use the information presented here.