Went to get a new alternator today, but not sure which one I have. How can I tell and if I have the 65watt can I use the 100
??

 

i could be wrong but i'm pretty sure you can use either if they will fit in your XJ...

 

The guy at the counter said it depends on the plug? And I meant amps not watts...

 

Have the guy pull both for you and look at the plugs. If they're the same (they should be), get the 100 amp.

 

ah, thus the issue with parts stores...everybody has to order the damn thing...

 

whats the price difference?
i say if its only a few bucks (20 or less) i say order the 100.
if it comes in and isnt the right one take it back & exchange for the 65 and get a refund... then let us know

 

Stock XJ 91-01 is 90 so what part store do you go to. For my 99 I just used a 03 Dakota with the 3.9 it was 130 or 140 A little grinding to get it in but the plugs fit and it works wonders.

 

she's an 89, 4litre. so i don't know what other vehicle would provide a match. I'd like to go with a higher amp for future toys, So I think I am just going to get the 100 amper. if it doesn't fit, I need a new boat anchor anyway and the lesson will be worth it...I am done with it being in my garage and taking up precious MC room (aka $$$)...

 

Contact Jeep with your VIN number in this form. They'll tell all the factory options that came on your Jeep including alternator output rating.

http://www.jeep.com/wccsapp/universa...ull&category=U

It may take a week or so but they'll get back to you.

 

1) I'm going to have to assume (which I really don't like doing) that you're talking about the 1989 in your profile - it really helps to post what you're dealing with "in the clear" - in your question.

2) Alternators are rated in Amperes, not Watts. (Watts = Volts x Amps, in case you're wondering. Therefore, a 100A alternator would generate 1200 Watts, a 65A alternator would be good for 780 Watts.)

3) There are actually three options for the RENIX (1987-1990) 6-242 engine - 61A, 80A, and 100A. All may be used readily with the OEM mounting location and wiring - but if you are going to make effective full use of the 100A (by adding consistent electrical loads,) upgrading your wiring is recommended.

The 61A CS130 would be the "base" model alternator - found in vehicles with "power nothing" and basic trim packages (Base, Pioneer, probably Chief.)

The 80A would be the "mid-grade" alternator, found in Laredo trim, base vehicles with trailer tow, or the low-end Limited. Power windows & door locks is a potential giveaway here.

The 100A unit is the "high-end" unit - typically found in either the Limited with trailer tow, Laredo with all power options and trailer tow, or any trim level with heavy-duty alternator and trailer tow.

If you really want to know what you've got, you can find the OEM number on your current unit - if it's still there. It's probably an eight-digit number starting with a "1." This assumes, of course, that it's the original alternator - if it's been replaced before, that idea is right out the window! (Although, if there's a sticker with the standard Cham/Lester aftermarket number, that can be checked as well. It will be a four-digit number starting with "7" that will have a one- or two-digit suffix after a dash - the suffix indicates "clock position" of the connexions on the rear case half.)

The difference between the three output levels is internal, all three will swap freely.

 

thank you, thats about all I needed. My apologies on the clarity issue and in my haste putting watts over amps

 

No worries - I just figured it was something you hadn't learned yet, so I wanted to offer it up to you. Hope it helps!

 

Nope, I'm pretty savvy mechanically, but most of my time has been spent on motorcycles and big-boats...Its like breaking horses your whole life and then jumping on a Brahma for the first time...

 

As Well, in "OEM Tech" at the top of the page we have a JY Sticky that lists what other vehicles (can be found in the JY) that have parts that are bolt-on to almost bolt-on / slight modification needed for the Jeep XJ.
In there you can find, if you are really interested in upgrading for "future toys" as you put it, there is even beefier alt options, as well as other fun mods for future stuff.

For instance:
3. ZJ V8 alternator = more power to run accessories (some grinding required) 136A

5. 2.5L Dakota Alternator = bolt in, upgrades to 117A

Your talking 100A option for future stuff, why not just go a little bit more and get 117A. (Just dont forget to upgrade wiring even with a 100A) Can never really have overkill, lol

You can get these at the Pull it yourself parts yard for almost nothing and the ones I go to give anywhere from 30days - 1 year money back / exchange warranty on the parts you pull. Totally worth the money.

Why spend $80 on a stock alternator from autozone(or wherever) when you can get bigger for less w/a warranty.
Just another option / my thoughts...

 

Nnnnnghhh...

One more time - the ZJ and Dakota alternators will not work without wiring mods.

1984-1986 w/AMC or GM engine used the Delco 10SI or 12SI. (Internally regulated)
1987-1990 w/AMC engine used the Delco CS121 or CS130. (Internally regulated)
1991-2001 used the Nippondenso mid-sized alternator. (Externally regulated.)

The ND as used in the ZJ, WJ, WK, Dakota, Durango, and other later ChryCo products is similar to the 1991-up Jeep units - but won't cross straight over with the earlier Delcos.

Reports from the field indicate that there are donors for the Delco CS144 that will fit and give increased capacity. Also, any competent shop can upwind a Delco significantly (my buddy Rod can do a 140A unit for you for $140) and have it be nice and stable - known good and with warranty. The CS144 (some variants) are supposed to be a drop-in fit, direct wiring compatibility, and capacity up around 120-150A (IIRC.) I do not yet have a list of effective donors (although I've worked up a tentative list of donors for ND units for 1991-up rigs.)

Considering the OP has a RENIX rig, the ND will not be a drop-in fit, even if you modify the mounting! You'll have to install an external regulator for it to work properly - I usually suggest a Prestolite marine regulator, since they're very durable and a good value for the money. (Rod carries those as well, if you're so inclined and can't find one locally.)