97XJMopar

Rig's a 97 XJ 4.0 5spd

Past couple of days my volt gauge would all of a sudden drop to nothing and my check gauges light would come on. I could get out and play with it crank it back up and it'd charge again.

Today it wouldnt charge all day so I removed it and took it to Advance Auto, they tested it as bad. I bought sum Electric Parts Cleaner hosed her down and she tested good.

Now thats its back in the Jeep its chargin so far but it's staying at like 13-14. When I first bought the Jeep it's stay on the high side of 14.

Is the alternator just getting worn or is there a few other things that may be wrong? I figured its prob just getting ready to go but then again it wants to charge, maybe cables or grounds?

xjbones

if it tested bad befor cleaning and good after....i'd say its gonna go out soon. brushes are prob worn.

XJSETH

i agree with bones its only a matter of time. i had a similar problem on my 98. just replace it. or run it till it dies again then replace it

5-90

Probably stuck brushes nearing EOL. The springs won't put as much force into keeping them in contact with the slip rings, so it would take less to stick them in the holder.

However, always always ALWAYS verify suspect voltage readings at the IP with a DMM of known calibration - the IP voltmeter is a notorious liar (especially in earlier models,) and should be used more for relative state-of-charge than for absolute quantified voltage readings...

97XJMopar

The only thing I dont understand is why Jeep would want to mount a Alternator on the lowest place possible on a off-road vehicle. Oh well off to Oreilly Auto payday thanks guys.

Has anyone ever been quoted on having a alternator rebuilt by a individual company or garage?

5-90

Just brushes you can do yourself with hand tools and a little patience. You just need to split the case halves, get into the back half of the case, and replace the brush holder assembly. Block the brushes back (usually using a toothpic - Delco brush kits come with one,) reassemble the halves, and pull the block. Spin it by hand to seat the brushes.

If the sliprings on the back of the armature are shiny or glazed, run some 240-400-grit Emery over them to break the shine/glaze and help seat the brushes.

On a Delco SI or CS series, this is something that I've been able to do in about fifteen minutes. Haven't had to do it on a Denso yet, but I'd imagine it's comparable.

Faling that, check with a local shop to get one done for you - you can probably find them in the Yellow section under Automotive. And, I talked the shop I use into doing mail-order a few years back, so you can get one from Rod as well (click the link in my sig, and scroll down. Click on the San Jose Generator link.)

97XJMopar

Luckily I contacted a local rebuild shop DB Electrical here in Kingsport, TN (800-753-2242). They quoted me $24 on brushes and labor. Thats well worth the money, I'd rather pay $24 than break into something I've never done before. Thanks for the quick help

5-90

Makes sense - I don't think of it anymore, since I can do Delcos with my eyes shut (and prefer to use Delco wherever possible anyhow - the power/volume/weight ratio is a good deal better than pretty much any other OEM, and you've got more options for handling the thing anyhow.)

Howler_GT

5-90...

You ever mount a Delco in an XJ?

I don't know if I could do that stuff with my eyes closed though, I might have to cheat and peek out of one of them

97XJMopar

Unfortunately I have a 97 XJ 4.0 with the NippenDenso

5-90

1984-1986XJ with gasoline engine - Delco 12SI
1987-1990XJ with gasoline engine - Delco CS130
1991-2001XJ with gasoline engine - that wretched Nippondenso.

Actually, ND's aren't really too bad (better than Mitsu, about on par with Bosch, and slightly liss good than Motorola. Better than Ford, about even with old Chrysler.)

The problem you'd run into with trying to mount a Delco CS130 or 12SI (easiest, since the bracketry can be had. The CS130 onto the 242ci in place of the ND is probably the easiest swap) is that the CS130 has an internal regulator and the ND has an external - inbuilt into the PCM.

Electrically, this isn't a great problem - simply mod the CS130 to be a "one-wire self-exciting" unit, and the regulator picks up its signal from inside the alternator case. No worries - I've installed those in damned near everything (the same trick can be done with an SI-series. I'm just not sure how it's done - it's always been done for me. I'm reasonably sure a regulator swap is involved.)

Where you'll have trouble is if the Air Police are involved - bypassing/not using the PCM regulator circuit will throw a persistent CEL/MIL code for a regulator fault (there's nothing wrong with it - it's just not being used) and it will cause you to fail smog checks - even though it doesn't have anything to do with smog or emissions control.

I've yet to find a way to bumfoozle the PCM into thinking the regulator circuit is being used, or to flash the PCM to ignore the regulator entirely.