Strange Charging Problem

87 Laredo 4.0/AW4/242, Im driving home from work and the alternator gauge goes down to about 9-10. when i started it at work, it cranks over real slow, almost not starting. the alternator is less than a year old and has tghe lifetiome warrnty from Schucks. im coming up a hill on my way homre, and its under load at about 2500 rpm in 2nd gear, then the gauge jumps up to about 12 volts in the middle of the hill (not as if the higher rpm was driving th e gauge up). i get home and the gauge goes back down to about 9 volts. i try to start it back up and it cranks over barely and then nothing. to give you an ide3a, the AW4 was barely getting enough power to shift in city driving. What is going on with this thing?


PS: keep in miond that this rig never gets fourwheeled, so i cant see why normal driving would hamper the alternator if that is the culprit.

Take it in to have them test it.. Sounds like it is going bad

jk333 said:

PS: keep in miond that this rig never gets fourwheeled, so i cant see why normal driving would hamper the alternator if that is the culprit.

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Just because it hasn't been exposed to trail dirt and grime, :gee: doesn't mean it will never wear out. There's all sorts of regular plain ol road grime (trust me, I have a street bike and it gets dirty FAST!) out there to short unprotected connections, get into bearings, and so on and so forth.

Pull it, take it to import zone, they'll test it, then get a good USA rebuild/new unit. Or get one for a Durango (quality unit) and it'll have a higher output than the stock unit.:yelclap:

Good luck with the renix!

The problem with Schucks lifetime guarentee is you'll sick of returning their crappy parts. They will stand in back of the part but the quality is nfg.Buy your electrical & hard parts from a store that professional mechanics use. Most chain stores[Schucks, Auto Zone, Pep Boys, etc] use a lesser quality of remfg. and hard parts than places like Napa, Car Quest & other independent parts houses. That is how they keep prices down. Buy oil, filters, fluids & trinkets from the chain stores. Ask a professional where he buys his parts. Just my educated opinion. And it sure sounds like your alternator is bad.2X on having it tested.

Concur - observe the following caveats:

1) With big chain shops, they ovver a "Lifetime Warranty" because you are going to need it. Buying remans there is a crapshoot - they literally have them shipped over by the forty-foot CONEX box from China. Once upon a time, I wasted three and a half years holding down the counter at various Kragen's stores, and I've seen it. A good month saw a 40% return rate on starters and alternators (the company didn't track it, but I started to after a while. Return rates ran from a low of about 38% to a high of 89% or so, hovering right around 45%. Yep - from three in eight to nine in ten!)

2) Taking your alternator to have it tested at the store is inconclusive at best. Those benches are set to measure voltage output - at about a tenth of an Ampere (Hell, I've got flashlights that draw more than that!) It's not voltage output that gets you, it's current output. The alternator needs to maintain a minimum of 13.0VDC at full rated current output - and I'll guarandamntee you it's more than 0.1A DC! A dedicated shop will be able to tell you exactly what the max output of your alternator is at specified voltage (and do it regardless of your rated current output. That's how their benches work!) And, if you get them there, you're talking to the guy who actually does the building, the QC on the parts as they come in (if the shop is worth a damn) and the QC on the units as they go out (checking voltage and current output.) Why for do you think I deal with a small shop locally? You know - the one I talked into doing mail-order for us? Link in my sig, go to the "San Jose Generator" pages.

@ChevelleSS - the Durango unit won't swap into a RENIX-era without modding the brackets and installing an external regulator. Until 1990, AMC/Jeep used Delco alternators (Delco 12CS 1984-1986, Delco CS-130 1987-1990 - both internally regulated) and 1991-up got the ND units with the regulator in the PCM. You can get bigger Delcos without too much trouble, if your shop is up to scratch (up to 130-140A is fairly common and reasonable. Up to 200-225A if you want to fork over for it...)

I went through 3 brake master cylinders(Autozone) on my CJ in under a month(Lifetime Warranty my a**). 'Third one started leaking while I was bench-bleeding it. I gave up on all cheap re-mans after that. I've had real good luck with NAPA.