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Old 11-16-2013, 03:44 PM   #1
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Dead Alternator?

I bought my 98 Wrangler Sport a few months ago, and so far have replaced the exhaust manifold, brake pads, front rotors, steering damper, crankshaft position sensor, spark plugs, and I think that's about it. I just want to get this thing tip top for the winter, but at this rate, I'm not sure it will ever be reliable.

So this is the newest development: I'm driving and the battery voltage indicator flat lines accompanied by the "check gauges" light. I get home before turning off the car. Start it back up and it seems to be fine, only now the voltage is at 12v when before it was at 14v. A few days later, I drive it around and the voltage meter keeps going off and on. I get home park it, come back later and to investigate. I remove battery terminals, clean everything with baking soda, rehydrate the battery cells, and start her back up. Now it's not turning over so well. Eventually the car is dead. I jump it, and it has a strange time starting. I have to give it a little gas while holding the ignition, but now if the RPMs drop in neutral it will stall. I finally, get it started and get it to my mechanic to park for Monday without it stalling out. The mechanic is just around the corner luckily.

So to recap, the current symptoms are:
-unpredictable battery voltage indicator
-radio flickering and going crazy
-engine stalls without gas
-seems battery isn't charging either

So is this merely a bad alternator? The engine sounds sketchy when running, like the pitch of its sound goes up and down.

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Old 11-16-2013, 04:08 PM   #2
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Get a buddy to drive you with the battery to an autoparts store like autozone who can load test it. I'm more incline to think it's the battery vs. alternator. A good alternator will not charge a dead battery and starting voltage is mainly dependant on the battery (cranking amps).

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Old 11-16-2013, 04:56 PM   #3
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But would a dead battery cause the car to die once the engine actually starts?
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Old 11-16-2013, 05:45 PM   #4
Knows a couple things...

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Few modern vehicles & all modern Wranglers require battery power to the alternator for the engine to run. If you were to disconnect the battery after starting the engine (not a good idea for computer reasons), the engine would die shortly afterward as the magnetic field inside the alternator died from lack of battery-provided exciter voltage.

Before doing anything, due to how the Voltmeter is acting, I would physically remove both battery connections & wire brush them plus the battery posts until they are bright & shiny clean. Then reattach the battery connectors & tighten the nut that holds the connector to the battery post tightly enough so the connector cannot be moved with your hand.

If that doesn't help, take the battery out & have it "load tested" by someone who knows what they are doing... and that rarely includes an auto parts store salesman. Go to a battery shop, they know what they are doing.
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Old 11-16-2013, 07:21 PM   #5
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I recently did an engine swap in mine, fired it up and it ran fine, but the voltage gauge slowly dropped to the redline, and the check gauges light came on. Jumped it, and it started but I had to hold on the throttle, since it would die at idle. Parked it, the next morning I picked up a new alternator, threw it in, and a week later, still no issues. Runs perfectly. I'd say that's your problem.
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Old 11-16-2013, 08:04 PM   #6
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Quote:
Originally Posted by MGHDTi View Post
I recently did an engine swap in mine, fired it up and it ran fine, but the voltage gauge slowly dropped to the redline, and the check gauges light came on. Jumped it, and it started but I had to hold on the throttle, since it would die at idle. Parked it, the next morning I picked up a new alternator, threw it in, and a week later, still no issues. Runs perfectly. I'd say that's your problem.

Thanks! Sounds exactly like my problem.

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