Anyone know how long an alternator on a 93 XJ usually? Mine has 148K
miles on it, and there's no record that it was ever replaced. Would
having it rebuilt or replaced be a good idea, or should I just wait
until when/if it actually fails. I'm just a bit paranoid because the
alternator on my previous vehicle, a Dodge Colt, needed replacing not
once but twice.

Also I've noticed the voltage as read on the dashboard voltmeter
occasionally drops to 12 volts, but I assume this is OK since it still
runs fine and is above the red line on the meter.

Monte Castleman, <<Spamfilter in Use>>
Bloomington, MN to email, remove the "q" from my address

 

Monte Castleman wrote:
> Anyone know how long an alternator on a 93 XJ usually? Mine has 148K
> miles on it, and there's no record that it was ever replaced. Would
> having it rebuilt or replaced be a good idea, or should I just wait
> until when/if it actually fails. I'm just a bit paranoid because the
> alternator on my previous vehicle, a Dodge Colt, needed replacing not
> once but twice.

They run till they don't run no more. :]

I've seen alternators die after 4000 miles and others last over
200,000 miles. The material they use seems to last longer than the
old carbon brush ones.

> Also I've noticed the voltage as read on the dashboard voltmeter
> occasionally drops to 12 volts, but I assume this is OK since it still
> runs fine and is above the red line on the meter.

That's normal. Just the low end of the charging cycle. Only way to know
for sure is to put a tester on the charging system.