I was driving my '91 L98 Coupe today, and I noticed my volts were slowly dropping on the idiot gauge... finally, the red battery symbol came on in that "information center" area... dash lights flickered, and the car finally died.

I'm assuming this is the alternator? This happened after I left my hood up for a few hours with the stupid hood lights on, which I couldn't believe would actually have drained my battery down... that and the red battery symbol on the dash makes me think it isn't the battery, it's the alternator... and the "leaving the hood up with underhood lights on" is just a coincidence.

Am I right in thinking this? If so, guess I'll have to go buy an alternator at Schuck's tomorrow. Also, is the alternator fairly easy to remove? I swapped out an alternator in my LS1 Camaro, and that was fairly easy.

 

The alternator is very easy to remove on an L98. Self explanitory when you take a look at the bolts holding it on. Just make sure you unplug the battery before removing it.

Before you go buy a new one:

Check wiring first. Check that battery cable bolted on the back of the alternator is on tight.

A quick test you can do is to hold the tip of screwdriver to the back center of the alternator where the roll bearing is. If the screwdriver sticks magnetically, the alternator is producing a charge.

Also, you can connect a voltmeter across the battery with the car off and observe the voltage reading. Then with the voltmeter in place, start the car. If the voltage does not immediately jump to 13-14 volts when the engine runs, the alternator is not charging the battery.

When my alternator went south, I opted to rebuild it myself using high quality internal parts as opposed to buying a remanufactured unit of questionable quality and reliability for a much higher price.

I bought the internal parts such as the voltage regulator and brush assembly at a local alternator rebuild shop.

You might only be needing a new brush assembly.

 

You may have a shorted battery??

 

Your alternator is not charging the battery and you need a replacement or your alternator rebuilt. An auto electric shop will do a better job and cost less than if you put a car parts rebuilt in. Recharge your battery with a battery charger for at least 12 hours (read the instructions on the charger), your battery was probably discharged due to the defective alternator and is the reason why the hood lights discharged your battery so quickly. Also, if your battery is of the age near its guarantee period, you may have a battery at the end of its life and it no longer has much amp-hour capacity and I recommend you replace it, winter is coming soon!

 

Well, changed the alternator out and got a new battery (needed one anyway). Car runs perfectly again...

Only problem I had was with the tensioner... it's in such a difficult spot! My '01 Camaro's tensioner was easier to get at... but still only held me up a few minutes. All in all, probably a half hour job.