When to get a new Alternator

[billdo]

Should I wait until the red light comes on, or should I be proactive. I just had a scare with the battery. I thought it was the alternator, then the starter, and finally figured out it was simply the battery, it was 6 six years old.

So now I am worried about the alternator. I have an 2003 3.0i. I just unlocked the dash menu to check voltage. I got 12.0v on the new battery, probably is higher than that. And I got 13.6v with the car running at 2,000 rpm. Shouldn't it be higher than that? Should I be ready for the alternator to fail?

PS, hope your starter never gives out. What a PITA it is to change that thing.

[Perrier]

Originally Posted by billdo

I got 12.0v on the new battery, probably is higher than that. And I got 13.6v with the car running at 2,000 rpm.

These are the normal readings. i.e. alternator is fine

[Joshdub]

I have had a couple alternator failures in my BMWs and never did the red light come on. It could be because I caught it early enough or because the red alt fault light isn't all that reliable. Test or have your alternator tested. At idle I get 13.8-14v.

[Ricky Bobby]

^^^This. Run OBC test 9 while its running to see your voltage, as long as it doesnt go below 13v while running you're fine. Mine stays at a solid 13.5v

[billdo]

Ricky, that it how I got the 13.6 it was about 13.4 at idle, using test 9.

[sedwilkins]

Originally Posted by Ricky Bobby

^^^This. Run OBC test 9 while its running to see your voltage, as long as it doesnt go below 13v while running you're fine. Mine stays at a solid 13.5v

This is what I did. When your generator goes out, you can just replace the regulator. its a 75$ part...

[Joshdub]

Originally Posted by sedwilkins

This is what I did. When your generator goes out, you can just replace the regulator. its a 75$ part...

While that it true, the voltage regulator isn't the only thing that can ware out/fail.

[billdo]

It makes sense that after a 100k, the bearings in the alternator ought to be going. In fact the last time I put it back in, it had a slight play in it. It is only $200 and is an easy job. I will probably do it when I finish my E39 project.