Inablackout

OK guys,

My alternator recently died on my 02 A6 2.7t. It was pretty sudden. I left the house and the battery light was on, but after driving the gauge went back up to normal and the light went out. It was fine the rest of that day, the next day it repeated, then the next morning the light cane on and the volt gauge said just under 12 volts. Had battery and alternator tested and cane up with no charge coming from alt. What would have caused it to go just like that? It was fine, then all of a sudden just died.

I have read some of the other posts but didn't really see anything that addressed the issue as to why it would die that fast.

Thanks in advance

jcman

Worn brushes are the usual suspect on a high mile alternator.

Harleyguy

Sounds like one or more diodes went bad in the internal regulator. These can show up using an "old school" oscillascope analyzer. If you already had it tested and the alternator showed no output, then you need a new alternator. Diodes usually just go bad and quit working but can sometimes go on an intermittant basis until total failure occurs. They are also subject to heat sensitivity. They get hot and die and sometimes come back after cooling down.

the_duke

Every alternator I've ever had that died happened suddenly. Worked and then didn't.

rocketman4321

Mine also died suddenly. Was on a trip and the light came on while stuck in traffic. Noticed it would charge above 2000 rpm or so and sort of limped home on that.

Even better, the alternator's absolutely buried on this car. Requires the "service position" to get it out. That looks worse that it is--having now done it a couple times I can now get there in under an hour, and I'm a slow mechanic. You can use long bolts or threaded rod to stand in for the official VAG tool that supports the bumper.