alternator woes..

[vwtdi04]

I have 00 VW golf Tdi, two years ago my battery light was on, and found the voltage regulator faulty, replaced with used one, working fine until yesterday, on the highway going for two day holiday battery light came on, today came back, and found my voltage regulator to be faulty, one of the brushes was loose no longer attached by wire and spring, so I have replaced with new voltage regulator unit, and charged the battery, everything works fine until I hit highway speed, the battery light turns on and beeps, once I drop the speed under 120km/h ~ 75 mph light turns off.. I haven't replaced the alternator yet it is original 90amp. Is this indication of bad pulley,
there are no whining noises from alternator pulley or any odd sounds.

 

[Vince Waldon]

If you're on your second set of brushes there's a good chance the commutator is worn.... how did it look when you changed the brushes this time?

 

[BrianCT]

If you're on your second set of brushes there's a good chance the commutator is worn.... how did it look when you changed the brushes this time?

Second that. It also could be a stator/regulateur.

 

[Ski in NC]

If two sets of brushes got damaged, I bet that commutator (slip ring) is worn, especially out of round. So brushes hop as it spins. And it spins fast!! Something like 3X engine rpm. If that's the case, probably best to get a whole new alt.

My pulley failed, but first symptom was noise at idle where it was intermittently grabbing.

 

[vwtdi04]

the commutator was worn, but still look good for 190000 km, but most likely need to change the alternator, pulley is good , notice once I accelerate the car, light came on.
As soon RPM dropped light went off so time for new alt..
Thanks guys

 

[vwtdi04]

One quick question, can i upgrade to 120 amp alternator with pulley ?
Any modifications I need to do ? or this is direct swap.