On my 5th Bosch alternator in a year

Hey there everyone,
I'm writing about my beloved MK3 Jetta TDI and the troubles I've had keeping good alternators. Shortly after buying the car a year ago, I started hearing some grinding noises. It was the front alternator bearing. As it was recently replaced by the previous owner, the warranty was transferable. The new one went in fine and all seemed well for a while. Then it happened again. Rinse and repeat to alternator #3.

After going through 3 alternators (front-most bearing), I started thinking something must be causing this issue and it can't be just bad luck with alternators. After more investigation, it turns out the bearing on the AC compressor is toast as well. Perhaps it was causing the alternator bearing to have such a short life?

It was about time for a timing belt, so my buddy SootHappens and I decided to change the whole lot. Timing belt, Idler, Tensioner, Water pump, AC compressor, Serpentine pulley, and yet another Alternator.

All was well, it ran great! Until 4k more miles, when, you guessed it, the alternator bearing is toast again. What is going on? I'm looking for ideas, and thanks for listening to my story.

-Blake

Timing belt, water pump, power steering would have nothing to do with it. Perhaps the serpentine tension is too tight? Did the alternators have clutched pulleys?

I assume your parts source was swapping reman's with you, not brand new parts. It's possible those units didn't get rebuilt with new bearings.

Does the tensioner arm move freely with no jerking and is it rock solid? If it's moving I'd replace the serpentine tensioner, roller, and harmonic balancer. Try removing the tensioner and see if there is any play in the shaft, the bushings may be work out or seized.

And are these alternator replacements Bosch or Valeo? If Valeo, definitely run a Bosch.

Had the same problem with the Bosch rebuilds on a B4 but I stopped at two.
Front bearing went south real quick. Probably never changed or cheapo bearing substitution.

What about crankshaft dampener? Is it out of alignment with the alternator? Is the crank pulley separating? Wrong size belt? 6pk1143 (going from memory so bare with me)

1145, from my memory