Alternator Bosch or AC DELCO

If it was me, I’d go with the ACDelco. Never had any issues with them so far. Checking for the best warranty is something else you might consider, just make sure to read that fine print closely.

Step up and buy a Bosch. Yes, they do fail, but the odds are much less.

Bosch is still the gold standard but not what it used to be. Don't buy cheap junk.

Stick with a high quality oem replacement alternator; VW installed a number alternator oem brands (bosch, Valeo, Hitachi, etc). My 2002 New Beetle Turbo S; had a Valeo 120 Amp unit installed, I had a hard time finding a Valeo unit, so I went with Bosch and so far, I have not any issues with it but the body of the alternator, was slightly bigger, so the wiring harness, was a bit of a tight fit.

You can get a Bosch alternator for a KA and swap the pulleys

Any time I see overvoltage faults I replace the alternator. Check the charging voltage and confirm that it's charging higher than 15.0v (it may happen only briefly under some conditions). If it is then unplug the connector from the alternator. That should default it to 14.3v. If it still overcharges then you've confirmed a faulty alternator.

Bosch rebuilt alternators are like $175 online. Lots of people experienced low quality rebuilts. Have people had good luck with Bosch rebuilts?

I pulled the alternator to have it tested at o'reillys. Test showed it was dead so I bought a reman'd Bosch, but still needed a jump. Car fired up right away, but the voltage gauge still read low and just slowly dropped until the car died again.

So, OK, ended up getting a Bosch Reman from IMC, installed it to find out it was only producing 10Volts @ idle. Took it back out, and installed an Ultima which put out 14Volts @ idle.

We have been having a lot of trouble with Bosch reman alternators and starters in the last couple years. Pretty sad, used to be great stuff. Now all the boxes say made in china and everything is crap.