Alternator Bosch or AC DELCO

Bosch makes (made) excellent rebuilt alternators and I’d check them out.

I bought a Bosch alternator at O’Reilly’s for ~ $300 and the gaskets at Autozone for ~ $100 (you can get them cheaper but I needed them quickly)

I would use the BOSCH from fcpeuro.com without hesitation.

On that list, I'd only go with the AC Delco.

Only brand here I am confident with is ACDELCO, Wai I’ve installed due to customer already having the part but I cannot swear to its reliability.

I replaced my alternator two years ago, and I put in a Bosch, and I haven't looked back. It works great and also has a warranty.

I own the exact car, when I bought it, it came with a bad replacement alternator. The replacement was an eBay brand which was causing all sorts of faults. I replaced it with a Bosch unit and the car seemed fine. A few weeks after the replacement, I started getting a random limp mode with various under and over voltage errors. At this point I decided to buy and install a BMW branded alternator. This took care of issue.

I tried to correct with a new and proper group size battery - it had an OE 140A Bosch alternator and starter with a 2016 El Cheapo battery that was one group size too small so I replaced the H5 with a new H6 group and all was good for a few days... I also replaced the starter just because I like to spend $ and wanted a clean slate as this a vehicle I intend to keep and drive daily as needed. The new battery/starter work great but I noticed right away that the voltage while at idle was now almost a full 2 volts lower than before changing any of the afore mentioned parts. I have a P3 dash vent gage that reads to 0.1V and I use a VOM plus VCDS so I know the P3 reads OK. Before changing any parts the P3 read 13.5 to 14.4 volts steady depending upon what accessories were on. After the H6 battery the P3 read 11.5 to 12.5 volts under the same driving conditions. I tried to get the OE alternator bench tested but that did not work so I just went with a new reman Bosch unit. No change in voltage with the new alt... So this past weekend the motor fired up just fine and the dash vent P3 gage display was 12.5V but while driving around town running errands the voltage kept dropping all the way down to 9.0V which caused the DSG to lock and basically leave me stranded miles from home. I will try to get the entire electrical system load tested this weekend but for now I just keep a tender on the batter at night as I do not drive much during the week nor do I commute. The tender keeps the battery at 13.0V reliably.

I was driving the Mini when the engine began to struggle at idle and then shut off, refusing to restart. The starter engaged but hit a wall of resistance. After getting it home, I found the alternator was completely stuck. The one I replaced was a Bosch. Its bearing had failed catastrophically, and the pulley would not move.

Ive had a few Bosch reman failures lately at my shop as well, although they were for N52s, all bearing noise after about a year.