Owner reviews for alternator

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

They're the only ones who make an aftermarket alternator that won't give you charging system issues with Acuras.

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.

Replacement is absolutely fine as an option, but I recommend going with a genuine brand as originally specced for the vehicle (Denso, AC Delco etc). Some aftermarket brands like Jaylec (just an example of brand, not quality) aren't built to the same standard and can be underpowered.

Both Valeo and Bosch are good brands. I’ve never owned a Mercedes, but both Valeo/Bosch are installed in various BMWs from the factory.

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.

The alternator was replaced, car died again two weeks later. The Valeo OEM was deemed defective. Back in the shop for a warranty change, still getting voltage fluctuations.

All I could recommend is stop buying the autozone/duralast alternators. Buy a good brand, ie Denso, Delco, Motorcraft, etc. and return the duralast one outright for cash in hand.