Yeah, those old S-Class use a ton of current from the battery. Not having a 100% good battery can get you in trouble in a hurry. Not having a good alternator can ruin a good battery very quickly.

Double check your main ground connections and make sure the battery terminals are pristine before driving very far on your new battery. Last thing you want to do is ruin a brand new battery. Also check the connections at the alternator. You could just have a bad connection.

Curious, does that model have the removable brush assembly, or is that just the older diesels?

-tp

Had the hardest time getting the pulley off the old alternator. Ruined a large hex key that I had here in the effort, but took it back to Kragen and they took off the pulley with an impact wrench and put it on the new on in no more than 10 seconds! Gotta get me one of those!!!! Anyways, they tested the old alternator, and although it was supplying more than pleny enough current, it failed the test three times. Some sort of "filter" or similar had probably failed inside the old alternator due to the high production of electricity I was told.

Got the new alternator and the now fully charged battery in, and got the family to a Christmas party in time. Will double-check the connections to the alternator tomorrow and re-test the battery just to be sure.

Not sure about the removable brush assembly - rebuilding is a little advanced for me just yet.

Thanks for your help on this!!

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1988 560 SEL
1984 190D 2.2 (Sold)