Voltage
I think alternator voltage regulator on its way out


https://mbworld.org/forums/c32-amg-c...-problems.html
Morphh - i just recently went through this too with my Valeo alternator which died at 116k miles. i had a local pepboys install a garbage Reman Bosch unit that couldnt hold 12.5 - 13.0 V while driving despite being new which i had heard was the case but i was in a jam and had them put that unit in.
i found out you can replace the voltage regulator on the Valeo alternator and its pretty cheap and easy (assuming you have the alternator already out) to do with just a few screws. The link above shows pics of the new valeo VR compared to the old VR that i replaced.
i had my indy shop put the old Valeo back in with the the new Voltage regulator and its been working great. starts out at 14.2 and then with AC on and lights it stays around 13.5-13.8 while driving around. if im stuck in traffic with the AC on it does drop to 13.3 - 13.5 which I'm not worried about.... that reman Bosch unit would drop to 11.5-12V in traffic and was terrible...
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when mine died, i got one initial warning while driving "battery/alternator visit workshop" and the volts was below 12 and it stayed there for a day of driving.
but the 2nd time it came up the next day i had about 10 minutes driving in the car car and the volts died to below 10 and immediately the alternator was dead while i was out on the road and had to get it towed to the shop...
if your volts is staying at 13 or even 12 you probably have some time, but should get it checked out.. if its at 11 when driving then for sure get the alternator checked as if its like my situation its near dead and can go anytime leaving you finding a tow.
cheers






