voltage regulator issue
Thread Starter
Junior Member
Joined: Mar 2011
Posts: 23
Likes: 0
From: SF Bay Area
2004 c 230K and 2014 SLK 250
voltage regulator issue
Hi everyone, so I got 2003 c 230 coupe 149K , lately I'v been having warning lights " light sensor visit w/s , esp warning ect" so I researched a little and it seems to have associated issue with the battery. I checked it and found pos term leaking fluid around , anyhow before that I used secret menu to watch battery voltage on display. so at start 11.1-12 v, and idle 13.7 V and reved up a little 14.3-14.4 V. It all looks normal but one time at start I saw voltage spike up to 17+V for a second or two and then came down , and all warning light came on . after restart car no more warnings lights. I changed the battery with oem MB ( got a deal 134$ ) and started car and bam- warning lights came back on 
. I think maybe voltage regulator is going out, no sure if I have valeo or bosch alternator. Anyone had this issue? Tnkx in advance.
. I think maybe voltage regulator is going out, no sure if I have valeo or bosch alternator. Anyone had this issue? Tnkx in advance.
Junior Member
Joined: Aug 2016
Posts: 58
Likes: 13
W203 c200 Kompressor
could be a clutch pulley that is on the alternator, they tend to seize and cause problems. Here is a video of how to test and remove it (I used this to help change mine , my car is m271 engine c200 kompressor)
MBWorld Fanatic!
Joined: Jun 2002
Posts: 7,258
Likes: 168
From: So. Oregon Coast
C230 Sport Coup + 2006 W164 ML350 + 99 Ford Escort RIP
If you've got 149K on the original Alternator, I'd pull it and have it rebuilt.
About $200. Better than waiting for it to fail, which it will, guar-an-teed,
just like they say in the commercials. 149K would be a record for me, if it was my car.
They always seem to fail right around 120-130K. And then....you are f'd!
I hate breakdowns.
I still have my old voltage regulator, which was fine except the brushes.
Just had new brushes put in ($25) and ready to go...
but that won't work if the regulator itself is going out.
About $200. Better than waiting for it to fail, which it will, guar-an-teed,
just like they say in the commercials. 149K would be a record for me, if it was my car.
They always seem to fail right around 120-130K. And then....you are f'd!
I hate breakdowns.
I still have my old voltage regulator, which was fine except the brushes.
Just had new brushes put in ($25) and ready to go...
but that won't work if the regulator itself is going out.
Newbie
Joined: Jan 2016
Posts: 11
Likes: 1
From: NJ, USA
W203 C240 6MT
My alternator failed at 120k mi I had the same warnings as you and also a parasitic draw on the battery that I couldn't find anywhere.
I bought a used Bosch reman off ebay for $90, replaced the alternator and it all went away. Car is 100% now.
If you don't want to gamble on used parts I'd say just buy a new complete alternator and call it a day.
I bought a used Bosch reman off ebay for $90, replaced the alternator and it all went away. Car is 100% now.
If you don't want to gamble on used parts I'd say just buy a new complete alternator and call it a day.
Super Member
Joined: Sep 2016
Posts: 571
Likes: 92
From: New England! :-)
2005 C230K Sport Coupe
I bought a new Bosch alternator from Amazon. Their price varies for that part. That's likely because of their automatic price matching.
I got it for under $250.
https://www.amazon.com/gp/product/B000EPSYHC/
Bosch AL0810N New Alternator
Price: $299.39 (as of 11/03/2016 -- 1am - EDT)
I got it for under $250.
https://www.amazon.com/gp/product/B000EPSYHC/
Bosch AL0810N New Alternator
Price: $299.39 (as of 11/03/2016 -- 1am - EDT)
MBWorld Fanatic!
Joined: Jun 2002
Posts: 7,258
Likes: 168
From: So. Oregon Coast
C230 Sport Coup + 2006 W164 ML350 + 99 Ford Escort RIP
Kessel,
try ADS in San Jose.
They only sell original OEM rebuilts, I think $90 with exchange.
Not some cheap Chinese made crap. I haven't used them yet, but
I'm going to soon. Starter making weird noises.
How old is your battery? Just curious.
try ADS in San Jose.
They only sell original OEM rebuilts, I think $90 with exchange.
Not some cheap Chinese made crap. I haven't used them yet, but
I'm going to soon. Starter making weird noises.
How old is your battery? Just curious.
Thread Starter
Junior Member
Joined: Mar 2011
Posts: 23
Likes: 0
From: SF Bay Area
2004 c 230K and 2014 SLK 250
not sure how old the battery,but my other c 230 ss oem battery lasted 10 years( not bad huh?). Anyways , sold my coupe to a friend's kid- he loves it, if this problem presists I'll help him change alternator( Valeo type). I miss my coupe
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MBWorld Fanatic!
Joined: Dec 2003
Posts: 3,275
Likes: 236
From: BC, Canada
2003 C230K Coupe Orion Blue
Just saw this thread. Had the exact same symptoms a few years ago. (Click here)
My money would be on your VR. I didn't bother rebuilding the alternator (against my mechanic's advice) but as the problem was indeed with the VR, I saved myself a few hundred bucks. Still on the original alternator, no problems at all.
To save you some work, this is the cheapest place I could find a replacement OEM VR. American Engines I bought mine from here.
To check if you have the Bosch or Valeo alternator, just look at the label. The alternator is directly in front (ie towards the front of the car) of the exhaust pipe. Just pop your head in there with a flashlight.
Good luck.
My money would be on your VR. I didn't bother rebuilding the alternator (against my mechanic's advice) but as the problem was indeed with the VR, I saved myself a few hundred bucks. Still on the original alternator, no problems at all.
To save you some work, this is the cheapest place I could find a replacement OEM VR. American Engines I bought mine from here.
To check if you have the Bosch or Valeo alternator, just look at the label. The alternator is directly in front (ie towards the front of the car) of the exhaust pipe. Just pop your head in there with a flashlight.
Good luck.
Last edited by slammer111; Nov 15, 2016 at 05:28 AM.
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