cmarcho

I have had the 'battery/alternator' warning light come on a few times now. The message clears when I turn the car off but after a few days it will come on again. Today while driving I noticed electrical whine in my stereo. I'm guessing it might be the alternator going bad.

How hard is it to change? Where is it located? I haven't even looked.

Boom vang

if you do a search you will find lots of information on this. Here is an excellent post, I also added my own comments on it based on my experiences

https://mbworld.org/forums/c-class-w...t-attempt.html

.

cmarcho

Awesome! Thanks. So it doesn't look too bad, just a lot of time and patience.

Boom vang

sounds like you need a new voltage regulator. Go to http://www.americanenginesco.com/servlet/StoreFront
and contact them for the correct one. I believe that you car will have a Valeo Alt in it. This is the part and price for the one I put in my 2004 Kompressor. I have had mine in for a month and cleared up all the issues that I was having. Make sure you clean the split rings to perfection when you put the new VR in


American Engines Corp Items
1 BMW 3 SERIES Z4 Mercedes Benz C Alternator Voltage Regulator OEM @ $59.45 = $59.45

Sub-Total: $59.45
Shipping: $10.00 (Standard Shipping)

ambit

Make sure you disconnect the battery or you'll be in a for a big surprise when undo the nuts on the back of the alternator.

I unbolted mine from underneath and passed it up the front to my buddy.

Also make note of its orientation when reinstalling it. I was able to put mine on 'backwards' (housing was spun around) and it fit fine but wouldn't spin, preventing the car from starting.

cmarcho

whatever it is got worse today. On the way home, the light came on again. I stopped somewhere and as usual when I restart the car, it was gone again. But shortly after, the radio and a/c cut out completely while driving but came back on within a second, and the light came on again.

Made it home without any other issues, but my 45 minute each way commute is going to get real long if it decides to die on the way to/from work. I may use one of the $100 parts coupons and pick up an alternator from the dealer if it's not too high. Since it'll have the voltage regulator on it, I would rather just replace both since I'm going through the trouble of pulling it anyway.

JFarhanbod

i paid 350 to get mine done today (just labor). i know it was a rip off but the mechanic is a good friend of my fathers. it took about 4 hours from start to finish lmao

Boom vang

good friend or not, I don't think the mechanic knows what he is doing or the 4 hours included lunch, smoke breaks, several bathroom breaks and a nap. I am no mechanic but it was about 30 min to take out, 15 min to remove the VR and clean the split rings and install the VR, and another 30min to put back in the car to close the hood and drive off. If I had to do it again I probably could shave about 20-25min off the total time

Boom vang

The dealer will only sell you a brand new one, a Bosch is about $800 and a Valeo is about $1200. If you have a Valeo 90% of the time it is the VR that is giving you the problem. Find an auto electric place for them to rebuild it, no one replaces with a new one other than under warranty. A rebuilt with run you about $300


http://www.americanenginesco.com/ser...C-Class/Detail

LILBENZ230

How many miles does your 05 have? Put it in dyno mode and see what the voltage is doing as you drive.

cmarcho

Just over 70,000. How do I put it in that mode to check?

Boom vang

this sometimes does not give you the real picture, my readings were all to spec but still getting an error message, once I changed the VR it cleared up all those problems. Even when I checked with a multimeter

If it is a Valeo Alternator, they had a bad batch of VR for the 2004/05 models

perhaps you have a dying battery as well

cmarcho

I picked up a reman alternator today. Dealer wanted $500, don't know if it was new or reman. So I got a parts store alternator for $200 and will give up the $39 core to keep my original. I'll probably get the VR and then keep the Valeo as a spare alternator. If the reman fails, it has lifetime warranty, I'll put the original back in with the new VR and try to get a refund on the reman.

LILBENZ230

It will be interesting to see if the parts store alternator is rejected by the car or not. If the car has a Valeo alternator, we've had 05s reject Bosch replacements.

BTW - Dyno mode's voltage read is not there as a toy, it's a real diagnostic function. It never hurts to utilize it. Cmarcho, please search the forum for instructions on accessing the menu.

cmarcho

what do you mean by 'reject'? Will the alternator not work? Or will there be a service engine light?

with all the issues I'm seeing about disconnecting the battery, I may try to insulate the wires when I disconnect them from the alternator. Anyone ever tried that?

LILBENZ230

I've read more than once on here, specifically 05s, have not been able to use Bosch replacements for Valeo originals. It fits, but doesn't correct the issue.

cmarcho

ok, I am thinking I will not use the part store alternator.

I went to order the VR and this is actually the correct one for my car:

http://www.americanenginesco.com/ser...C-Class/Detail

I pulled the part number off the back of my alternator, it's a Valeo A 271 154 09 02

So this is on the way, going to take the alternator back for refund today.

I just hope I don't harm anything when the light comes on while driving.

I did find a new Valeo alternator with the same part number on the internet for about $300. If the VR doesn't fix the issue, then I'll get a new Valeo.

I'm more worried about disconnecting the battery and all the issues that will come from that than I am replacing the VR.

Boom vang

that is the VR that I put in, guess the price went up by $10

No issues with it, make sure you clean the split rings with alcohol or a MAF cleaner before you install the VR

I posted this source many months ago as I found it the cheapest for OEM Valeo VR through my search. They are very helpful there.

the part is $202 in Canada at MB; $170 at MB Buffalo; $120 at Annapolis MB

Best deal around


I ended up with a SRS error when I rehooked everything back up and $80 later I had it cleared with a Star Diagnostic

cmarcho

ok, on my 2005 c230 to enter dyno mode, you turn the key to position 1 and immediately hit the reset button three times. It instantly goes to dyno mode and the voltage is showing.

Before starting, it's at 12.5v
After starting it's around 12.9 to 13.2, this is with headlights and a/c running.
Driving around it's still around 13.2.

So, is it the regulator? Or is the alternator failing?

cmarcho

Update:

I put it in dyno mode on the 45 minute drive to work.
Still 12.4v before starting and 12.9 after starting, but it did stay steady around 13.8v while on the road driving to work. It would drop back down in the 12's at idle. Didn't see the light come on during that time.

Boom vang

normal is
12.9v engine off
13.9 at idle
14.2 at 2000rpm

there should be a full 1 volt difference between idle and the engine off. The Volts will be in the 14 range when the car is running at regular rpm. It should never be over 15v

cmarcho

Aha! I finally caught it.

On the way home, voltage was around 13.2 or so, and then it started spiking back and forth between 12 and 16v!!! That's when the warning light came on, and after that is stayed at 12.4 volts until I turned the car off. Once I started it back up, it was around 13.x again.

LILBENZ230

As I said, dyno mode is extremely useful for this stuff. Sounds like your VR is definitely having issues. My 2005's values are:

OFF - 12.3V
IDLE - 13.3V
2000RPM - 14.1-14.2V

Close to normal, to be expected with 114.5k miles on the alternator and 6.5 years and 114.5k on the original battery.

cmarcho

FINALLY!

I got my voltage regulator on Friday evening but the weekend was busy and I didn't get a chance to work on the car until around 11 tonight. I almost put it off another day but the spikes in voltage to 16v were scaring me.

It took me about 90 minutes because I am slow and meticulous!

What a pain in the butt to get to all the stuff. My back is aching from leaning over the whole time, but I did everything from the top.

I put it all back together and waited a couple minutes after connecting the battery cables.

Turned the key, started it up, no codes!!!

nice and steady around 13.4v at idle. I just cleaned up and showered, going to test drive it real quick then get to bed since I get up for work at 6:00.

I called the dealer today to see how much for them to install the VR, they said they don't install anything unless I buy it from them. They said a VR was $220 and labor was $350 to install it.

so I paid about $75 with shipping for the VR and put it in myself. I saved $495 tonight.



==============

morning update:

Drove to work, voltage before start was 12.5 or so, started and it was 13.4, after driving, it was solid around 14.2 most of the time, 13.9 sometimes. I could see a big difference in the voltage being higher and more steady as I drove.

Yesterday it would fluctuate constantly between 12.9 and 13.8 while driving, then it would have the bigger issue of spiking to 16v and that would cause the radio and a/c to cut out and the error light on the dash to come up.

t4pizza

I have the save alternator battery visit workshop light come on, so I read this forum and did the diagnostic which is as follows:
12.4
13.4
14.2
This seems to be in the normal range, correct? If that is normal and the alternator is working fine, what could the issue be? I replaced the battery about 6 months ago and I haven't had any issues with it charging or keeping a charge. This has me baffled. Thanks in advance for any advice that is given.