Crna Mechka

At first I thought it was the battery...then the alternator...and finally the actual culprit.



Very inexpensive part that seems to commonly go bad in our cars.

shaystudies

yes! just got mine fixed! my car was having power issues due to this and had to drive 45 miles with 9.0Vlts really scary.

contact148

where did you buy that part??

phister

Think from autohausaz I couldn't find the part on rmeuropean or mymercedesparts. Unless the OP wants to shine light on the part number. Based off the picture its 30097 on autohausaz but its not linked to our cars. Unless it's just bring used as a reference

Crna Mechka

Phister has it right, the picture is just for reference.

And although it's cheaper at RMeuropean (yes they do stock this part, at least for my model MBZ), I purchased the part at Autopartswarehouse. It's an OE part made by Bosch # 003-154-97-06.

Piece of cake to replace too.

phister

yeah my model doesnt have one

screech

My 2008 c300 4matic appears to be having power spikes that reboot my systems. Loose ABS and ESP, the dash display shuts off, wild stuff. Indy mechanic found one fault in every system and thinks the "alternator is overcharging". But this event did not happen at high revs, and it is sporadic. He is trying to sell me a rebuilt alternator, i bet is simply the voltage regulator. How is the regulator replaced? Any DIY?

pcy

Typically, voltage regulator is attached on the back of alternator. You will need to remove the alternator from the car, then remove the VR. If you are going to remove the alternator to replace VR, have the alternator checked and see if the bearings and/or brushes replaced. You wouldn't want to have to go thru this again...

Below picture is of an alternator from BMW. But you get the idea...

gthirty6ptime

what symptoms are the cause for replacement of this part.

pcy

With properly functioning alternator and voltage regulator, output voltage [with engine running] should be just above 14V and should be stable, not fluctuating erratically. If the voltage is higher, then VR needs to be replaced. Over-voltage can kill electronics. Not all electronics have over-voltage protection.

SeaCoupe

I have so been here before. In two ways. As a sucker who paid the dealer $1,200 to have the alt replaced, and as a savy diy mech who only need an hour and a half and $60 to replace my voltage regulator.

A bad voltage regulator can show up as under or over voltage. Under voltage will show up on the dash with a warning about low voltage. With a volt meter, you'll read under 12 odd volts. Over voltage will show up as errant system failures. Personally, I have never seen an over voltage warning light.

The regulator is on the back.

To get the alt off, you need access. That may include, removing your air cleaner assembly, and belt tensioner. I found that removing the passenger side sway bar gave me better access. I then pulled the retaining sleeve forward (I think) so I could drop the alt. Once the alt is off, pull off the rear cover.

My alt had some corrosion which had the screws holding on the regulator quite stuck. I used a 5 min soak of PB blaster to free it up. Pull off the regulator assembly, and install the new one.

I know people talk about checking diodes and bearings. I spun the alt once I had the belt off and didn't hear any issues with the bearings. As in it was smooth. No whirring. The diodes, I figured it was either going to work, or not.

On my car the 2002 Coupe with the M111, I think someone with good hands and dexterity could do the work on the car.

If your car has more than 75k miles since the last alt. work, I would definetly say replacing the voltage regulator is on the maintenance list. Could you get more miles out of the old regulator. Maybe, but why get stuck somewhere?

polarbexar

I just went over 200K miles on my 05, I ordered a rebuilt alternator (Bosch) my Valeo is giving it up finally. No message, just fluctuating lights and the radio and hvac has started to cut out...

DaODB

I bought the brand new Valeo, and I was getting the message with no other symptoms, not even a dead battery. The voltage was low, but car running fine.

I questioned my mechanic if I could change the voltage regulator, and he kind of laughed at me and acted like I didn't know what I was talking about! Oh well, car is running now! I still have my old alternator as sort a keepsake, though

Crna Mechka

What seacoupe said.

-If the voltage is fluctuating then a likely culprit is the voltage regulator.

-If you are simply losing juice after driving, the alternator is not doing its job re-charging the battery while the belt system is running. In this case I would check both the alternator and its pulley.

-If your battery is losing juice while ideling (key in position 1 or 2) then your battery likely is kaput (which was the case with me, along with voltage fluctuation).

Hope that makes sense.

Crna Mechka

Heh, time to find a new indy maybe?

DaODB

Maybe so after what he is telling me about my upper radiator hose. We'll see the responses from the forum posters, though.

And my case applied to: "If you are simply losing juice after driving, the alternator is not doing its job re-charging the battery while the belt system is running. In this case I would check both the alternator and its pulley." So perhaps he was correct. He states he started working in Mercedes of Jacksonville. I started going to him after they treated my brother very well (although, he has a Ford!)

My voltages stayed around 11V no matter what, so the alternator was doing no charging at all. He did the load test and then said the alternator was the culprit. That's when I stepped in and asked if the voltage regulator should be checked because I saw some talk on the forums, but he laughed and said something along the lines of old cars...

screech

Good indys are hard to find. Low voltage reading at the battery terminals while the car is reving 2-3000 rpm, most likely alternator. High voltage, or spikes, would mean voltage reg. is not doing its job.

Thanx SeaCoupe, good to know. I'm going to try DIY if my indy guy cant or wont replace the VR.

Looking for diagrams or videos