I know this is an old thread, but maybe this will help someone.

Hope you were as lucky as I was:

I had this issue for a year, started a year after I replaced the original batter with a Diehard. Sears checked it, tested 12.6V this June. Alternator charging 13.5 - 14 V on my plug-in voltage meter.
Also had replaced Aux battery for the second time.

Recently while driving across Eastern Colorado heading to the East Coast (middle of nothing for many miles in any direction) the big red electrical warning came on saying something like Electrical Failure, Visit Workshop.). Freaked me out!

First thought was that belt broke. Nope, it is almost new, and was OK.) Turned off the car for a few minutes, turned it back on, and the light went out, and neither message has ever resurfaced - we spent almost 50 days on the road, 8600 miles, never topped off the oil. 112,000 miles now.

Great road car, just gotta keep that freaking electrical gremlin away.

 

Main Battery is toast

 

12.06 volts is low low should be 12.6 v min
580 CCA is too small for your car look at 750cc plus if you live in cold weather

 

Sorry for the typo.

It was battery voltage was 12.6, not 12.06 before starting the car.

When I replaced the original battery that was 12 years old, it was 11.5 and still starting fine. Of course I live in a mild climate.

 

PeterLech, presuming the alternator is the OEM, then with 110k miles, just replace it is my advice. I ended up sorting the problem with a replacement alternator. Per several YouTube videos I was going to just replace just the (VR voltage regulator). And remain convinced this would have been fine . . . for a while. Thing is, I like working on my own cars but I'm not poor and the delta between the voltage regulator and the whole thing - especially when compared to the PITA factor - led me to pony up the difference. This, largely because I'm not stupid either and getting dirty doing pretty much the same job once again in six months or a year means wasting my time (and getting to the VR is nearly as much trouble as replacing the entire alternator no matter how easy it looks on YouTube). Anyway, I'm old enough my time is too valuable to waste. Note, the icing on the cake was the forensic examination of the alternator, which persuaded me this was the right decision because of a) the state of the brushes and b) that of the commutator ring. Sometimes, being cheap can be stupid. In this instance, replacing alternator and voltage regulator combo was a no brainer. No more messages. No regrets.

 

Just curios jbeech, when you replace brake pads, do you put new wheels on the car?
Brushes are the only wearable on alternators and comparing VR to whole alternator price - on W211 you will find hefty difference. Why throw away good alternator only becouse short brushes?

 

Hi kajtek1,

Thanks for sharing your thoughts. Perhaps I didn't make it sufficient clear, but in addition to the brushes being worn, the commutator ring was in poor condition. Honestly, after 135k miles, I didn't feel it owed me anything. However, I made this decision 'before' disassembling the brushes from the alternator. The reason is; I am sufficiently experienced to have a pretty good idea regarding what I would find once I looked. Thus, I stand by my advice to replace the alternator because his automobile, with 110k miles, is probably in similar condition. Finally, please note; it's my opinion comparing brake pads and wheels is a faulty analogy. More apt would be; brushes-are-to-the-commutator what the pads-are-to-the-brake-rotors . . . and yes, I often discard the rotors when I install new pads because turning them will bring them below limits. Same thing happens with the commutator ring within an electric motor (which is what an alternator actually is) and the ring often cannot be turned on the lathe and trued sufficiently. Added to which, the bearings have a lot of experience after 100,000 miles and should be replaced, the insulation in wire (for the phases) may very well be nearing fracture (leading cause of shorting) because accumulating +100k miles involves a lot of year and lots of heat cycles. Like I said, basically I felt/feel replacing the entire assembly is a prudent course of action. Especially when taking into account the value of my time.

Respectfully,

 

When you can do whatever you want with your money, advising on public forum for spending big money when you have only small wearable that needs to be replaced tends to sound like spamming.
I drive high-mileage MB and the only time when brushes actually failed on family car was W124 with 275000 miles.
Can't tell for sure if the VR was original, but I suspect it was. Routinely when I buy 150k miles car, I replace VR as it is only common that you have drive to do lot of prevention on new purchase and later on you tend to neglect it.
But modern alternators tend to run for well over 200k miles before brushes wear.
Obviously commutator inspection is advised, but real life shows that most of alternators can wear several sets of brushes before anything else happens on them.
From my industrial experience, we had huge electric motors who run for 24hr/7 days a week for 40 years with only brushes replacement and commutator cleaning. Every 20 years a bearing would go bad. That was commutators with groves, when alternator has smooth rings.

 

FWIW, I bought a regulator on ebay - it was a new original Bosch part, cost under $35, delivered. Shipped from Latvia !

Still haven't installed it however.

 

Let us know how it goes. On the M272 engine which you have, it's not the same as the pre-face lift. I think you have to take the alternator out in order to replace the regulator and if you do that, you mind as well replace the whole thing. Mine went out at about 90k, had a burnt electrical smell to it, it wasn't just the regulator, bearings were also shot.

 

For some time MB brand VR were coming from India.
When in-line engines usually have good access and you can replace VR without removing the alternator, on V engines not only you need to take alternator out, but also disassemble additional parts to gain clearance for removal.
However you can also check for alternatives. When I was replacing VR on OM642 engine, I would have to remove lot of engine attachments to pull it out, but instead I dropped alternator into space on the side of the engine and after turning back of it up, I had good access to VR.
New design also has brushes holder, so it is easier to install.
I always advise for anybody who has more than 100k miles on the car, to keep VR replacement on short list. When you do other job on engine, replacing VR is not a big deal, but if you neglect it and get stranded - the consequences often make 4-digits expenses and big loss of time.

 

On my 2005 E320 the job looks to be easy but even with my smallish hands, in fact getting to the aft end of the alternator was looking like a PITA (pain in the hind end). Anyway, after watching several YouTube videos I realized just removing the alternator was probably going to be less work (and removing it is actually a fairly quick and easy job - took time to replace the serpentine belt whilst I was at it and examined the tensioner pulley bearings, too while I was at it). Anyway, like I said, this was mostly to avoid having to do this job again being why I deciding to replace the alternator and VR together. Far from spamming, this was just me judging 'my' best move and sharing my reasons for why. Your mileage may vary but I guess it's a matter of how you value your time.

Note; I enjoy working on the car - for example - I replaced the rear air bags myself. And that was a fairly straightforward job. However, I've taken it to the mechanic to have them replace the engine mounts - but they've done it twice and soon thereafter (6 months) they are a problem for me again. So I've ordered them once again (RockAuto, some German brand, I forget which, but definitely not the cheapest - perhaps the most expensive, I don't recall). Anyway, I'm going to be forced to try doing the engine mounts myself because it appears my mechanic just cannot get it right (and the dealer quoted me $2000). Similarly, I replaced rotors and pads myself, again, an easy job. The point being, I may not be a professional but I do have experience and getting to that VR looked like a pain. Anyway, sorry for the thread drift.

Finally, Krzysztof, it never occurred to me you'd be working on an inline engine. My 230TE several decades back was an I4 but ever since, engines in my vehicles have been V configuration and as you note, getting to the VR is easier with the alternator in hand. I suspect my trouble-free W463 will be next because it is just over 100k miles.

 

Here is a picture of my new and old voltage regulator at 135k miles. This is on my 2006 cdi.
Mike T.

 

What's eye opening is a peek at the commutator ring. In the case of the alternator in my wife's car I was happy to have replaced it. By the way, I wish I had known of this issue when I replaced the battery the first time. It went less than two years! I was fortunate the fellow at AutoZone looked at the calendar date on which I purchased it and warrantied it (3-year battery). The next time I wasn't so lucky because they only offered me a 2-year battery when I replaced it. Thing is, the OEM battery went seven years! Anyway, we'll see how long this battery lasts. The car is basically a daily driver whilst everything else is hit and miss because I have so many choices for wheels and very little real need so it may be weeks between uses for some of them.

 

You should just get the motor mount kit from Fcpeuro. Lifetime warranty so you don't have to buy them again. There's been discussion in the past as to which were OEM and I think the ones they sell are the aftermarket OEM makers of the mounts.

As for the alternator. You're doing it correctly. Most people just replace the alternator and get a lifetime warranty instead of just replacing the voltage regulator. If you have a lot of time on your hands, then maybe replacing the regulator makes sense and then you can just replace the alternator later when other bits of it go, but if the original lasts you close to 100k, you would hope that the replacement might last as long so you don't have to worry about it for a while.

 

Thanks for the tip regarding the engine mounts. I dread this job because it doesn't look easy. I read how on W211 it helps to remove 4-bolts mounting the steering rack and allowing it to sag/hang by the Heim joints because this creates sufficient clearance. Anyway, and once again, sorry for hijacking this thread. Please feel free to redirect me to a better thread on engine mounts via PM.

 

I Have A 2006 W211 4 MATIC, My Low Function LIght Comes On All The Time, I Do Not Drive The Car Very Often, I Put It On A Charger & It Charges, I Do Not Know If I Need A New Battery Or Not, THe Car Only Has 44k Miles On Her & She Looks Brand New, It Has The Original Battery In The Trunk, I Was Just Going To Buy One & Forget It Any Thoughts Why This Is Doing This, I KNow I Don't Drive It Enough, Its Mostly In MY Heated Garage & Has Never Seen Rain Or Snow, I Am Puzzled ????

 

Replace the battery 17 years on a battery is fantastic, but it is due after approx 8-10 years sitting on a charger when the car is parked and sits

 

The 2006 has an aux battery in addition to the main battery. That probably also needs charging. The aux battery is for the SBC brakes in case the main battery goes as that's a brake by wire system. Charging the main battery won't charge the aux battery. Find the aux battery and put a charger on that too. Also the 2006 has the M272 engine which had bad balance shafts that year. But with such low mileage, you might have a while to go before you encounter it. Many threads on here about it. Might not affect every car so you might get lucky.

 

If you have SDS you can see perhaps there is a drain on the battery. I think there was a thread about how the infotainment/stereo/CD player can drain. Mine also gives low convenience after 4 or 5 days of sitting with both batteries replaced so I know it's a small drain somewhere just haven't cared to look after several years.

 

So Do You Think The Battery Is Still Good, If I Disconnect The Charger It Quickly Goes Down In Charge To LIke 80%

 

If this is the original battery, then it is time for replacement, we are talking 17years old, also if there is an aux battery replace it also
Replace it with a AGM style battery or in 3 to 4 years you will need to replace it again if you use a normal lead acid battery

 

An old battery places higher demands on the alternator when it does start and will possibly cause this to fail because it is constantly charging on the battery
For complete confidence, pull out the battery and take it to auto parts store and get it ( battery) load tested, but at 17 years old I would not want to be stranded somewhere knowing that the battery will not start the car

 

If I Take The Charger Off & Let It Run It Will Maintain The Charge, But When I Go To Start The Car It Does Not Start Until Like The 3rd Try, I Get Nothing When I Turn The Key To The On Position & Then It Will Turn Over & Start ????

 

how are you typing like that?

uh yeah the batteries toast. They go out every 3-5 years depending on maintenance. The battery is it's own machine it has upkeep requirements and is in a constant state of entropy. If the thing won't stay above 12v as soon as you stop the car the battery wants out. Starting your car with low battery will cause many of the nonessential modules to fail to start up and the ECU doesn't bother to energize them.

AGM H6 or H8 will work. I have no idea why the cars have two battery sizes that both work but that is not exclusive to Mercedes. If you can buy the 49, buy the 49. The charge depletes over time from parasitic draw, once a battery is like super depleted then it starts taking damage. Once you've drained a battery to nothing it doesn't hold a full charge again and this abuse over time pretty much ruins them.

Thats group 48 and 49, the H8 is slightly longer, but it fits. Costco has the best deal on batteries, it's like $190 for an H8 AGM.