Alternator/ Battery Visit workshop

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DSM10000

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The C320 was fired up for a quick trip into Salisbury this evening of about 7 miles, but it has been used several times this week for journeys of 18 miles or so, part way through the journey this evening a warning stating Alternator / Battery Visit Workshop was displayed.

I managed to get to my destination and back and on my return I checked the battery voltage with the engine off and with it running, no difference, both readings circa 12.3V.

The drive belt is still in place and seems well tensioned, no belt squealing is evident so to my mind this points to an alternator failure?

Does this sound like a reasonable diagnosis?

Thanks as ever.
 
This sounds like the beginning of the end for the alternator, I had the same symptoms on a couple of previous W211's and it turned out to be the alternator.
 
This sounds like the beginning of the end for the alternator, I had the same symptoms on a couple of previous W211's and it turned out to be the alternator.

Thanks Lee.

It looks like a simple and quire accessible job, I may order a replacement alternator and change it myself. I quite enjoy getting my hands dirty occasionally. :)


ECP etc show several brands, two I have never heard off so I am tempted to buy the Bosch, it is not much more expensive once you
claim back the surcharge.

Have a great weekend.

David
 
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An auto-electrician will recondition your alty for half the price of a new one often while-u-wait.

Thank you for taking the trouble to reply :)

A new Bosch from ECP (Not the cheapest but just a guide) is circa £154, with other brands from around £120 so not that expensive.

The MB has become a "hack" car at 12 years and 140,000 miles but it is worth keeping on so will probably buy the Bosch.
 
This morning I decided to have a check over all the connections to the alternator and battery. All seemed tight so I slipped the drive belt off and turned the alternator by hand, no roughness or any noise.

Having put the belt back on and having charged the battery for about half an hour as it had dropped to 11.5 V this morning I started the car and checked the voltage at the battery once more, it is now reading a stable 14.4 V and only drops to 14.2 V with the dipped beam on.

I assumed alternators worked or did not, could it be failing due to overheating? It sits in a good airflow so cooling air is not an issue.
 
Might it be just the reg pack starting to fail? Is yours one that can be swopped without removing the alternator?
 
Might it be just the reg pack starting to fail? Is yours one that can be swopped without removing the alternator?

Good idea!

I am unsure, I cannot see a part number on he alternator.
 
I have a 2004 E320 CDi and about 2/3 years ago I had the same warning light come on but for me the light stayed on permanently. I took the alternator to a local repairer who replace the regulator for about £40. I have had no issues with the alternator since. My Bosch alternator part number is 012 154 9802 and the regulator number is BR14 M0. You may be able to replace the regulator in situ but I would recommend removing it if your access is the same as on my car. Hope this is of some help.
 

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