Alternator question
Thread Starter
Junior Member
Joined: Mar 2014
Posts: 20
Likes: 0
2009 c63 amg
Alternator question
Okay guys, I have a 2009 w204 with 56k miles on it and I have a nagging suspicion that my alternator isnt completely at fault although it had an effect. I was driving my car home from a friends house when the battery light came on, shortly there after the radio truned off, followed by the safety features and then eventually the motor. Now I know that this was caused by the alternator but Im have heard the alternators on MBs are bullett proof. The reason for my suspicion is I drive a lot in Sedona, AZ (has a lot of dust and sand that blows into the engine bay). However, I have been reading that the voltage regulators on the alternators are notorious for going bad, before I pull the alterantor I want to get you guys opinion of the situation.
Thanks guys
Thanks guys
MBWorld Fanatic!
Joined: Oct 2007
Posts: 2,311
Likes: 382
From: Texas
10 C six trizzle
they are by no means bullet proof. also consider your car is 2009. production possibly in 2008 so your battery is going on 5-6yrs. If it's weak it will cause extra strain. I'd start with that first.
As for bullet proof parts.... rear differentials,axles, drive shafts and starters come to mind.
As for bullet proof parts.... rear differentials,axles, drive shafts and starters come to mind.
Super Member
Joined: Aug 2011
Posts: 688
Likes: 14
2013 C63 Coupe
The battery is used to start the car. Hence why battery are rated by cranking amps, etc. when the is running, the alternator/VR provide the proper voltage to the cars electrical systems by varying with rpm of the engine/alternator... Including trickle charging the battery. So your VR which has diodes that has a reverse current relay or bridge circuit suppose to recharge the battery after engine start... If it doesn't recharge the reverse current relay of the VR has a problem. If I am not mistaken the VR is part of the Alternator. Another problem is the commentator brushes on the Alternator are worn. But since your battery light comes on, your battery is taking up some of the load the alternator can't. So if the battery can completely hold a solid charge, after your have the alternator fix or replaced, I would think about getting a new battery as well. Changing alt brushes are simple.
Senior Member
Joined: Jan 2014
Posts: 462
Likes: 48
G63
You can do an easy check. Put your volt meter to the battery terminals and check when running and not running. It should be above 14v usually 14.7v when running if the alternator/volt reg are working properly. I bet yours will show less than twelve since you mentioned systems shutting down like the radio, etc. The car will run for a little while on just the battery if the alternator/volt reg are bad, but I wouldn't try going too far.
And yes, the volt reg is part of the alternator in your car so you're looking at replacing it.
And yes, the volt reg is part of the alternator in your car so you're looking at replacing it.
Trending Topics
MBWorld Fanatic!
Joined: Mar 2006
Posts: 4,278
Likes: 379
From: San Jose area
'19 E63S sedan
MB World Stories
The Best of Mercedes & AMG
7 Craziest Things AMG Gas Ever Built
Verdad Gallardo
New Electric Mercedes-AMG GT 4-Door Coupe Unveiled: 10 Things You Need to Know
Verdad Gallardo
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
Thread Starter
Junior Member
Joined: Mar 2014
Posts: 20
Likes: 0
2009 c63 amg
Thanks for all the tips guys, had the alternator tested and it failed. I just ended up buying a brand new alternator. And boy is that a fun job getting it out haha, I ended up disconnecting sway bar, radiator hoses, pulled the aux fan, coolant reservoir. My question is, since I have it apart til I get my alternator tomorrow is there anything you guys recommend I do while it is apart?
Senior Member
Joined: Jan 2012
Posts: 381
Likes: 0
From: Toronto
09 C63, 11 Cayenne S
Yes...I just did mine and while I was there, I did the water pump, thermostat, and new hoses, as well as the belt if it's showing signs of wear or any cracks. mine is also a 2009.
Banned
Joined: Jul 2013
Posts: 2,811
Likes: 7
C63 AMG
Most towns have an alternator/starter shop
They all can be rebuilt cheaply as long as the stator/rotor windings are good and the housing is ok
Bearings, brushes, bushing, VR, etc
Even coils aren't real expensive
And labor is a small portion, pretty simple
They are common amongst many marques with only a few mfgs for euro
Bosch of course, valeo among others
When buying from a dealer you may get a rebuild w/ core anyways
You can usually get them fixed for 200-400 bucks
If you can wait a few days while fixed
Sometimes they have them for exchange
They all can be rebuilt cheaply as long as the stator/rotor windings are good and the housing is ok
Bearings, brushes, bushing, VR, etc
Even coils aren't real expensive
And labor is a small portion, pretty simple
They are common amongst many marques with only a few mfgs for euro
Bosch of course, valeo among others
When buying from a dealer you may get a rebuild w/ core anyways
You can usually get them fixed for 200-400 bucks
If you can wait a few days while fixed
Sometimes they have them for exchange
Banned
Joined: Jul 2013
Posts: 2,811
Likes: 7
C63 AMG
MBWorld Fanatic!
Joined: Oct 2007
Posts: 2,311
Likes: 382
From: Texas
10 C six trizzle
checking for voltage with the car running isnt always an indication of correct alternator function. These are new age alternators they dont run full power/voltage all the time. They are lin bus controlled from the ecu. Sadly mb considers parasitic draw on the alternator a fuel consumer. So it will go through stages of weakly operating the alternator until a decel or engine breaking which it will then full field as it wont hurt fuel consumption. keep in mind that clean connections at the battery are vital.
As for bleed procedure. Fill it up, leave the cap off. start the motor. put the climate control system on full heat and defrost. Wait for the motor to warm up. rev the motor slightly until very hot air comes out the defrost vents, refill the coolant level as the air bubbles burp out. Cap it off and go drive.
As for bleed procedure. Fill it up, leave the cap off. start the motor. put the climate control system on full heat and defrost. Wait for the motor to warm up. rev the motor slightly until very hot air comes out the defrost vents, refill the coolant level as the air bubbles burp out. Cap it off and go drive.
