How to Replace Alternator on Mercedes Benz R350 ML350 GL450

DIY Cost: $440-$800
Est. Time: 2 hr
Difficulty: Intermediate
This guide provides instructions on how to change the alternator on a Mercedes Benz M272 engine.


Common symptoms indicating a problem with your Mercedes Benz alternator includes:

  • The red battery light stays on
  • Dead battery

What you will need




Follow these steps to replace the alternator on Mercedes-Benz SUVs W164, X164, W251.


  1. Park the vehicle on level ground and let it cool down. If the engine is still hot, you risk getting burned. 
  2. Pull the hood release under the dashboard and open the hood.  Secure the hood with the hood support. support hood


  3. Locate the battery in the engine bay, trunk, or under the seat and disconnect the negative battery terminal. Battery Location
  4. Spray penetrating oil to the alternator retaining bolts for ease of removal.
  5. Remove the components blocking your access to the alternator, like the engine plastic cover, hoses, power steering fluid reservoir, and the overflow reservoir.Remove engine plastic coverRemove hoses


  6. Remember to take a photo or maybe draw the serpentine belts routing, so you will not have a hard time installing it back.routing


  7. Using the 14mm Wrench with the pipe as an additional handle so you will not have to exert too much force to push it counterclockwise to release the tension on the belt so you can slide the serpentine belt out.release tensioner


  8. Remove the positive terminal at the back of the alternator.
  9. Remove the connector at the back of the alternator.Remove regulator connector


  10. Remove four (4) alternator retaining bolts.RemoveAlternatorbolttop

    You may look at this figure to know how the alternator is attached to the engine.

  11.  Using both of your hands, you have to move the alternator side to side while pulling it up.Remove Alternator


  12. Remove the ground wire with the bolt.Remove ground wire and bolt


  13. Remove the alternator from the vehicle. remove alternator



  1.  Slide the new alternator back to its position and install the long bolt, and set the torque to 33 lbs. alternator


  2. Install the top bolt and bracket of the alternator and set it to 16 lbs. ft.Install Alternator Bolts


  3. Install the new serpentine belt in its original routing position and make sure that it is seated on the pully groove.routing belt


  4. Connect the connector and terminal of the alternator.
  5. Connect the battery terminal.
  6. Start the engine and check voltage. With the engine running, you should be getting between 14.0 and 14.7 volts.

Replacing the alternator on a Mercedes Benz V6 engine is relatively easy and takes about 2 hours

This procedure can also be applied to other Mercedes Benz engine's multiple models, including E-350, CLK-350, from 2006 to 2012 models V6 gasoline engines.

Also, this procedure applies to V8 engines such as S-550, E-550, CLK-550 from 2005 to 2012 models. It depends on the market because US and European models have different production years. The only difference is the space between the engine and radiator because of the additional cylinders for the V8 engines.

In eight out of ten cases the reason why the alternator is not charging is basically just because of a worn-out carbon brush that is mounted in the voltage regulator, this carbon brush is attached with a rotating mechanism that is why in time it may wear out.

If you are the one doing the DIY on your alternator and you have a tight budget sometimes you can replace just the regulator itself. It is much cheaper than replacing the whole assembly. Still, you got to make sure that the regulator is the one causing the problem.

Frequently Ask Questions 

How much does it cost to replace a Mercedes Benz Alternator? 

  • The average cost to replace a Mercedes Benz Alternator is between $447 and $800. Labor costs are estimated at around $386, while parts are priced between $350.

How long does a Mercedes Benz Alternator last?

  • The average life span of an Alternator is about six to ten years. It depends on how many miles the vehicle is regularly driven and driving conditions. 

How to test an alternator?

  • Using a voltmeter, connect your positive lead to the battery's positive terminal and negative lead to the battery's negative terminal. It would be best to get 14 v to 14.8 v, which means your alternator is working properly.

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Check out more guides for the following vehicle. , ,
How to Replace Alternator on Mercedes Benz R350 ML350 GL450 Symptoms Common symptoms indicating a problem with your Mercedes Benz alternator includes: The red battery light stays on Dead battery What you will need Parts New Alternator Tools