Mercedes-Benz Alternator Replacement | V6 & V8 Gasoline Engine

Is your Mercedes-Benz battery dead, or the red battery light stays on due to a faulty alternator? Learn how to fix the problem by replacing the alternator of your vehicle.

This guide provides instructions on changing the alternator on a Mercedes Benz M272 engine. This procedure also applies to the V8 M273 engine, which uses a similar alternator.

Symptoms

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

• The red battery light stays on
• Dead battery

What you will need

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Parts

• New Alternator

Tools

• 13mm socket
• 17mm socket
• E-12 Torx socket
• 10mm automatic combination wrench
• Flat screwdriver

Procedure

Follow these steps to replace the alternator on Mercedes-Benz SUVs W164, X164, and W251. This engine set is also found on several sedans, such as the E350 and CLK350.

Removal

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. 
3. Locate the battery in the engine bay, trunk, or under the seat and disconnect the negative battery terminal. 
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 overflow reservoir.
6. Remember to take a photo or draw the serpentine belt routing, so you will not have difficulty installing it back.
7. Use 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.
8. Remove the positive terminal at the back of the alternator.
9. Remove the connector at the back of the alternator.
10. Remove four (4) alternator retaining bolts.You may look at this figure to know how the alternator is attached to the engine.
11.  Using both hands, you must move the alternator side to side while pulling it up.
12. Remove the ground wire with the bolt.
13. Remove the alternator from the vehicle. 

Installation

1.  Slide the new alternator back to its position, install the long bolt, and set the torque to 33 lbs. ft.
2. Install the top bolt and bracket of the alternator and set it to 16 lbs. ft.
3. Install the new serpentine belt in its original routing position and ensure it is seated on the pully groove.
4. Connect the connector and terminal of the alternator.
5. Connect the battery terminal.
6. Start the engine and check the voltage. You should be getting between 14.0 and 14.7 volts with the engine running.

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, and CLK-350, from 2006 to 2012 models V6 gasoline engines.

Also, this procedure applies to V8 engines such as S-550, E-550, and 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 alternator is not charging because of a worn-out carbon brush that is mounted in the voltage regulator; this carbon brush is attached to a rotating mechanism which is why it may wear out.

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

We hope you find the Mercedes-Benz Alternator Replacement | V6 & V8 Gasoline Engine guide helpful. Check these troubleshooting and repair guides for more help on your Mercedes-Benz.