How to replace the alternator on a Mercedes Benz.
Step by step instructions on how to replace the alternator on a Mercedes Benz
- Open the hood.
- Disconnect the NEGATIVE terminal from the battery. HINTS: Locating the battery. Depending if you have a C / E / CLK class it could be either in the engine bay compartment, under the rear seats, or in the trunk. In our case we are working on a C Class W203 2001-2007 and the battery is located in the engine bay. First we need to remove the cabin air filter housing. Push up the 3 clips shown in the picture below and pull out the housing.
- Remove the bolt on the NEGATIVE battery terminal clamp and disconnect the cable. You will need to loosen the 10 mm bolt, no need to completely remove the bolt.
- Remove the engine cover. It comes right up. It’s has clips that hold it in place and no screws.
- Remove serpentine belt. Read this article and watch the video on how to replace the serpentine belt.
- Remove the cap from the back of the alternator. This is the electrical cable which is part of Circuit 30. Alternator is identified as G2 on electrical schematics.
- You should see a nut. Remove the 13mm nut on the back of the alternator. See the close up picture below.
- Unplug the connector that goes into the back of the alternator. Pres on the tab and pull it away from the alternator.
- Remove the two bolts that hold the alternator in place using the Female E Torx sockets we listed on the required tools section above.
- Remove the alternator. It won’t be easy to remove it but you can do it. You may have to use some force in this process. This step won’t be fun.
- Install the new alternator. Here are a couple of pictures of our new alternator which we bought for $115 on Amazon. If you need to find a replacement alternator at a fraction of dealer prices and even cheaper than your local parts store check Amazon, click here.
- Install the new alternator and tighten the two bolts to 42 Nm.
- Connect the electrical cable to the alternator. Tighten the nut for the electrical cable ( positive +) between 15-18Nm.
- Plug the electrical cable on the back of alternator and make sure it clicks when you push it in. That way you know it is locked in place.
- Reinstall the serpentine belt, the engine cover and the reconnect the battery.
- 2 Bolts that hold the alternator in place. Max 45 Nm.
- 1 Bolt on the back of the alternator. Between 15 Nm to 18 Nm.
How much does a Mercedes Benz alternator replacement cost?
The answer depends on where you live. With that in mind we will give you a general idea. First is the price of the alteratnor. If you buy it at the dealer you can will end up spending around $1000 to replace the alterantor. If you do it yourself you will can save hundreds and replace the alternator for 1/10 of that. How?
C Class Models: C240 C320 C32 C280
CLK Class: CLK320 CLK430 CLK55
Related Part Numbers
Bosch Alternator 12 120 Pulley Rotation Polarity
Bosch 0124515046, 0986042550, 0124515132
Chrysler 5097755AA, 5097756AA
Mercedes 0111546802, 011-154-72-02
Mercedes A011-154-68-02, A011-154-72-02
Valeo 2542317, 437222, 542317, SG12B021
Bosch 0-124-515-056, 0-124-515-132, 0-986-047-540
Please use the comments section below to let us know how your job went. Feel free to post any recommendations or suggestions to help others.