This guide provides step-by-step instructions with pictures on how to change the Mercedes-Benz serpentine belt on V6, V8, and V12 engines.
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The instructions on how to change the Mercedes serpentine belt (also known as Drive Belt, Poly V Belt) apply to all Mercedes-Benz cars with six and eight-cylinder gasoline engines such as M112, M13, M272, M273, etc.
Changing Mercedes-Benz serpentine is an easy task and requires about thirty minutes.
Symptoms that you need to change your Mercedes-Benz serpentine belt include squealing noise (most noticeable at startup). The serpentine belt may show signs of cracks damaged ribs.
Other possible symptoms include powering steering noise, poor air conditioner, and battery warning light.
Do not ignore your serpentine belt if it shows signs of damage. If the belt comes off when the engine is running, it can cause unnecessary damage to engine components.
Order the correct Mercedes-Benz serpentine belt for your car. The belt can be purchased online or at any auto parts store or dealer.
Park the car and allow the engine to cool down.
Open the hood by pulling the release under the dashboard on the driver's side.
Locate the serpentine belt at the front of the engine.
Place a 17mm socket and ratchet on the tensioner and move the tensioner UP. Turn the wrench counter-clockwise.Some models have a Hex bolt in the pulley center that can be used to release the drive belt. Do NOT use the secure TORX bolt to release the tensioner. Use the 17mm nut below the pulley.
Insert a pin (such as a 6mm Allen wrench) into the locking hole. The tensioner needs to be all the way up to be able to insert the locking pin.Make sure that the pin is strong enough and is inserted properly.If the pin is not inserted in the proper hole or is not inserted fully, it can snap off and cause damage or body injuries.
Remove the old belt by sliding the belt away from all the pulleys.
Install the new belt. Route it over the powering steering pump, A/C compressor, crankshaft, alternator, idler pulley. It is important to take a picture of the old belt before removing it and using it as a reference.Otherwise, you will be wondering how to route the belt. The serpentine belt routing is printed on top of the upper radiator support or under the hood on some cars.
Next, slide the serpentine belt over the tensioner pulley.
Check that the belt is seated properly on all the pulleys. If the belt is not seated properly, it won't be easy to slide over the tensioner, even on one pulley.
Use the 17mm to lift the tensioner and then remove the pin.
Slowly lower the tensioner and allow it to load on the belt.
No parts need to be removed to remove and replace the Mercedes serpentine belt.
Removing the engine cover by pulling it up can make this job easier, but it is unnecessary.
The radiator cooling fan does not need to be removed.
A pin can be used to lock the tensioner in the UP (preloaded) position.
It is possible to change the belt without using a locking pin.
Take a picture of the belt routing before you remove the belt.
Do not use the Secure Torx bolt to release the tensioner.
If you have a turbo intake pipe, remove it to access the tensioner.
The original belt can potentially last up to 100k miles. We recommend changing it every 60,000 miles.
It costs less than $50 to change the Mercedes-Benz serpentine belt yourself. The average cost to change the dealer or mechanic belt ranges between $100 and $250 for labor and parts.
Mercedes-Benz Serpentine Belt Diagram
Typical routing of Mercedes Benz serpentine belt. Whenever possible, take a picture of the old belt routing before removal. The drive belt routing diagram may be printed underneath the hood or top of the radiator support.
Instructions on how to change the Mercedes-Benz drive belt apply to the following models. These instructions may apply to other models not included in this list.
I have been working on vehicles for over 20 years. In 2016, I decided to start YOUCANIC so that I can empower vehicle owners all over the world. Currently, I hold an ASE certification on G1 Automotive Maintenance and Light Repair.