Updated on Reading Time: 3 minutes
Is there a squealing noise when your Mercedes-Benz engine is on? Learn how to fix the problem by replacing the serpentine belt of your Mercedes-Benz. This guide provides instructions on replacing the serpentine belt of a Mercedes V6, V8, and V12 Engines.
Repair Time:
The typical time range in hours required to complete this repair.
Repair Cost:
The average repair cost range in USD to complete this repair by either an honest mechanic or as a DIY. Including the cost of parts but not tools.
Repair Difficulty:
This indicates how difficult it is for most DIYers and mechanics to perform this repair.
Symptoms
Common symptoms of a bad serpentine belt include:
- Squealing noise when the engine is on.
- The check battery light is on.
- Insufficient AC cooling during traffic.
What will you need?
Parts
YOUCANIC Pro Manuals
Give you access to the original OEM Factory Repair Manuals. Each manual offers meticulously detailed steps and vivid illustrations, extensive wiring diagrams, precise torque specifications, and exclusive access to technical service bulletins and OEM service information—everything you need, just what the dealerships use.
Learn More
- Mercedes-Benz Serpentine Belt
Tools
- 17mm deep socket
- Socket handle
Procedure
- Park the vehicle on level ground, set the parking brakes, and allow the engine to cool down.
- Draw a layout of your serpentine belt’s original routing or, at a minimum, take a picture so that when you install the new belt, you will know how to route it.
- Insert the 17mm socket into the tensioner bolt.
- Put on the socket handle and turn counterclockwise to loosen the belt tensioner. The tensioner should move upwards.
- Slide the belt off the idle pulley on top or any pulley you find easy.
- Remove the belt from all the pulleys and discard it.
- Inspect the new serpentine belt.Position the new serpentine belt as per the drawn layout. Make sure your pulley is seated properly on all the pulleys.
- Using a 17mm socket and a handle, turn the tensioner bolt counterclockwise, as you did to release the belt.
- Slide the belt over the tensioner pulley. Slowly release the tensioner. If you cannot slide the belt over the tensioner pulley because the belt seems too short, there is a good chance that the belt is not seated properly on one of the pulleys.
- Inspect the belt position at each pulley.
- Start the engine and inspect.
Frequently Asked Question
How do you know if your serpentine belt is bad?
One of the common symptoms of a defective serpentine belt is a squealing noise when the engine is on. Since the serpentine belt drives the alternator, coolant pump, and AC compressor, you may experience low alternator output, low AC cooling efficiency, and higher engine temperature.
Can you drive a Mercedes-Benz with a bad serpentine belt?
It is not recommended to drive with a bad serpentine belt. If the serpentine belt fails, power steering will get hard, and the alternator will not charge the battery, leading to the engine dying while driving.
How much does it cost to replace a serpentine belt?
If you’re replacing the serpentine belt, the part will cost around $50-100. The labor cost would be around $ 50 – 150.
How do you know if your serpentine belt is bad?
One of the common symptoms of a defective serpentine belt is a squealing noise when the engine is on. Since the serpentine belt drives the alternator, coolant pump, and AC compressor, you may experience low alternator output, low AC cooling efficiency, and higher engine temperature.
Can you drive a Mercedes-Benz with a bad serpentine belt?
It is not recommended to drive with a bad serpentine belt. If the serpentine belt fails, power steering will get hard, and the alternator will not charge the battery leading to the engine dying while driving.
Applications
Mercedes-Benz vehicles with V6, V8, and V12 engines.
We hope you find the Mercedes-Benz ML, R, GL Class – Replace Serpentine Belt guide helpful. Check these troubleshooting and repair guides for more help on your Mercedes-Benz.
Written and fact-checked by:
YOUCANIC Techs YOUCANIC articles are written by authors who collectively have over 60 years of experience in the automotive field and years of hands-on experience on vehicles. These authors are certified ASE G1 Automotive Maintenance engine professionals (the highest level certification for vehicle maintenance and repair). They hold associate’s and bachelor’s degrees, as well as having gone on to further study to receive a master’s and doctorate degrees. These authors collaborate on research, writing, editing, and fact-checking every article to ensure that it is accurate and up to date and delivers the best counsel and information to YOUCANIC readers. View all postsRush*t Hila is an engineer and ASE certified in G1 Automotive Maintenance 
