Does your Mercedes-Benz difficult to start, has a loose engine belt, and you hear screeching noises? The problem may be a worn belt tensioner.
Replacing the belt tensioner on a Mercedes-Benz is easy and takes about one hour. Follow the video and steps below to learn how to replace a Mercedes-Benz serpentine belt tensioner.
What will you need
- Mercedes-Benz Belt Tensioner
- 17mm socket
- Female Torx Socket Set
- (E10 or E12)
- Ratchet Wrench
- 2″ Ratchet Extension
- Metal Pin
- Use a nail or 5mm Allen key
- Mercedes Serpentine Drive Belt
- While it is not required to replace the drive belt, it makes sense to replace it simultaneously as the tensioner. It is ok to reuse the old belt if it does not show wear, cracking, degradation, or drying.
- Park, the Mercedes-Benz, set the parking brakes and allow the engine to cool down.
- Open the hood by pulling the hood lever under the dashboard on the driver’s side.
- Use a 17mm socket to move the tensioner up (service) position.
- Insert a metal pin in the tensioner hole to keep the tensioner up. A 5mm Allen wrench or bolt can be used as a pin. The pin needs to be strong enough to withhold shear force. Do not use any item made of plastic as a pin.
- Slide the drive v poly belt away from the tensioner.
- Remove the top Torx bolt using an E12 Torx socket and a 2″ extension.
- Remove the lower Torx bolt.
- Some models also have a shock attached to the tensioner. Remove the upper bolt from the shock to disconnect it from the engine block.
- Install the new timing belt tensioner. Start threading the tensioner bolts by hand until a few threads have gone in.
- Torque the tensioner bolts to the recommended manufacturer specifications. Typical torque for the tensioner bolts ranges between 25Nm to 35 Nm. Check with your dealer.
- Install the drive belt. Make sure it is routed on all the pulleys properly. If the belt does not reach, ensure it is not sitting on top of one of the pulleys.
- Put pressure on the tensioner’s 17mm head to move the tensioner up and remove the locking pin.
- Start the engine and ensure the belt and tensioner are working properly.
Over time the tensioner pulley can start to crack. If not replaced on time, it can fail while the engine is running. The drive belt will come off the various pulleys, possibly causing damage. The tensioner pulley bearing may also fail. When this happens, you normally hear noise from the front of the engine.
Replacing the drive belt tensioner on the Mercedes-Benz engine is relatively easy. It requires a few basic tools and approximately thirty minutes.
This guide applies to the majority of Mercedes-Benz cars. The procedure is the same for many engines, including M112, M113, and M273.
The average price to change the belt tensioner at the dealer ranges from $400-$650. Local repair shops will charge between $280-$450. The DIY cost to change the Mercedes-Benz drive belt tensioner ranges between $50-$120, even if you have to buy the tools needed for this job and a new serpentine belt.
|Interchange Part Numbers||
|Interchange Part Numbers|
(272 200 02 70)
We hope you find the Mercedes-Benz Belt Tensioner Replacement Guide helpful. Check these troubleshooting and repair guides for more help on your Mercedes-Benz.
Thank you for the instruction and it help me replaced my 2010 GLK350 idler puley, belt and tensioner as my car had chirping sound from the hood. Though I have a question, I noticed that tensioner on the mount side have two markers as well as one marker on the tensioner side, I saw some video said that the marker on tensioner side should falls between that two markers on the mount side, but mine doesn’t it’s a little bit on left side wider marker and it’s almost the same position before I replaced belt and tensioner (that was the reason I was thinking I should replace the belt and tensioner). Please let me know if this is normal or some other things I need to check out.
Thanks in advance.