Is your Mercedes-Benz difficult to turn, has a battery warning light on the dashboard, the air conditioner stops working, or the engine overheats? Learn how to fix it by following the procedures below.
A common problem with Mercedes-Benz cars is the idler pulley (also known as Guide Pulley or Sheave Pulley), failing as early as 100,000 miles. Changing the idler pulley on a Mercedes-Benz is relatively easy for most DIYers and requires less than two hours.
Symptoms
A bad idler pulley can cause the serpentine belt to come off. Once the belt comes off, you will experience multiple problems if you continue to operate the car.
Power steering is difficult to turn.
The alternator stops working and no longer charges the battery.
Battery warning light on the dashboard
The Air Conditioner stops working.
Engine Overheats
The engine stalls once the battery is drained.
At the early stage, indicating that the idler pulley is failing, you will only hear a squeaky noise from the engine’s front. Inspect the idler pulley if you hear noise from the engine.
The noise can be described as whining. Remove the serpentine belt and check the idler pulley for play or noise by spinning it by hand.
It would be best to replace a bad idler pulley immediately to avoid future problems caused by complete idler pulley failure.
What you will need
Mercedes Idler Pulley
Thread Locker
Female Torx Set
Torx Socket Set
Ratchet Wrench
Note that the older models of Mercedes-Benz engines require a Torx Bit Socket. This is common on M112 and M113 engines from 1997 to 2007.
Newer Mercedes-Benz idler pulleys (on M272 and M273 and newer models) require a Female Torx socket. Always verify by inspecting the bolt on the center of your idler pulley.
Procedure
Park the Mercedes-Benz in an area where you can work. Changing the idler pulley on the road is possible if it fails while driving. You need to make sure you are working in a safe area.
Allow the engine to cool down for at least thirty minutes.
Pull the hood release under the dashboard on the driver’s side.
Remove the engine cover by lifting it. Locate the idler pulley at the front of the engine.
Remove the serpentine belt. Use a 17mm socket and ratchet on the tensioner nut to unload the tensioner.
Use a pin to lock the tensioner in the pre-loaded position. You can use a nail or a 5mm Allen wrench as a pin.
Slide the serpentine belt off the idler pulley. Removing the serpentine belt completely is unnecessary unless you are replacing it.
Use a flathead screwdriver to remove the dust cap on the center of the idler pulley. Do NOT discard the dust cap. It needs to be reinstalled.
Use a T-50 Torx to remove the idler pulley bolt. The bolt is long and requires patience to remove. Some models require a female Torx socket.
Install the new idler pulley and tighten the bolt to Mercedes-Benz specifications.
Install the dust cap.
Turn the idler pulley by hand to make sure it is spinning freely.
Reinstall the serpentine belt. If the belt is not long enough to slide over the tensioner pulley, ensure it sits properly in all the pulleys.
Use your 17mm socket and ratchet to move the tensioner upward to remove the locking pin.
Slowly load the tensioner.
Torque Specifications
Typical Mercedes-Benz idler pulley bolt torque:
Newton-meters 35 Nm
Foot-pounds: 25.81 ft-lb
These torque specs may vary between models. We recommend you verify the correct torque specs by calling your Mercedes-Benz dealer.
Notes
It is recommended (not required) to change the tensioner while you change the idler pulley.
If your vehicle has a viscous fan, it may need to be removed to access the idler pulley. Common on pre-2000 models.
Part Numbers
Below are part numbers for some of the most common Mercedes-Benz idler pulleys.
MODELS
PART NUMBERS
2005-10 Chrysler 300 V6 3.5L
2005-10 Chrysler 300 V6 2.7L
2004-08 Chrysler Crossfire Idler Pulley
2009-10 Dodge Challenger V6 3.5L
2006-10 Dodge Charger V6 3.5L
2006-10 Dodge Charger V6 2.7L
2005-08 Dodge Magnum V6 2.7L
2005-08 Dodge Magnum V6 3.5L
2003-06 Dodge Sprinter Van Idler Pulley
2007 Mercedes Benz C230 Idler Pulley
2001-05 Mercedes Benz C240 Idler Pulley
1998-00 Mercedes Benz C280 Idler Pulley
2001-05 Mercedes Benz C320 Idler Pulley
1998-00 Mercedes Benz C43 AMG Idler Pulley
2000-06 Mercedes Benz CL500 Idler Pulley
2001-02 Mercedes Benz CL55 AMG Idler Pulley
1998-05 Mercedes Benz CLK320 Idler Pulley
1999-02 Mercedes Benz CLK430 Idler Pulley
2003-05 Mercedes Benz CLK500 Idler Pulley
2001-05 Mercedes Benz CLK55 AMG Idler Pulley
1998-05 Mercedes Benz E320 Idler Pulley
1998-02 Mercedes Benz E430 Idler Pulley
2003-05 Mercedes Benz E500 Idler Pulley
1999-02 Mercedes Benz E55 AMG Idler Pulley
2002-05 Mercedes Benz G500 Idler Pulley
1998-03 Mercedes Benz ML320 Idler Pulley
2003-05 Mercedes Benz ML350 Idler Pulley
1999-01 Mercedes Benz ML430 Idler Pulley
2002-05 Mercedes Benz ML500 Idler Pulley
2000-03 Mercedes Benz ML55 AMG Idler Pulley
2000-06 Mercedes Benz S430 Idler Pulley
2000-06 Mercedes Benz S500 Idler Pulley
2001-06 Mercedes Benz S55 AMG Idler Pulley
1999-06 Mercedes Benz SL500 Idler Pulley
2001-04 Mercedes Benz SLK320 Idler Pulley
0002020919,
000 202 09 19 04593848AA
04792836AA 68020888AA
Engines:
M112 and M113
2008-2009 MERCEDES-BENZ C230 4MATIC SEDAN 4-DOOR
2008-2009 MERCEDES-BENZ C230 BASE SEDAN 4-DOOR
2006-2007 MERCEDES-BENZ C230 SPORT SEDAN 4-DOOR
2010-2010 MERCEDES-BENZ C250 4MATIC SEDAN 4-DOOR
2010-2010 MERCEDES-BENZ C250 BASE SEDAN 4-DOOR
2009-2010 MERCEDES-BENZ CL550 4MATIC COUPE 2-DOOR
2007-2008 MERCEDES-BENZ CL550 BASE COUPE 2-DOOR
2006-2009 MERCEDES-BENZ CLK350 BASE CONVERTIBLE 2-DOOR
2006-2009 MERCEDES-BENZ CLK350 BASE COUPE 2-DOOR
2007-2009 MERCEDES-BENZ CLK550 BASE CONVERTIBLE 2-DOOR
2007-2009 MERCEDES-BENZ CLK550 BASE COUPE 2-DOOR
2007-2010 MERCEDES-BENZ CLS550 BASE SEDAN 4-DOOR
2007-2007 MERCEDES-BENZ E280 4MATIC SEDAN 4-DOOR
2007-2007 MERCEDES-BENZ E280 BASE SEDAN 4-DOOR
2008-2009 MERCEDES-BENZ E300 4MATIC SEDAN 4-DOOR
2006-2011 MERCEDES-BENZ E350 4MATIC SEDAN 4-DOOR
2006-2009 MERCEDES-BENZ E350 4MATIC WAGON 4-DOOR
2011-2011 MERCEDES-BENZ E350 4MATIC WAGON 4-DOOR
2011-2011 MERCEDES-BENZ E350 BASE CONVERTIBLE 2-DOOR
2010-2011 MERCEDES-BENZ E350 BASE COUPE 2-DOOR
2006-2011 MERCEDES-BENZ E350 BASE SEDAN 4-DOOR
2006-2006 MERCEDES-BENZ E350 Base WAGON 4-DOOR
2011-2011 MERCEDES-BENZ E350 BLUETEC SEDAN 4-DOOR
2010-2011 MERCEDES-BENZ E350 ELEGANCE SEDAN 4-DOOR
2010-2010 MERCEDES-BENZ E350 SPORT SEDAN 4-DOOR
2007-2011 MERCEDES-BENZ E550 4MATIC SEDAN 4-DOOR
2011-2011 MERCEDES-BENZ E550 BASE CONVERTIBLE 2-DOOR
2010-2011 MERCEDES-BENZ E550 BASE COUPE 2-DOOR
2007-2011 MERCEDES-BENZ E550 BASE SEDAN 4-DOOR
2009-2011 MERCEDES-BENZ G550 BASE SPORT UTILITY 4-DOOR
2007-2011 MERCEDES-BENZ GL450 BASE SPORT UTILITY 4-DOOR
2008-2011 MERCEDES-BENZ GL550 BASE SPORT UTILITY 4-DOOR
2010-2011 MERCEDES-BENZ GLK350 4MATIC SPORT UTILITY 4-DOOR
2010-2011 MERCEDES-BENZ GLK350 BASE SPORT UTILITY 4-DOOR
2006-2011 MERCEDES-BENZ ML350 4MATIC SPORT UTILITY 4-DOOR
2009-2011 MERCEDES-BENZ ML350 BASE SPORT UTILITY 4-DOOR
2010-2011 MERCEDES-BENZ ML350 BLUETEC 4MATIC SPORT UTILITY 4-DOOR
2010-2011 MERCEDES-BENZ ML350 SPORT AMG SPORT UTILITY 4-DOOR
2008-2011 MERCEDES-BENZ ML550 BASE SPORT UTILITY 4-DOOR
2007-2011 MERCEDES-BENZ SL550 BASE CONVERTIBLE 2-DOOR
2009-2011 MERCEDES-BENZ SLK300 BASE CONVERTIBLE 2-DOOR
2005-2011 MERCEDES-BENZ SLK350 BASE CONVERTIBLE 2-DOOR
A272 202 10 19
supersede
A2722020000
2722021019
A2722021019
Engines:
M272 and M273
We hope you find the “Mercedes-Benz Idler Pulley Replacement” guide helpful. Check these troubleshooting and repair guides for more help on your Mercedes-Benz.
Rushit Hila, an ASE-certified engineer (G1 Automotive Maintenance and Repair), brings over two decades of hands-on experience in the automotive world to his writing. With a strong educational background, including a Master of Science in Engineering and a Bachelor of Science in Engineering, he has honed his skills and expertise through years of practical work. As a respected authority in the field, Mr. Hila is dedicated to offering insightful and valuable content that resonates with both vehicle owners and mechanics.
