Mercedes-Benz C-Class: How to Replace Serpentine Belt

The serpentine belt powers every accessory on the engine. When it wears, belt slip occurs and it will decreases the A/C, power steering, and charging system performance. Continue reading to find out how to replace the serpentine belt on your Mercedes-Benz C-Class.

By Weston Chadwick - May 20, 2015
Contributors: Benzwerks,torakef

This article applies to the Mercedes-Benz C-Class w204 (2007-2014).

The alternator, A/C compressor, and power steering pump are solely powered by the rotating motion of the serpentine belt. It rides along the pulleys that are bolted or pressed onto these components. Over time, wear occurs from temperature changes and dirt entering into the engine bay. This causes the belt to stretch, crack, and eventually break. When this happens, you lose power assisted steering, air conditioning, and your charging system will no longer be operational.

Materials Needed

3/8" or 1/2' ratchet (preferably with a long handle)
T55 Torx socket
17mm socket or wrench
Small punch, cotter pin, carpenters nail etc.
Flat head screwdriver
Plastic door panel tool (optional)
Small extension (optional)

The M271 (4-cylinder) is found in the C180, C200, and C250. The C230, C300, and C350 is found with the M272 (6-cylinder) engine. Both engines will be covered, and the steps will be designated as V6 Engine (272) and I-4 Engine (271) for easy identification.

Figure 1. The M272 serpentine belt tensioner is on the left.
Figure 2. The serpentine belt tensioner on the M271. The green circle indicates the T55 slot to move the tensioner.

Step 1 – Remove engine cover and intake hoses

V6 Engine

The 272 will require you to remove the front engine cover. Simply pull forward and up to detach it. You will hear the four plastic clips on the bottom side of the cover pop free.

Figure 3. Removing the front engine cover.

Remove the dipstick. The red handle can be seen at the top of the engine.

Figure 4. Removing the dipstick.
Figure 5. Pry up on the section of the clip indicated by the arrow. This will detach the clip from the engine.

Remove both the left and right intake hoses. They pop out of place with an upward pull.

I-4 Engine

Before removing the serpentine belt, first remove the intake hose. There is one clip holding the hose to the radiator support. It must be turned 90 degrees.
There are also two clips holding the hose to the elbow. Pry these clips up to unlock them, and then pull the hose towards the front of the engine.

Figure 7. The arrows point to the clips holding the intake hose.

You will now need to loosen two hose clamps. These hold the hose running across the engine in front of the cooling fan.

Figure 8. The clamp at the right side of the hose.
Figure 9. The clamp on the left side of the hose. The screw driver points to the correct clamp.
Figure 10. The hose is being removed.

Also remove the smaller hose above the power steering pump.

Figure 11. Loosen this clamp to remove the smaller hose.

Step 2 – Remove the serpentine belt

V6 Engine

Using your 17mm socket, turn the tensioner counterclockwise to remove tension from the belt.
Insert your punch or rivet into the tensioner. This will lock the tensioner in place, and keep tension off of the belt.
Un-route the belt from the engine pulleys, and out of the engine.

Figure 12. The red circle highlights the rivet installed into the tensioner.

I-4 Engine

Once you have removed the hose, use your ratchet and your T55 Torx socket to remove the tension from the belt, and slide it off the pulleys.

Figure 13. Turning the tensioner counterclockwise to remove tension from the belt.

Step 3 – Install the new serpentine belt

Begin by routing the serpentine belt in the correct path around the pulleys. Make sure the last pulley you will be sliding the belt onto does not have raised edges; otherwise, it will be difficult to slide on.

The belt may need to be pulled with some force to make it slide onto the tensioner pulley. Install any hoses/covers you removed, and you have finished installing you new serpentine belt!