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Pelican Technical Article:

Drive Belt Replacement

Steve Vernon

Time:

1 hour1 hr

Tab:

$25 to $45

Talent:

*

Tools:

17mm socket

Applicable Models:

Mercedes-Benz C350 (2008-15)
Mercedes-Benz GLK350 (2010-15)

Parts Required:

New drive belt

Hot Tip:

Work on a cold engine

Performance Gain:

Won't leave you stranded at the side of the road

Complementary Modification:

New Tensioner

You should check your drive belt every six months for wear, cracking, fraying, delaminating and drying out. If your belt shows any of these signs you should replace it. I recommend you buy two belts and always keep an extra one in the car. You don't want to be stranded on the side of the road for the lack of a spare drive belt.

Replacing the belt on your Mercedes-Benz W204 is one of the easiest jobs you will do. You should be able to do it in less than 30 minutes. It is a great starter project if you are just beginning to DIY or "Do It Yourself" on your car.

Let the car cool so you don't have to work around a hot engine.

You will need to remove the front engine cover (red arrow) and two air ducts (yellow arrows) to replace the belt so please see our article on engine cover removal if you need additional assistance with these projects.
Figure 1

You will need to remove the front engine cover (red arrow) and two air ducts (yellow arrows) to replace the belt so please see our article on engine cover removal if you need additional assistance with these projects.

This photo illustrates the path of the belt; you can see where it passes the alternator (red arrow), power steering pump (green arrow) and A/C compressor.
Figure 2

This photo illustrates the path of the belt; you can see where it passes the alternator (red arrow), power steering pump (green arrow) and A/C compressor. Use this illustration when installing the new belt. This photo is for illustration purposes only. You do not need to remove anything other than what is described in the job.

If you look down by the thermostat you can see both sides of the belt; check the backside (yellow arrow) for any signs of cracks or fraying on the sides, on the ridged section of the belt (red arrow).
Figure 3

If you look down by the thermostat you can see both sides of the belt; check the backside (yellow arrow) for any signs of cracks or fraying on the sides, on the ridged section of the belt (red arrow). Check for cracks, separation, dryness, missing sections fraying or any cuts.

Even if your belt looks fine it can still stretch.
Figure 4

Even if your belt looks fine it can still stretch. Look carefully at the tensioner and you will see a marking on the tension side (red arrow) that needs to be between the marks on the mounted side (yellow arrows). If your tensioner is outside of these marks the belt has stretched too much and does not have proper tension on it and needs to be replaced.

There is a spud on the tensioner that takes a 17mm socket (red arrow).
Figure 5

There is a spud on the tensioner that takes a 17mm socket (red arrow).

Place a 17mm socket on the tensioner spud and turn it counter clockwise.
Figure 6

Place a 17mm socket on the tensioner spud and turn it counter clockwise. This will release the tension on the belt (red arrow) and allow you to slip it off. Use care so as not to get your fingers pinched between the belt and tensioner.

If you are worried about pinching your fingers you can lock the tensioner in the un-tensioned position by turning the 17mm socket all the way counter clockwise and then inserting a small 4mm Allen key or drill bit into the locking hole on the base of the tensioner (red arrow).
Figure 7

If you are worried about pinching your fingers you can lock the tensioner in the un-tensioned position by turning the 17mm socket all the way counter clockwise and then inserting a small 4mm Allen key or drill bit into the locking hole on the base of the tensioner (red arrow). Installation is the reverse of removal and use picture number three as a routing reference if needed.


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Comments and Suggestions:
Chris N. Comments: You can also use the factory-supplied 17mm lug wrench from the vehicle tool kit in lieu of a 17mm socket and ratchet/breaker bar. It is definitely easier with a longer ratchet or breaker bar, but it can be done with the lug wrench in a pinch.
June 6, 2017
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Dee Comments: What's the name of the small little pulling next to the tension
February 17, 2017
  Followup from the Pelican Staff: I believe that pulley is part of the tensioner. - Casey at Pelican Parts  

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Page last updated: Sun 8/20/2017 03:00:51 AM