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2001 C320
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81 Posts
Discussion Starter · #1 ·
From a tech article it sounds simple enough, however the engine bay is pretty cramped on the C320, will I have to remove anything else to be able to replace the pulley or is it just a bit of a squeeze?

And are do the new pulleys require different tools to the original ones? It hasn't been changed since new.
 

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Coupe/Convertible Forums Moderator
CURRENT: 2011 SL550 FORMER: C300, ML350, CLK550 Cabriolet, C240, ML320, 300TD
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Huh? There's almost enough room to crawl in the engine bay with the M112 engine in a W203 chassis! The idler pulley could not be easier to replace. The pulley is held on its bracket with a single Torx bolt. Just remove the serpentine belt, remove the bolt, swap in the new pulley, replace the bolt and belt. Done!
 

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2001 C240, 1984 300D
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951 Posts
Yeah, I did mine last year and it really is that simple. The only caution is that the bolt is threading into some fairly soft alloy and it would be easy to strip the threads if you overtorque it. Check the torque spec - it's surprisingly low - and be sure to use a torque wrench.

And if you have the old style tensioner you might consider replacing it at the same time.
 

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^+1. Actually, I seem to recall having a hard time finding the proper torque for the bolt before doing the job, so I did a trial-and-error on it before removal and it was something like 9Nm.
 

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99' E320, 00' E320, 03' E320T, 05' C230K
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5,025 Posts
Just changed the idler and tensioner pulley on my CLK 320 not too long ago. As mentioned, piece of cake :smile

My notes shows 25Nm (18.4 ft/lb) for tensioner bolts and 20Nm (14.77 ft/lb) for idler.
 

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2005 CLK55 AMG Coupe ,CLK320,Former,C180 Kompressor,Jensen Healey,Ford Capri V6,Alfa GTV.
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I fitted a new idler pulley about two months ago.
As Rodney says,there is no clear answer as to the correct torque for the bolt. The bolt is a T50 torx and I ended up torqueing it to 15 Nm.
You need a 17mm socket on a breaker bar to release the tension,actually there is no need to completely remove the belt.
Easy access,easy job,should take about 5 minutes. Use a screwdriver to remove the plastic cap on the front of the pulley.It just clips/pushes back on.
 

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99' E320, 00' E320, 03' E320T, 05' C230K
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You need a 17mm socket on a breaker bar to release the tension,actually there is no need to completely remove the belt.
Older pulleys with the male torx screw in the middle of the pulley will require a E10 Torx socket.
 

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2001 C320
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81 Posts
Discussion Starter · #9 ·
Finally found some time to do it...and I can't believe I didn't find out earlier but my tensioner seems to require something that looks like this to remove.






The thing is, it looks like the old style tensioner but it doesn't have the thing you need an E10 torx socket for...
 

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2001 C320
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Discussion Starter · #10 ·
Finally found some time to do it...and I can't believe I didn't find out earlier but my tensioner seems to require something that looks like this to turn.

The thing is, the pulley itself (the black plastic wheel) looks like the old style tensioner but it's secured by the thing you see on the new style tensioner:
 

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2001 C240, 1984 300D
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951 Posts
Yes, if you have the old style tensioner you'll need an E10 torx socket to release the tension. Since the old style tensioner was also somewhat prone to failing replacing it with the new style makes sense while you have the belt off. At about 100k I changed my belt, tensioner and idler pulley just so I don't need to worry about it for the next 100k. My idler pulley was cracked and looked like it was ready for imminent failure.
 

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My advice - don't replace just the tensioner pulley, but instead replace the entire tensioner assembly. The spring mechanism also wears and can create noise. Mine would make a "clucking" noise when the steering was turned full lock.
 

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'01-E320 & 02-ST2
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Plus one to Rodney's advice.

Although, OP, it sounds to me like you have the newer-style tensioner. There's no way to put that pulley on the old design, so if you have that design, you use that big 17mm casting to rotate the tensioner (with the pulley) so you can R&R the belt.

Megadamp, I think your user handle explains why your bolt looks like that. :(

Good luck, all.
 
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