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Discussion Starter #1
Hi all,

I recently bought a 2003 w220 S600 V12 Bi Turbo and note when the engine is cold started it is whisper silent. Not a noise at all just V12 lust.

When the motor gets fully up to temp and idles for a time there is a knocking / rattling noise coming somewhere from the front of the motor. It does not appear valve trian related more like the serpentine belt area perhaps.

Has anyone had a pully fail in such a way that its quiet when cold and makes a racket when hot?
 

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Those pulleys can be quiet when cold and noisy when hot, or the other way around. My mechanic has a stethoscope with a stick and he touches it near the various pulleys and you can hear the noise inside. Somewhat dangerous as it could get stuck in the belt and pulled out of your hands. You can also feel around for looseness at the various pulleys when it's not running. My alternator made noise when I first got my W220 and when I was having motor mounts replaced my indie straightened it out.
 

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If it is, in fact, a pulley, I would do all of them, the two idlers and the tensioner, along with a new belt.

That belt is a PITA.

You have to pull the radiator fan, which requires disconnecting the transmission cooler line and removing the upper coolant hose, which, in turn, requires draining the coolant.

Best to do all the components at once, since you don’t know their age, so that you’re only diving into this once.
 

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Hi,

I too use the "Stethoscope" method, it is only dangerous if you do not pay attention to and think about what you are actually doing :p

I would also check the other ancilliaries like Water Pump etc too, did one recently with the pump rattling away merrily 😉

HTH,
 

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That belt is a PITA.
You have to pull the radiator fan, which requires disconnecting the transmission cooler line and removing the upper coolant hose, which, in turn, requires draining the coolant.
It's just about possible to get the belt in and out with the fan in place.

It's also possible to get the fan in and out without touching the coolant hoses, but it takes a bit of force.

This was my black TT by the way. I've been in touch with JC quite a bit already and it seems to be in better hands than last year. It was a nice car to drive, and a lot less trouble than my silver car.

Nick
 

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Discussion Starter #6
Gents - thank you all for the replies. It is good to hear some pulleys may not make noise cold and can make noise when hot. These engine bays are ovens too so they are dealing with pretty extreme temps.

I will go ahead and order all idler pulleys and the tensioner from my delaer. The fan belt is already new on the car. I'll then pull the cooling fan, fit these parts (Since they likely need done anyway!) and see how it is after that. Good time for fresh coolant also.
 

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Discussion Starter #7
Finally got to this job and the 3x pulleys do feel / sound bad. So I think when all buttoned up the noise should hopefully be gone. I'll report back when it's running again In a week or two. This video shows how they sound. The tensioner pulley feels OK


And here are the INA replacements who are a OE supplier to MB and no chineseum here :)

20191010_190604.jpg
 

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Yeah, those pulleys sound like they're about due. The tensioner pulley, though, doesn't look or sound so bad, according to the video.

INA is exactly the way to go for these pulleys. Well done.
 

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Just look at the quality of those INA compared to a lot of the sh1t that is about these days, even get new Caps :)
 

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Discussion Starter #10
Just look at the quality of those INA compared to a lot of the sh1t that is about these days, even get new Caps :)
I did remove the old pulleys last night to free up more space for the other work planned. The markings on the original bearings are IDENTICAL to the INA parts. So these are the OE parts no question :D
 

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I used INA when I did this job a while back.

Good quality parts.

I use INA for timing and serpentine belt components on my Volvos, too. I suspect they’re the OEM for many European manufacturer.
 
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