What’s this noise? W212 E250

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clk320x

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Hi chaps,

Anyone know what this noise is on startup? It’s done it for a year or more. Only when it’s cold outside and before it’s warmed up.

The noise I’m referring to is just after the engines started.

is this the alternator over-run pulley?

(ignore the birds chirping)

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Is this it om651 engine? Sounds like pulley noise to me. Have you had any of the pulleys or tensioners changed?
Mine made a similar noise mid last year but was more continuous and only when it warmed up, but was similar. turned out be one of the idler pulleys, changed all of them bar the tensioner and it went away, oh and put a new belt on. cheap and easy job.
you can always stick a stethoscope or long metal implement onto the pulley bolts while the engine is running, (obviously be careful) and stick it to your ear, if its failing pulley the noise will be quite loud.
 
Is this it om651 engine? Sounds like pulley noise to me. Have you had any of the pulleys or tensioners changed?
Mine made a similar noise mid last year but was more continuous and only when it warmed up, but was similar. turned out be one of the idler pulleys, changed all of them bar the tensioner and it went away, oh and put a new belt on. cheap and easy job.
you can always stick a stethoscope or long metal implement onto the pulley bolts while the engine is running, (obviously be careful) and stick it to your ear, if its failing pulley the noise will be quite loud.
Yeah it’s a 651 - have had the belt tensioner changed as well as the serpentine belt.

I’m thinking it’s the alternator idler pulley but I have no idea tbh 😂 by the time it gets to the garage it’s warm and silent 🤣
 
Price on Alternator pulley from MB is nearly £170 so need to make sure it’s 100% the culprit before buying it
 
Barely hear anything, is it worth spending £££ on a slight noise?

If really concerned get someone to take a look at it, no point speculating over such a tiny sound :)
 
Can’t hear anything, but the video is very short.
 
I’ll get another vid tomorrow chaps thanks
 
I don't have your VIN to do an exact part number check through 7zap and check Autodoc, but 7zap lists 4 Valeo alternator part options (some being reconditioned).

Taking first non-reconditioned alternator part number in 7zap is A0009067900.

Then (Brexit issues aside and just for competitive indicative part price comparison) Autodoc lists:

Valeo part 440328 remanufactured for £225

Valeo part 200240 new for £247

14v 180A rating both with 50.86mm diameter belt pulley, 6 ribs.

I don't know which alternator you need, but if you did go down this route and could get a full reman alternator for another £50 (including regulator) then I'd look at that.

After following the advice to get it checked to make sure you need to spend the cash 👍
 
If the pulley is faulty it’ll be seized.
You can tell this by taking the belt off and trying to jolt turn the pulley clockwise, it should sort of freewheel if it doesn’t then it’s faulty.
Any garage should find that regardless of it making the noise at the time of testing or not.
The pulleys are available from euro car parts.
 
I think its also possible to get a metal probe onto the alternator pulley with some car to have a listen when its running, I did on mine when I was diagnosing the worn idlers.

Although the sounds isnt to bad I would be tempted to leave it for a while and see if it gets worse, eventually it should become obvious, or it may well just stay that way? As you mentioned its a lot of money
Or you could always get this? New Genuine Febi Bilstein Alternator Freewheel Clutch Pulley 33473 Top German Qu 4027816334736 | eBay
 
Although the sounds isnt to bad I would be tempted to leave it for a while and see if it gets worse, eventually it should become obvious, or it may well just stay that way? As you mentioned its a lot of money
Yeah it’s been like that for around a year I think. I just don’t want it to totally fail and me be stranded somewhere hence worrying - but fingers crossed it’ll be ok
 
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532010810​

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535016810 / Alternator clutch pulley​

Hope the above helps, without knowing your reg im guessing om651 around 2011/12 non of those anywhere near £170
 
One advantage on the OM651 is the timing gear is at the rear of the engine whereas the alternator drive is at the front which may help tracking noise location?
 
To conclude;

Alternator Freewheeling Clutch...

OEM part is INA branded and £180 from Newcastle Merc
INA Branded direct from motor factors £17.50 😂

Job done - you can probably guess which one I bought ;)
 
To conclude;

Alternator Freewheeling Clutch...

OEM part is INA branded and £180 from Newcastle Merc
INA Branded direct from motor factors £17.50 😂

Job done - you can probably guess which one I bought ;)
Can you please share the part no (ina).
 
My happiness was short lived, it’s back and even louder that before. Only on cold start for a few seconds, see below:
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maybe the idler pulleys?
 

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