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Premium Member 1999 SLK 5.4 M113
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Discussion Starter #1
i havent had the car long.. so im not sure if this has been happening for a while. in the mornings, for about half a minute or so, theres a humming, or deep whistle that comes from the intake right next to the passenger headlamp.

my guess is it has something to do with the supercharger... anyone heard of this??
 

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Administrator 2009 SLK 55 AMG/Founding Member 2006
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known issue on the 230. do a search top right if you haven't for some hits on this subject
 

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Maybe I have the same

Just wondered if you found what the problem was? I've tried a serch but I can't come up with an answer. Interested in the common problem. Thanks
 

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Thank you, seems like I may have a different problem.

High pitched whine which rises with engine revs but does not affect performance. It was diagnosed as rear bearings in the supercharger so I replaced that with a low mileage SC but the same sound persists.
No engine light as a clue because I've just noticed that even before cranking the starter, there's no light showing and I can't remember if the light has shown previously. I've had the car 4 months and it's been really great and runs very well, I'm hoping it's a bulb failure and not something more sinister. The last owner had the car for 6 months but the owner before that had it for 8 years and up to that point had a full and detailed history. I'm hoping to have the codes read at a MB Indy tomorrow.

Thanks for reading this - any thoughts?
 

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Thanks

I'll try to video over the holidays. I also wondered if it could be an alternator bearing, I thought I might try removing the front belt and then try to fix up a makeshift belt to run just the supercharger, if the noise is gone then I would suspect the alternator. I've tried swapping the deflection and tensioner pulleys for known good ones. Any thoughts on what could be used as a makeshift belt - it onlt needs to run for a few seconds at idle speed?
 

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Thanks, yes I've used a stethoscope but there's a alloy bracket which holds the supercharger, the alternator and the tensioner which is acting like an amplifier or transmitter so the sound is pretty much the same wherever you press the probe. Looks like I'll need to take the front belt off first then see if we still have the noise. Thanks to all who have tried to help, it really lifts the spirit.
 

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Fingers Crossed!

Just an update. Today I removed the front belt completely and there was no noise, great! So, I then got lucky with an old v belt that was lying around the garage that, with a bit of a stretch, managed to fit around the crank and alternator pulleys, I then ran the engine and the noise was back. It's got to be the alternator. I've ordered a new one which will be in stock tomorrow lunchtime and fitted shortly after. I hope this is the fix, I'll confirm after the festivities.

I must apologise to Turdo2 for taking over his post and also thank everyone who's tried to help with this problem.

A happy and trouble free new year to you all.
 

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Update

I fitted the new alternator yesterday and the whine has gone which is a great relief. The old alternator showed no signs of bearing failure but I didn't spend much time examining it.

A twist in the tale was when I wired up the new alternator then reconnected the battery, at position 2 the dash lights all just flashed on then immediately off again, I couldn't get steady lights at key position 2 but the car would start and all electrics worked as they should. I disconnected the battery again then disconnected the alternator cables then reconnected the alternator then the battery then everything was fine and the dash warning lights worked as normal. Again great relief but very odd.

I'm hoping that that's job done and others might benefit from my findings. I'll hang on to my spare supercharger for the time being just in case...

Bye for now.
 

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Premium Member 1999 SLK 5.4 M113
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Discussion Starter #13
no need to apologize Fab2000, it seems youve found a solution!

question: did everyones whine seem to go away once the engine was warm? my noise sounds as though its a drone coming through the intake passage at the top of the radiator, about a minute after the car has dropped its idle down to ~800 from a cold start, the noise just STOPS. i should make a video
 

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Premium Member 1999 SLK 5.4 M113
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Discussion Starter #14
note: this IS NOT a HVAC issue, this is coming from the very front of the car. its more like a blowing noise untill you get in the ~2000 rpm range then it really starts humming.

i had an issue like this on my 98 contour SVT.. it was just an intake drone from the short intake.
 
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