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Discussion Starter #1
Hey all. I’d appreciate it if you could take a sec and listen under the hood of my 2005 SL55 AMG with 63,000 miles. Note: this is after the engine is warm and is not at cold startup.


To me, it sounds like a bearing of some sort down low on the passenger’s side of the engine. In the 4 years/15,000 miles I have owned the car, that sound has always been there. I am the second owner, and the previous owner always had it serviced at the Mercedes dealer for every little thing. When I visit an independent shop or local Mercedes service center, not one service writer or mechanic has ever mentioned it ... so I assume it’s normal?

Since I've owned the car, I/or a shop have replaced the following parts that might relate in some manner:
  • All belts, tensioners and idler pulleys
  • Alternator
  • ABC pump and reservoir
  • Supercharger pulley bearing (Nachi Heavy Duty Bearing 45BG07S5A1G-2DL)
Even though I have heard this sound on other YouTube videos, it doesn’t sound right to me. It’s as though something is failing so any input would be much appreciated!

Thanks,
Bob
 

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2003 sl55amg
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Mine has 82K miles and doesn't make that sound. Try using a long screwdriver in various spots with the end touching your ear to locate it. The A/C clutch may be noisy comes to mind.
 

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Discussion Starter #3
cbr1000dude: Thanks for the reply. I tried the long screwdriver on the supercharger -- not a match -- but I was reluctant to get that driver down deep on that running engine. Not much room for error with all those moving belts and pulleys. If I can find a long wood dowel I will give it a try soon.
 

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I made a short movie of mine running with the ac off, but it won't post for some reason. You might try pushing the ac off button and see if it changes.
 

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Discussion Starter #5
cbr1000dude: Thanks. I will try that AC off tip, but I believe it was there regardless. I will confirm though.
About that video, perhaps you have it set to private viewing only?
 

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Discussion Starter #8
I tried the AC off, but no change. After probing around with a stethoscope I'm pretty sure that it's the air conditioning unit making the noise so, even though it's been like this for as long as I've owned it, I may as well find a shop to do the work and put in a remanufactured unit. I don't feel like taking that front end of the car off myself.
 

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2003 SL55; 2011 E350 BTC
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I'd take the belt off and spin all the pulleys and bits to check for loose or rough bearings. It's a quick lever on the tensioner with a breaker bar and I believe 15mm deep socket to pull the belt. You may find a few items that need attention, and you can replace the belt and keep your original for backup. Every used MB I have purchased needed a pulley or 2.
 
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