SL55/63/65/R230 AMG: Have some sort of rattling sound (from belt?) at front of engine (video inside)...
http://www.youtube.com/watch?v=bLZOI...ature=youtu.be
Supposedly, it has to be replaced at 50K for most Mercedes.....I replaced mione and the noise I was having disappeared.......
I'm not sure if they replaced it when they did the belt....
I don't think some mechanics realize that it has to be replaced at that interval. Look in your service manual and see when it is recommended.
I had to ask my shop to replace it.... They were not pro-active ...... It costs about $100 for the part...I had them do it with the belt change.... Hope that helps...
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I had a mechanic look at it today with a stethoscope and he said most of the noise is coming from that one on the very left. He said it was an idler roller....
However, is the idler roller AKA idler pulley? Or are those 2 different parts? Is this different than the serpentine pulley?

I had a mechanic look at it today with a stethoscope and he said most of the noise is coming from that one on the very left. He said it was an idler roller....
However, is the idler roller AKA idler pulley? Or are those 2 different parts? Is this different than the serpentine pulley?
Keep the ol;d belts and recycle the cheap plastic pulleys UNLESS they aren't noisy. Put them in your spare box along with the old belts in the trunk as insurance if you get stranded....
Last edited by grane; Oct 20, 2012 at 09:26 PM.
The dealer wanted about $ 650.00 for the job with parts. I am 100% this is what your hearing. The plastic inner pulley inner bearing is shot and the noise will get real loud when it just explodes like mine did. You will be so surprised how quiet your engine will be after this simple repair.





