SLK/R171: Anyone else noticed engine whine?
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Joined: Sep 2005
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From: SF Bay Area, CA
2006 SLK350
Anyone else noticed engine whine?
I don't know if I've just become hyper-sensitive to the sound, but I've noticed just lately a whine -- I'd almost think it was a supercharger, but of course the 350 doesn't have one -- related to engine RPM. Several octaves higher than the exhaust note, and much louder if I'm stationary with bonnet up (transmission in park or neutral).
I don't think it's related to high revs, because I've heard it as low as 2500. But, of course, I also tend to hear it mostly when there is something nearby for the sound to reflect back from (buildings, parked cars, etc). So it may just be that I started noticing it, but I'd also felt I should ask in case a problem is developing...
I don't think it's related to high revs, because I've heard it as low as 2500. But, of course, I also tend to hear it mostly when there is something nearby for the sound to reflect back from (buildings, parked cars, etc). So it may just be that I started noticing it, but I'd also felt I should ask in case a problem is developing...
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Joined: Jul 2006
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From: Annandale, VA
2002 C32 AMG
Hey, I am having a similar problem. I read a post on here somewhere and I think it may be the water pump! I am going to check mine as soon as I get the chance but I would look into that! Good luck! If you figure anything out, please post.
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Joined: Sep 2005
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From: SF Bay Area, CA
2006 SLK350
Will do. Just emailed my service rep that I'll want to be coming in to have it examined, and repaired as necessary. And just imagine... if I hadn't been driving a convertible I probably wouldn't have even heard the sound to begin with. 
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Joined: Jun 2002
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From: Fairhope, Al
2010 R8
I hear the same thing. I notice mine more when cold engine is first started. I also hear ticking,clicking noise like belt idler or pulley. Just got it back from dealer and tech said he did not hear anything unusual for Mercedes engine.
I think the noise from the engine compartment really makes the car sound cheap.
I think the noise from the engine compartment really makes the car sound cheap.
Thread Starter
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Joined: Sep 2005
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From: SF Bay Area, CA
2006 SLK350
That's good info. Since my commute to work is only about 20 minutes, the engine definitely has time to warm up. I do remember hearing this a little during cold starts, which didn't really worry me much. It was when I began hearing it after the engine was warm from something as simple as starting from a light. I do notice that if I go a little easier on the throttle the noise isn't as prominent. But since I tend to drive with a slightly heavier foot -- not full throttle from start, certainly, but not grandma-like 2 minutes to 35 either. -- I'm hearing it a lot.
Maybe they'll tell me it's normal, but I'd rather have it checked to be sure. After all, they'll be the ones doing any warranty repair.
-- I'm hearing it a lot.Maybe they'll tell me it's normal, but I'd rather have it checked to be sure. After all, they'll be the ones doing any warranty repair.
Thread Starter
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Joined: Sep 2005
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From: SF Bay Area, CA
2006 SLK350
Originally Posted by IERAX
A whine coming from the fuel pump situated behind the driver cabin has been reported .Could it be that?
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From: Concord, MA
2005 SLK350 Silver w/ Black; 2004 GMC Sierra 2500
I have a quite loud belt squeal when the car is first started which only occurs under 1500 RPM and only for the first 15 minutes the car is on. I have had the car to two different dealers and a total of 3 times for a fix. The fix seems to last about 2 weeks. Just made an appointment for time number 4. Apparently they keep replacing some of the pulleys but aparently not the right one yet. I agree it makes the car sound cheap, at 10K kia doesnt have belt squeeks why should a 50K benz?
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From: Canada
2015 C63S E1 (sold 2012 C63 AMG Sedan (Premium & APX)) & 09 C300 Sport 4Matic
My C made that noise, I asked the dealer to change the serpentine belt under warranty and that fixed it. They didn't want to on the first visit but on the second it happen to have a bit of a nick in it 
Thread Starter
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Joined: Sep 2005
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From: SF Bay Area, CA
2006 SLK350
Solved
OK. I brought the car in today for a technician to hear it and I totally wasn't hearing things or confusing it with something else. It turned out to be that the bearings in the upper idler pulley were beginning to fail, causing the friction and resonance I was hearing. They replaced the pulley and the noise is gone. Wonderful! And just to see how thorough the technician was -- I understand I lucked out and got a shop foreman, which always helps, here are the notes they entered into the computer to describe what work they performed.
I rather liked the touch of removing the pulleys to spin them to feel how they moved. 
But having this resolved in just one trip (and less than a day!).... priceless! 
CUSTOMER STATES THERE IS A WHINE FROM THE ENGINE STARTING ABOUT 1500 RPMS. MOVING OR STOPPED. SEE ATTACHED EMAIL.
FAULTY, NOISY IDLER BELT PULLY BEARING
RUN ENGINE. VERIFY WHINE NOISE FROM ENGINE.. RACK VEHICLE. R&R GRAVEL SHIELDS. NOISE FROM FRONT OF ENGINE. TO ACCESS, R&R RADIATOR ELECTRIC FAN. USING STETHESCOPE, LISTEN TO WATER PUMP, ALT, POWER STEERING PUMP BEARINGS. NOISE FROM ONE OF THE IDLER PULLYS. R&R POLY DRIVEBELT. SPIN PULLYS. CANNOT DETERMINE NOISE. R&R IDLER PULLYS. SPIN BY HAND. UPPER IDLER HAS SLIGHT ROUGHNESS WHILE SPINNING. REPLACE IDLER PULLY. REINSTALL BELT. START ENGINE, NOISE GONE. REINSTAL RAD FAN. ROAD TEST.
FAULTY, NOISY IDLER BELT PULLY BEARING
RUN ENGINE. VERIFY WHINE NOISE FROM ENGINE.. RACK VEHICLE. R&R GRAVEL SHIELDS. NOISE FROM FRONT OF ENGINE. TO ACCESS, R&R RADIATOR ELECTRIC FAN. USING STETHESCOPE, LISTEN TO WATER PUMP, ALT, POWER STEERING PUMP BEARINGS. NOISE FROM ONE OF THE IDLER PULLYS. R&R POLY DRIVEBELT. SPIN PULLYS. CANNOT DETERMINE NOISE. R&R IDLER PULLYS. SPIN BY HAND. UPPER IDLER HAS SLIGHT ROUGHNESS WHILE SPINNING. REPLACE IDLER PULLY. REINSTALL BELT. START ENGINE, NOISE GONE. REINSTAL RAD FAN. ROAD TEST.
But having this resolved in just one trip (and less than a day!).... priceless!
