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taroliw
Date registered: Dec 1899
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| 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... |
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bclark
Date registered: Dec 1899
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| RE: Anyone else noticed engine whine?
Lots of other issues but no whine yet.
Build date November '05.
Good luck! |
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alroumi
Date registered: Dec 1899
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Vehicle(s):
| Re: Anyone else noticed engine whine?
I have heard a whine, But I think its due to the hot weather and humidity over here; It only happened to me once while the ac is on |
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mtiede
Date registered: Dec 1899
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| RE: Anyone else noticed engine whine?
There are some people on other slk forums reporting a high pitch whine that changes with engine rpm. Fans, belts and pulleys are peoples guess, but so far nothing definitive. |
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mtiede
Date registered: Dec 1899
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| RE: Anyone else noticed engine whine?
Hah. I just noticed that car photo and taroliw. Never mind. I guess you already know about those "people" on other forums reporting this problem.  |
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taroliw
Date registered: Dec 1899
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| RE: Anyone else noticed engine whine?
mtiede - 7/14/2006 4:15 AM Hah. I just noticed that car photo and taroliw. Never mind. I guess you already know about those "people" on other forums reporting this problem. :) *snicker* Yes, I cross-posted to get widest audience. I am supposed to bring my car in this morning for a drive with a technician. One thing I noticed while paying special attention yesterday is that the sound actually isn't prominent when the engine is cold... but rather becomes noticable after about 10-15 minutes of the engine reaching "normal" temp (abt 90C). Of various suggestions I've read about whine/resonance was one that referred to issues with a thermostat and coolant flow... and I know that the tri-valve setup is rather new for this engine... things that make you go "hmm..."  So, needless to say, I'll be driving the car for at least as long before taking it to the Tech, and will be leaving the engine running whilst I wait for them to appear. No way am I going to leave the option for them not to hear it. And with the bonnet up and transmission in P I find that the resonance begins as early as 1500 RPM and by 2500 RPM it's very prominent indeed. No need to rev higher than that. Having taken a more careful listen to it, I'm eager to have a few R171's try something similar on this weekend's SLK drive... this would be a more definitive "they all do that" test, I think. :D |
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Motzkoman
Date registered: Dec 1899
Location:
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| RE: Anyone else noticed engine whine?
Bill,
We've got 21 confirmed cars tomorrow, including both 2005 and 2006 Slk 350's, so we should be able to do some good benchmarking...see you tomorrow... 
...Steve  |
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mtiede
Date registered: Dec 1899
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| RE: Anyone else noticed engine whine?
I think someone suggested the serpentine belt as a possible culprit. Does that make sense? Perhaps as it warms up in 15 minutes or so of going round and round, maybe it is stretching ever so slightly and getting loose enough to be making some squeaks? Just a thought... |
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taroliw
Date registered: Dec 1899
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| 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.
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.
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! 
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alroumi
Date registered: Dec 1899
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| Re: Anyone else noticed engine whine?
Glad its solved, Enjoy your SLK |
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