Transmission whine is it normal or not
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W205 C300
Transmission whine is it normal or not
Just wondering if anyone else's C300 makes the same noise as mine. When decelerating in gear from a high RPM to a lower RPM the car makes a loud noise between 3000 to 2000 RPM. Sounds like a propeller plane almost, its a really annoying whine. Only happens when I'm off the gas and slowing down. For example, if I'm coming to a stop and use the paddles to downshift and engine brake I'll hear the noise. Same thing if I'm doing some sporty backwoods driving and slowing down for curves. Can't really hear it in Comfort mode since the RPMs don't get that high but its really prominent in Sport+ and Full Manual. Also, it kind of sounds like its coming from the rear so it might be the diff, but could very well be the tranny 
. What your thoughts/experience regarding the the tranny/diff?
. What your thoughts/experience regarding the the tranny/diff?
Last edited by vic300; Feb 20, 2015 at 07:15 PM.
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Joined: Jun 2008
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From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
If it's diff noise it's very easy to check with everything off in the car ~ sound etc. Play the throttle gently from on to trailing throttle & the noise will come & go. Sign of pinion bearing having lost preload.
What you describe however sounds like the turbo controller dumping uneeded boost.
What you describe however sounds like the turbo controller dumping uneeded boost.
Thread Starter
Newbie
Joined: Sep 2014
Posts: 6
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W205 C300
Hmmm makes sense if it's the turbo controller. I wouldn't expect Jinzen and his loaner to be defective then too. This is my first turbo car so still getting used to the engine. That must be a lot of excess boost though cuz the noise is pretty significant.
