C350 humming/exhaust note above 60mph
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C204 C350 12
C350 humming/exhaust note above 60mph
Hi everyone I have a 2011 204 c350 V6 petrol/gas just noticed on the motorway that I can hear what sounds like exhaust note at a monotone hum when I get above 60mph. Everything looks fine in the engine bay, fluids are all topped up, temps are fine and tyres seem ok and are at the correct psi anyone had this issue before ? It almost sounds like it's coming from the stero center dash like it's being played as music.! Cheers thanks.
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Mercedes SL R231
Is the car new to you? Could it be weather related? I have a similar noise being caused by my blower motor. I only notice it when it is cold outside. I have a new motor but haven’t gotten around to replacing it.
It is really hard to locate the source of a noise when driving, but if it is exhaust related, I would think the noise would be coming from the rear.
It is really hard to locate the source of a noise when driving, but if it is exhaust related, I would think the noise would be coming from the rear.
Last edited by GTIBlack; Nov 30, 2025 at 12:49 PM.
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C204 C350 12
Is the car new to you? Could it be weather related? I have a similar noise being caused by my blower motor. I only notice it when it is cold outside. I have a new motors but haven’t gotten around to replacing it.
It is really hard to locate the source of a noise when driving, but if it is exhaust related, I would think the noise would be coming from the rear.
It is really hard to locate the source of a noise when driving, but if it is exhaust related, I would think the noise would be coming from the rear.
I will give it a go with the air off see if that shuts it up.
Thanks for your reply. I appreciate it.
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Mercedes SL R231
Is the radio on or off when this happens? You may want to turn COMAND all the way off and see if you hear the noise.
Removing the cat but leaving the rest of the exhaust in place should not make a big difference in sound.
Removing the cat but leaving the rest of the exhaust in place should not make a big difference in sound.
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C204 C350 12
what will shock you is how many V8 and twin turbo AMGs I own. I think I'm being overly sensitive or wasn't expecting the engine to bark like it does.
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c3500 4matic
I had an ‘09 C350 4matic Fully stock, including exhaust. It had a nice slightly aggressive growl when accelerating moderately to hard. And was pretty quietest at highway cruising.
I moved on to a 2013 C350 4matic, also fully stock. It had a less aggressive growl when accelerating, at when highway cruising the exhaust note was a slight but noticeable drone, not like the ‘09. It’s not unpleasant, just different.
I moved on to a 2013 C350 4matic, also fully stock. It had a less aggressive growl when accelerating, at when highway cruising the exhaust note was a slight but noticeable drone, not like the ‘09. It’s not unpleasant, just different.
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C204 C350 12
I had an ‘09 C350 4matic Fully stock, including exhaust. It had a nice slightly aggressive growl when accelerating moderately to hard. And was pretty quietest at highway cruising.
I moved on to a 2013 C350 4matic, also fully stock. It had a less aggressive growl when accelerating, at when highway cruising the exhaust note was a slight but noticeable drone, not like the ‘09. It’s not unpleasant, just different.
I moved on to a 2013 C350 4matic, also fully stock. It had a less aggressive growl when accelerating, at when highway cruising the exhaust note was a slight but noticeable drone, not like the ‘09. It’s not unpleasant, just different.
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Mercedes SL R231
If the exhaust is stock, there should not be a drone, regardless of speed. I have a 2014 C350 Sport (RWD) and have a relatively quiet ride. My 2015 SL400 has a nice rumble on startup and is a little louder than the C350 on the highway. Neither drones. Now, when I put a 3” turbo back on my MK1 Audi TT, it would scramble my brains. Had to put the stock muffler back on, but left the rest of the exhaust at 3”.
This problem seems exhaust related. Did you check to see if the exhaust from the manifold back is intact?
This problem seems exhaust related. Did you check to see if the exhaust from the manifold back is intact?
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C204 C350 12
If the exhaust is stock, there should not be a drone, regardless of speed. I have a 2014 C350 Sport (RWD) and have a relatively quiet ride. My 2015 SL400 has a nice rumble on startup and is a little louder than the C350 on the highway. Neither drones. Now, when I put a 3” turbo back on my MK1 Audi TT, it would scramble my brains. Had to put the stock muffler back on, but left the rest of the exhaust at 3”.
This problem seems exhaust related. Did you check to see if the exhaust from the manifold back is intact?
This problem seems exhaust related. Did you check to see if the exhaust from the manifold back is intact?
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C204 C350 12
i really like the noise it makes it must of had some exhaust work in its life at some stage it sounds like my old SLK32 with no back boxes.
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Mercedes SL R231
Thread Starter
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C204 C350 12
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Mercedes SL R231
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C204 C350 12
Just to update on this. The loud exhaust noise was coming from completely worn engine mounts. So none on bone at the perfect harmonious 60-70mph. Just updating if anyone else has this problem and comes across this thread.
