Evenmb

Yesterday I was driving on a quiet road and so, switch off the radio and everything to enjoy the drive. Slowly I notice that I can hear a dull humming noise. It's not very loud, but constant and gets a bit louder on acceleration. Most definitely it's from the engine.

Funny thing is, although I hv been driving this car since Dec, I haven't really notice the sound before. So I'm wondering whether has this always been there or something happenned? Most reviews I read praises this car's quiet cabin ambience so I am really confused. Did I get a lemon?

My dealer is suppose to get back to me if this is "normal" for this car, but I thought I can get some comments from other owners here as well.

StanNH

You sure it's not the tires? The RFT tires on this car are not known for their quietness. Engine noise, even with the 4, should be very subdued during normal cruising.

gocal73

Agree. These run flats are both harsh and noisy. Hope they wear out soon so I can get some real tires.

gncc193

Do you get the noise when the car is parked in neutral by raising or lowering the rpm"s? Or is it only during driving?

Evenmb

No, it's not the tires. The sound is dull but constant and quite clear if you have the radio off.

Yes, even when parked. It gets a bit louder on higher rpms. The sounds only stops with the engine off.

gncc193

I sent you a pm.

Evenmb

Thanks. But I'm not so sure though it's the fuel pump though.

Anyway I uploaded a recording of said sound. I held my handphone below the steering wheel near the footwells where I think the sound is coming from.

https://clyp.it/4zghfuld

Recorded in a quiet area with the car in P. As a comparison, I switched off the engine near the 20s mark so you can note the difference.

mdsbuc

I'm no mechanic, so my comment is probably worth a grain of salt. The sound I hear sounds high pitched, like that of a bad bearing in a water pump or something...

Evenmb

Wow...can the water pump go bad in such a new car? I thought these lasts years. You got me a little worried now...haha.

StanNH

No one other than your dealer can diagnose and deal with the noise you hear. Everything else is just speculation and guesswork.

It would be helpful though, to let the forum know what the dealer finds and what the fix turns out to be.

bluechappy

this c 300 is kinda quiet car if you using A(stop/start option) system lol however it has some certain Engine sound compared to Lexus and bmw.
I hear all the time the Engine's humming noise but can't recognize on the road that much and I always listen music when Im driving.

Evenmb

Just wanted to update this thread in case someone face a similar issue. Finally had the sound fixed. The dealer said there was some problem with the high-pressure fuel pump located near the front right side of the engine. The part was replaced and the sound disappeared.

voltdriver

Thanks for sharing, by any chance I can ask how you persuaded the dealer to change it ?