Help - noise from my W204 C350 CDI is driving me nuts !

[wadaw]

Hello everyone, I've been lurking here for a while and have found this forum very informative - please accept my apologies for my 1st post being a plea for help !

I recently sold my much loved S204 C180K for a W204 C350 CDI, 2010 registration.

The C350 has 18" AMG wheels, with the lowered suspension and big brakes. Overall the car drives great except for 1 problem, which is driving me mad.

There is a constant droning noise (that sounds like when air is blown across the opening of an empty bottle - stupid I know...) that starts as soon as the car is moving and is noticeable all the way upto approx. 70mph. It appears to be coming from the passenger front wheel area.

It does not vary with speed, seems louder at certain speeds (40-50mph), does not change or disappear with left or right turns.

I originally thought it was tyre noise from the Nexen tyres it had on it, which I replaced with Goodyear Eagle F1s, which did not make a difference.

Before I purchased the car it was taken on an extensive test drive and I did not detect the noise. The only activity performed between then and now was its scheduled gearbox service before I collected the car.

I would really appreciate any views / help.

 

[stumpy1]

I would've said tyres, brakes, gearbox or bearings and these are easy to check. However we once had a BMW which did something similar and it turned out that there was a missing weld on the firewall which was letting the air in.

 

[wadaw]

Thanks. I've checked the wheel bearings and they seem fine - there is no play or noise that I can detect.

The gearbox seems fine also, no strange noises upon engaging drive - shifts are smooth up and down.

One thing I did notice is that there is a noticeable knock at several positions when turning the steering to full left lock, this can be 'felt' through the passenger footwell ....

 

[6cyl]

Does road surface make any difference?
Does the noise vary in pitch at all ?
CV joint (equivalent) may be?

 

[wadaw]

Road surface makes very little difference, the noise does not vary in pitch just intensity - particularly horrible @ 40 - 55 mph, but noticeable from a crawl onwards - at motorway speeds it seems to vanish.

 

[micke]

Possibly a long shot, but worth checking.......
The car needs to roll to reproduce, but disappears a higher speeds (probably not audible above all other rolling / aero noises, this could be brake drag - the pad rubbing lightly on the disc.
After a drive does the LF wheel / disc feel hotter than the RF **Don't burn fingers!!**
If you jack up the LF corner, does the wheel resist spinning (this could also point the finger at the wheel bearing)?
Finally check the stone guard behind the disc is not rubbing on the disc - this can make a good howl!

 

[wadaw]

ok, I've checked so far :

All brakes and stone guards ok.
Jacked up each corner to check the bearings, no play or excessive noise.

I have also road tested with a friend to listen with a stethoscope, it would appear this is coming from the rear passenger wheel area. Upon jacking up that corner and rotating the wheel, there is a horrible grinding noise for a fraction of a second - that then stops upon further wheel rotations. If I drop the vehicle back down and jack it back up, I can repeat the noise.

So my guess is a failed bearing or drive shaft problem - any further checks I can make before I start spending on parts ?

 

[wadaw]

Well, have taken it to two specialists who both insist this is tyres noise! I am somewhat surprised by this as its quite terrible, no other car I've ever had has made noise like it.

Guess its time to drop the 18" amg's for something smaller?

 

[V12]

You already replace the tyres for a new set of Goodyears.

Why would a second set make exactly the same noise?

 

[ioweddie]

try folding in the wing mirrors

 

[AndyPCD]

One thing i would check is the handbrake cable has not come unclipped and is touching the prop shaft.

Have seen it quite a few times on the 203 chassis