Thread: Mystery sound in my D4

Originally Posted by CaverD3

Idler pully bearing shot? Common occurence.

It's only a few weeks old? I'll raise it when serviced or earlier if it persists. Thanks Ron.

Just a long shot but the main hydrostatic engine cooling fan comes on intermittently in my D4 and has that low down hum that you can hear driving along. I only hear it under 60kph. Could it be this

Hi whatpub,

In one way i am happy to read your post. I have the same difficulty describing the change in sound and feel that my D4 developed during a recent long trip. I describe it as:

Inconsistant
Slightly worse when cold
Happens under moderate acceleration at slow speed
Slightly worse when driving up a steep hill
Creates a turbo like sound but slightly sicker sounding
Creates a vibration that at one time i could feel in the car
Doesnt seem to effect anything else. Power good. No smoke. No oil consumption.

I reported it at my service this week. Very good dealer service. Lead mechanic came for a drive and heard the sound. They investigated but could not isolate it. They took note on my service record and asked me to monitor and come back if it gets worse.

Its not bad enough to say its a significant problem. It is just that it wasn't there before and it is causing me concern.

My car is a 2010 D4 TDV3.0 with 37Ks.

Has your noice got better or worse? Any answers or solutions?

Well I think I have the same sound/vibration, and had put it down to tyres. I asked the dealers and they just fobbed it off.

My sound is a bit like going over rough edge markers that we get on the major roads, but not as severe.

You can both feel and hear it.
It only occurs around the 50 to 60kmh range
Seems to not be there when the roads are wet?
More likely to be there when coasting or slightly decelerating
Is still there if car is put in neutral.

I rarely notice now, but did the other day when SWMBO asked about it, so I'm not sure if it's there as often now? I don't think so? (now at 15k) My 2010 D4 had the same tyres and engine but I never noticed the sound or vibration. I had however moved from a 2001 Td5 D2 so it was very, very, very quiet in comparison.

Hi RoverLander,

I reported it at my first service and it was suggested that it was just normal "resonance" (whatever that may mean in a vehicle!). It was even quipped that I turn the radio up if it annoyed me too much!

To be honest I've either adjusted to it or it's gone away. I certainly don't notice it any more.

I did ensure though that it was documented at the service just in case it flares up into something serious in the future.

However, now that my touch-screen (and therefore radio, GPS, bluetooth, cameras, etc) have died - see recent post - I may notice it again!

Ron

Mine makes what sounds like a similar hard to notice noise at slow speeds when you excellerate away slowely or with a on again off again trailing throttle. Go for a drive with the drivers window down and I bet you can hear it quite loudly compared with the window up. That is if it is the same noise and yes you can feel it very slightly through the steering wheel when the noise happens. Well you can on my D3 anyway.

Mind you my airconditioning compressor just failed so once it is fixed it will be interesting to see if it the nosie and the vibration goes away.

The thing is most everyone always drives with music on and you can't hear it with the radio on, so maybe it is quite common and nothing to be worried about.

cheers,
Terry

Originally Posted by AnD3rew

since you mention the pothole, it could be wheel alignment

Is the steering wheel still straight? A slight whirring sound could easily be caused by the alignment slightly out. Although not a conclusive indicator, I'd expect the steering wheel to slightly off centre though.

The slight cupping on the outside edges of my front tyres causes minor noise and vibration through the steering wheel at slowish speeds on some surfaces so its time the tyres got shuffled.

I've done a bit more testing on this....and I think it is engine or transmission related. It happens around 50 to 60Kms per hour and when going from coasting to moderate acceleration.

Aircon on or off makes no difference.
I have put it in manual at that speed and there is no noise. I dont believe it is a tyre noise.

I will get a wheel balance and allignment in the next few weeks when I get a TPMS installed and see if that makes any difference but I suspect it wont. I'll post any updates here.

Peter