Hi,

     I've posted on this before but wanted to raise the issue again now I have had a year of ownership.

 

We own a 63 plate Superb Estate (Elegance spec) . 20000 miles, good condition, running well. It's the 170ps engine with DSG and 4x4 options. All in, a tremendously useful car.

 

Only issue that detracts is that it has always been noisy on the motorway. Up until around 60mph it is quiet with only the expected tyre and wind noise. As you get towards 70mph though  (just over 2000 rpm) the engine/exhaust noise increases significantly and you hear a steady drone from the front of the car. Several people have mentioned this unprompted while in the car so, for a change, this is not just my OCD. 

 

I've been down the usual tyres/tracking path and am confident it is not this for a couple of reasons:

 

1. Had tracking checked and it is spot on.

2. Tyre wear is even without any signs of scrubbing

 

For all the world it sounds like having a small hole in the exhaust but I have not been able to locate anything like that.

 

Reviews I have read suggest the car is generally judged to be pretty quiet at all speeds plus my mate's 140ps 2wD manual car is definitely quieter than ours. Does anyone have any thoughts/experience that might explain what is going on here?

 

Cheers,

 

iep

 

 

Edited 7 May, 20188 yr by iperry

Warped brake disc(s) ?

Wheel bearing(s) ?

 

Search forum - there are few threads.

Edited 7 May, 20188 yr by jafo

Ta, but brakes and bearings are all good. Brake discs have been replaced and noise did not change, Grage gave the bearings a once over while doing the discs. Also noise does not vary when cornering or changing lane (as wheel bearing noise usually does).

 

It definitely sound more exhaust note related. I wondered if the 170ps engine (which I gather has a larger/different turbo) might just be nisier?

 

iep

I never noticed it and I had two 170 TDIs previously although mine were FWD.  Have you had the haldex setup checked - could be a differential issue if its coming from the back end?  Was the turbo itself checked for any wear or damaged seals etc.  Also, is the DSG box working okay and has the oil been changed?  Just a few thoughts that spring to mind.

We have yours as L&K. It is quiet on the motorway. I had a "noisy" V70 in the past and it turned out to be the Continental SC 4 or 5 . After a tyre change it got quieter.

What does your car sound like at standstill at around 2000 RPM? Any noise / drone then?

Is it noisy on any motorway or just on certain ones? It could be noisy tarmac.

Hi,

    Ta for responses. Comments below:

 

1. Noise come from front of car, no indication it's diff related. It's also RPM rather than speed related.

 

2. No checks on the turbo but noise is unchanged over the last year so I don't think it's likely to be a turbo issue (I'd expect that to get gradually worse). It's only 23k miles too so should be in good order.

 

3. DSG box running great. DSG oil changed 6 months back. I also change the engine oil every 6 months (did I mention my OCD?).

 

4. I don't think it's the tyres. Car came with a cet of contis and I have since switched to a full set of nokians. No change in cabin noise.

 

5. Engine sounds fine at tickover. Revving to 2000rpm when in park doesn't show much. I get the impression the engine needs to be 'loaded' to recreate the sound.

 

6. Noise present on all road surfaces.

 

Could it be engine mounts?

 

iep

could be that something produces a resonance at a certain vibration/load level.

i remember someone reporting something similar and the garage suggested to replace one of the 3 engine support (buffer) parts. There's one left, one right and one kind of low middle.

 

you could take it to a dyno garage, simulate some speed and have someone go below deck and listen for resonance sound while you sit in passenger's seat.

they have rev limiter anyway when parked, so you need to go above 2500rpm limit somehow, hence the dyno idea.

while on the dyno you eliminate suspension/wheels/steering components anyway so it could be easier to track down if you still hear it.

Edited 9 May, 20188 yr by zice

Ta, that's helpful. Gave it a bit more thought yesterday. Basically it occurs based on engine revs and engine loading (not wheel speed).

 

From that, it seems (to me) possible that it is exhaust or engine mount related.

 

Not sure what else would be affected by this combination of engine revs and loading.

 

How easily can one of the engine mounts be replaced? Homer job with a jack under the engine?

 

cheers,

 

iep 

17 hours ago, zice said:

while on the dyno you eliminate suspension

 

This one would actually be pretty hard to eliminate on the dyno ... you can do that on the MOT checks (a vibration plate test - which are sometimes free, if you just want to check your suspension):

 

https://www.youtube.com/watch?v=S2cku5nibvc

Edited 10 May, 20188 yr by vborovic

1 hour ago, vborovic said:

 

This one would actually be pretty hard to eliminate on the dyno ... you can do that on the MOT checks (a vibration plate test - which are sometimes free, if you just want to check your suspension):

 

https://www.youtube.com/watch?v=S2cku5nibvc

 

what i meant by eliminating is to take it out of the troubleshooting process by NOT being able to test it (or be influenced by it)

basically forgetting about it (as well as steering, etc) and just test engine/revs/vibrations/exhaust, etc...

This now makes more sense, but following that logic, you can't really say that the wheels are eliminated (warped tyre/rim, or a faulty wheel bearing, etc.) ... steering, ok in that case

2 hours ago, vborovic said:

This now makes more sense, but following that logic, you can't really say that the wheels are eliminated (warped tyre/rim, or a faulty wheel bearing, etc.) ... steering, ok in that case

 

warped tyre/rim, bearings will rotate on the dyno, therefore they're still in.

there's no other way to stay under the car at 100km/h and carefully listen for resonance induced vibrations

 

first stay in the passenger seat and listen...if you hear it then go below deck and try to locate the source.

oh yea, besides the engine buffer parts, check also the air intake hose (right at the front of the bonnet). Some guys said if it gets slightly loose, it may cause strange noises.

Edited 10 May, 20188 yr by zice

Thanks, I'll check the air intake.

 

Had a lift in my friend's Superb last night (140ps, manual, 2wd) and it was so much quieter than ours.

 

Something has to be awry I would think. 

 

iep

On 5/10/2018 at 17:47, zice said:

there's no other way to stay under the car at 100km/h and carefully listen for resonance induced vibrations

 

GoPro and a Shure microphone ...

I`ve had what I`m thinking is a similar noise coming from the engine bay of my 2.0L CDR. It sounds like to me the exhaust has blown but after reading this thread I finally decided to investigate.

 

I found the noise I was getting is coming from a longish plastic box at the front of the engine bay. If I press down on it the noise goes away as per this Car noise.m4a file. I haven`t decided what to do about it yet but I`m glad its not an exhaust problem.

 

Edited 16 May, 20188 yr by ashfan
Clarity

19 minutes ago, ashfan said:

I`ve had what I`m thinking is a similar noise coming from the engine bay of my 2.0L CDR. It sounds like to me the exhaust has blown but after reading this thread I finally decided to investigate.

 

I found the noise I was getting is coming from a longish plastic box at the front of the engine bay. If I press down on it the noise goes away as per this Car noise.m4a file. I haven`t decided what to do about it yet but I`m glad its not an exhaust problem.

 

 

That's the cold air intake plenum.

I have read comments somewhere - maybe not this forum - about a droning noise being due to vibration/resonance in the air intake. Putting "intake noise" into Search brought up quite a few comments on intake rattles and noise.

I was taking a look at that very part of the air intake last night. It does seem to be relatively loose and prone to vibration. Might also explain why it seems worse at speed (more input air turbulence)

 

Ashfan, how much pressure do you need to apply to the lid of the box for it to quiet down? Is it just the lid vibrating (so a cable tie might do it) or is it the whole box do you think? 

 

Something in the air intake does 'feel' about right given the symptoms of the noise.

 

Cheers,

 

iep

Ashfan, I just noticed your audio clip (thanks for that btw, top foruming). That sounds a lot like what I'm hearing. I'll take a look and report back.

 

Cheers,

 

iep

It seems to be the whole box thats making the noise. I mostly can hear it when the car is fast idling or pulling away so low revs. When I`m cruising on the motorway its silent, apart from the normal diesel engine noise.

 

I wedged something against the seat and pedal until the noise appeared. I didn`t need to apply much pressure to stop the vibration

Ta, I might try adding some tape to the rim of the box/lid and around where the output tube connects to make them a tighter fit. See if I can stop the vibrations that way.

 

iep

Took a look and while it 'moves' the box is well attached and damped and does not rattle or resonate. Tried moving through the rev range etc and no sign of any vibration from the air intake.

 

iep

Seems like this has been covered before! This post describes exactly what we're seeing with our car:

 

 

 

Hi, 

 

I've just change my gearbox mount in my octavia for exactly the same reasons you describe. I had low resonating frequency when stopped and idle, between 2000 to 2500 revs, only when underload it is really noisy, noiser than any car I've had before. 

 

When I took my mount out, it was clear it was gone. Twisting a little and moved an inch, inch and a half with a pry bar. 

 

The car does seem quiter right now but £120 and 2 hours fettling with it, wishful thinking might be skewing my opinion. 

 

Ill report back after ive done a few miles and let you knoe if it made any difference. 

 

 

Regards, Simon. 

I have something similar with my manual 170bhp 4x4. At 2200 revs in sixth only there is a slight vibration/rumble from the rear. Change to fifth or stop accelerating it goes away? Prop shaft has been checked and seems ok