Resonant "buzz" inside dash

[joe99]

My 2007 Mk7 TDi LWB has an annoying resonant "buzz" coming from somewhere inside the dash.

It only happens at speeds of around 100 km/h

I have tried placing my hand on each of the 3 hinged pieces on top of the dash as well as on the dash itself. I do not feel anything, nor is the noise affected in any way.

I have tried dropping the glove box lid right open and even removing the relay/fuse box cover all with no effect.

The plastic ventilation ducts behind the glove box seemed a bit loose so i secured them to each other with cable ties and this may have made a slight improvement but cetainly has not cured the problem.

When the noise is present, I can change down to 5th or even put the transmission into neutral and let the engine revs drop right down and the noise is not affected so it is definitely not engine related.

At lower speeds, everything is fine. In fact the vehicle feels smoother and there is less "noise vibration and harshness" than I would normally expect from a commercial vehicle.

Has anybody else had a similar problem?

How difficult is it to remove the central part of the dash (the piece the gear lever passes through) to look for any loose components behind it?

I should also point out that the vehicle has only done about 30,000k and as far as I can tell without dismantling anything, all the mechanical parts like wheel bearings, steering and suspension joints, uni joints are absolutely rattle free.

Thanks for any advice.

joe99

[ake]

Check and see if its the plastic scuttle panel, the plastic bit between the windscreen and the top of the bonnet

[joe99]

Thanks ake,
That plastic scuttle panel you describe feels quite firm and rattle free.

Crawling around under the vehicle and trying to shake things, the only "loose" components I could find were
(1) What appears to be an air conditioner hose which comes vertically downwards, just inboard of the windscreen washer bottle. It is held in place with a sort of black plastic "rivet" but which allows a bit of movement where it is attached to a small bracket on the chassis.
(2) What appears to be an engine coolant hose which runs across the vehicle just above the turbo intercooler. This is just sitting in place with nothing to stop it bouncing up and down.

However the "buzz" is so loud that I believe it must be coming from somewhere inside the passenger compartment. If it was coming from anything in the engine bay it would have to be incredibly loud.

Here are a couple of pics of what I am trying to describe. I hope the links work out OK.





Thanks again,

joe99

[trigger]

Wasp stuck in there somewhere???

[jay]

get either someone to drive or a good passenger to move round the cab while driving to find out where to noise is..btw do ths at night as if seen with a passenger in your lap or head under the dash could get a pull by local police

also check and make sure the extra fuse box under passenger side behind the glovebox the lid is properly fitted to the fuse box...you havent got some kind of traker fitted or hands free kit,as sometimes the boxes arent properly fitted and can rattle on something..

[Frag]

Check and see if its the plastic scuttle panel, the plastic bit between the windscreen and the top of the bonnet

I`m with ake,the rubber seal that runs along scuttle is usually only pushed onto plastic panel,
Remove it and refit over both the metal edge & plastic scuttle.
Try it

[soprano1982]

hi , ive had this prob before , on my own mk7 and works van , 1---if you have a roof rack cheak the radio ariel isnt behind a bar (touching) as you tend to fold it under to save shearing it off when using the rack - it can make a buzzing noise at speed , 2 the wiper blades sometime make a noise when the air gets under them , and ive also had the annoying noise coming from the rear view mirror/rain lightsensor housing ,i grab hold of it while diving and it stop the noise , hope this helps

[joe99]

Thanks for all those suggestions.
Unfortunately I cannot do any more testing for a few days as there are no suitable roads near my home.

As far as I am aware, I do not have a "rain light sensor". What should I look for? Which models is it normally fitted to? In any case my rear view mirror is not vibrating at all.

Does anybody have any comments on removing the central lower dash panel? There is one philips head screw on each side near the floor which I have not yet tried removing as I imagine there must be more holding the panel than these 2 screws. Even removing the ash tray (below the ventilation controls) might possibly help me to narrow down the source of the noise. Or can the ash tray only be removed after the large panel has been removed?

regards to all

joe99

[ake]

If you dont have auto lights or wipers you wont have a sensor, if you did the rear view mirror would be fixed to it

[Jeroen]

I had a similar problem, buzzing all over the front ... no matter what i did i remained. took out half the dash and found nothing ... i thought maybe something slipped into the crack between window and dash ... nothing there. so finally last week i had a crack in my window, took it to the car glass clinic and the guy said that that there where screws missing, front window wasn't fitted properly at all, they did not clean up good before installing new one, they used as little glue as they could ... now the buzz is gone! oh yeah that buzzing window was fitted by ford dealer ... . just to say that a buzz in dash does not always comes from the dash ... good luck hunting it down! took me ages and a crack in the window before someone else found what it was

rain sensor, put ignition on, set window washers in first position, take out the waterhoze and spray away ... if they move you got rain sensor. easy way, you should see a little circle on the glass at the back of the rearview mirror, car glass clinic guy looked at mine and said that a circle means rain sensor ...

light sensor should be on the right side of the steering wheel, mine's on the left ... european tranny

greetings, Jeroen