Knocking sound

Au2ro

Au2ro

Member
Tarkus has just developed a knocking sound. It increases in frequency with road speed, not engine speed. It is intermittent and I can only hear it occasionally on my commute and not every day yet...
It seems to be more prevalent turning to the left and I especially remember hearing it turning on to and off from roundabouts not while going around them.
No work has been done on it recently.
Any ideas?
 
"Is your undertray loose?"
No, I haven't got one, and I know the sound that my loose wheel arch liners make, and unless they have lost some screws and have slipped it does not sound like that. Though I suspect some screws are missing so I have some spare fasteners to fit to my wheel arch liners but the weather has been too bad to fit them.
 
From the description of when it happens, I'd be thinking driveshaft/CV joints, in which case best to get it looked at pronto. You don't want to be driving it when one of those goes.
 
CV joints? Tighten everything up then go to a supermarket car park at the quiet end and drive it around on full lock and see if you can replicate it. If so probably CV joints.
 
Thanks, all, I will remove the wheel (I think it's drivers side) and check for anything loose, put the wheel back on and see if I can replicate it (weather permitting). I was hoping that it was not CV joints but if I can replicate it then it's straight to the garage next week. It's just a pain that the weather is so bad - my commute without the car will be horrible.
 
Top mount? Mine is rattling away on the near side, I’m still trying to summon up the enthusiasm to replace mine.
 
Howey said:
Would not think a top mount could rattle but who knows?
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Fair point, assumption is the mother of all f**k ups but it’s what I believed was causing the annoying rattle/clatter/whatever noise. I’d love it to be something simple like a loose bonnet, and it’s just passed an MOT so it can’t be something too terrible.
 
Silverpig said:
Top mount? Mine is rattling away on the near side, I’m still trying to summon up the enthusiasm to replace mine.
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I know what a top mount bearing sound makes when it is failing, Twang Kung Boing... when you turn the steering wheel.
I did think that I heard it again recently and was wondering if it needed doing again but I am not sure that this knocking could be related. I have had my top mount bearings replaced a couple of times but never heard this knocking noise before, this is just just a knock knock knock knock knock knock increasing in frequency with road speed.
 
Au2ro said:
I know what a top mount bearing sound makes when it is failing, Twang Kung Boing... when you turn the steering wheel.
I did think that I heard it again recently and was wondering if it needed doing again but I am not sure that this knocking could be related. I have had my top mount bearings replaced a couple of times but never heard this knocking noise before, this is just just a knock knock knock knock knock knock increasing in frequency with road speed.
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Ah, interesting! My silver one makes the ‘twang boing’ noise which we assumed was a broken spring, but it’s been examined and the spring is fine. Dolphin grey is making the rattling sound which again I thought was the top mount, as I’ve had other VAG cars which have made the same noise and it’s turned out to be worn top mounts.

When we have a break in this miserable weather I’ll check the bonnet and other areas in the offside to see if it could be anything else. I’d love it NOT to be a top mount as it appears to be a pain of a job. Is there any other way of telling? Perhaps we could have a ‘Definitive Noise Guide’ like the ‘Definitive Wheel and Tyre Guide’ for future reference?!?
 
Twang kung boing is the best reference to the noise I've ever read, it's bang on the sound I'm getting on one of my A2s after it hit a deep pothole at speed.
 
So today I managed to get out between sleet, hail and snow showers and got the front drivers side wheel off. I could not see anything obvious and the bolts seemed quite tight enough while taking them out (I will get out later, weather permitting, to check the rest of the wheel bolts).
Anyway, my drivers side front wheel arch liner was worse than I thought with an obvious scrape from the tyre to the front engine bay side. There was literally nothing but a cable tie holding up the liner on the front inside of the wheel arch. As I was trying to manoeuvre the liner to line it up to the fastener holes a couple of fasteners fell out from behind, I guess that these short fasteners are meant to be holding the soundproofing on somehow?
I managed to get a couple of new fasteners into the front lower holes and re-tie the cable tie but there was no way I could fasten it on anywhere else. Where lower hole under the engine bay should be the plastic was broken so I could not get a fastener in there and there did not seem to be any other holes in the liner next to the engine bay apart from one at the top but the hole was blocked, probably by a sheared screw.

There were several screws and fasteners holding the liner on to the rear of the wheel arch and only 2 needed replacing, though at least one screw seemed just to turn around in the hole - I guess that the metal clip behind it had rusted away.

I did what I could and took it for a test drive counter clockwise around the village so I had to negotiate several tight left hand bends but I could not get it to make the noise, however the noise is intermittent so the test drive was inconclusive. I suppose it could have been the liner rhythmically bouncing against the tyre but it sounded to be more regular than that.

So I think that I at least need a new wheel arch liner.
 
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