Wet weather knocking

[toaophil]

2014 S3 Quattro

hi all

I’ve seen similar posts on this but not always for this chassis. So thought I’d ask a ‘fresh’

In heavier wet conditions, puddles or standing water in general, large spray on motorways… my s3 starts a loud knocking from somewhere underneath. It sounds like front/middle. It last quite a few seconds, maybe even up to 30 sec if very wet.
It’s not on the engine revs, it will carry on if knocked into N
I also think that when it happened today, I was able to stop it by accelerating.

I’ve read about rapidly cooking exhausts and of course haldex concerns. A note to add to that, it’ll do it even at lower speeds so I don’t think it’s to do with aqua planing/grip. I’m proper worried about the predicted replies for this!
I have got a video which I’ll try and put up
Thanks in advance though

 

[Jcbmally]

Suspension/gearbox mount ? More prominent when wet ? Apart from that I’m struggling to see why it only happens when raining. You’ve definitely ruled out a traction judder ?

 

[toaophil]

Well I definitely worried about a traction judder, but like today, I can’t believe the car was struggling for traction. At one point was probably doing under 25mph in a straight line. And it was wet, but not aquaplane wet.
Gearbox mount is an interesting shout, cheers. I believe the gear box was dropped out when it had done warranty work done.

 

[Jcbmally]

I wouldn’t imagine it could be much more mate. If it were gearbox it would do it all the time, at least the mounts are not that expensive so maybe process of illumination to start.

 

[toaophil]

So could be the box/mounts?? It’s only in wet conditions, nothing when dry!

 

[Jcbmally]

So could be the box/mounts?? It’s only in wet conditions, nothing when dry!

Could be mate, manual or DSG ?. In the good old days you would see the gear leaver moving if any mounts were starting to go, Had it happen in an old XR2 once, but that did it in the dry as well. if you rule out traction and suspension then not sure what else especially when you say it’s only when raining. Exhaust would do it all the time I would imagine. Hopefully some other peeps on here can offer something up.

 

[toaophil]

Ah ok. Yeah it’s DSG. And yeah only when wet. A few puddles around won’t do it. But heavier surface water and boom. Strange also that I think that it stopped it when I pushed the throttle

 

[Jcbmally]

I’d still check the mount, long shot but if BIG water gets in there then maybe it would. Have you also checked the under tray ? Nothing slack ?

 

[toaophil]

I think it’s missing the main undertray. I wonder if even that contributes to the problem…!

 

[Jcbmally]

Undertray does keep most crap etc out.

 

[AudiRace]

Ah ok. Yeah it’s DSG. And yeah only when wet. A few puddles around won’t do it. But heavier surface water and boom. Strange also that I think that it stopped it when I pushed the throttle

It is your exhaust ... Check exhaust it is loose

 

[toaophil]

It is your exhaust ... Check exhaust it is loose

I really hope so!