Quattro rumble getting worse

[Spitfire007]

2016 A6 3.0T. 70k miles.

When I bought it 3 years ago at 37k miles there was NO noise or vibration at slow parking lot speeds whatsoever. I couldn't tell is was Quattro AWD.

Got the car back from an oil change 2 years ago and felt a little rumble in tight parking lot turns. But it felt ok.

Now it's getting slowly worse. Feel it when accelerating from a stop sign and making a tight 90 deg turn onto a street.
Sometimes it's pretty irritating, sometimes less so.

I have had a dealer look the car over when I got new tires, they had nothing to report other than very slightly leaky front lower control arms.
All engine and trans mounts are good.
Tires are new Michelins.
Alignment was done to spec and it's holding.
No lights, no codes whatsoever.

Wtf. It's getting worse and makes me cringe when I feel it. (Noise/vibration)

Makes me wanna throw the car off a cliff.

Where do I look? What do I do? Something is clearly off but no one can find anything.


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[A665]

Check your wheel bearings.

[Botbasher]

Leaking at the lower control arm??? Nothing down there to leak except a CV and the shock and they don't leak!

Do you have any issues at speed? Vibrations, drifting, wobbles or noises?

Due to the geometry of the multilink suspension the cars will scrub at slow speed at some level. The tighter the turn the worse I have found. They are designed to drive fast smoothly... not get groceries quietly.

When you get into the twisties, do you notice the noise/vibrations?

I've had 2 A5s, an S6 and a CC that have all done very similar to what you describe. Slow speed tightness and scrubbing. Never had an issue with wear or alignment though!

No real solution but know you are not alone.

Cheers,

KS

[Spitfire007]

Yeah. Tech even sent the little video walk around. I guess the bushings show some liquid/grease if they're worn? But said it wasn't a pressing concern.

No vibrations when driving normally, none on highway unless under braking (warped rotors/bushings). No noises.

It's a mid-driveline, seat of your pants vibration/rumble noise under throttle when pulling away from a stop IN A TURN ONLY, under moderate to full (but not forced) steering lock.

Don't know if I'm describing accurately.


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[Spitfire007]

Just reconfirmed via tech's video: purple fluid leaking from guide bushings. (The big ones)....but I don't think this is related.



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[joserod92]

Just reconfirmed via tech's video: purple fluid leaking from guide bushings. (The big ones)....but I don't think this is related.



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what are the guide bushings?

[Botbasher]

Purple fluid is motor mounts... Post the video on YT and link it so we can see what you are talking about.

Mid... under your seat... Driveshaft Carrier bearing. 2 minute mark. Known failure point. Quick diagnose and easy fix. Look for the JHM Driveshaft Carrier Bearing

That would get worse over time... would be louder under loading from turns... and sounds like it right under your a$$ (because it is!).

Hope that helps! I hate noises from cars... especially ones I can't figure out. I feel your pain!

KS

[Botbasher]

And the next post down in the forum...

https://www.audizine.com/forum/showt...Billet-Upgrade

Coincidence... I think not!

Cheers,

KS

[Spitfire007]

Image1656085839.430364.jpg

IMG_2763.jpg


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[Botbasher]

Image1656085839.430364.jpg

IMG_2763.jpg

That's your rear trailing arm bushing for the front suspension. There is nothing there to leak. That fluid is traveling.

Purple is what most describe the color of what comes out of the active motor mounts. You probably have a failed motor mount. Not uncommon, but not exactly an easy/cheap fix.

From your description, I would get under the car and push around the driveshaft a bit and see if it moves like in the video I linked.

You may have multiple issues stacked up causing your noise!

KS

[Spitfire007]

Yeah. I figured they didn't know wtf they were talking about....but you'd think Audi techs would KNOW a mount is bad, vs a bushing not having fluid to leak...
Unreal. At least he did a good job on the tires.


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[Spitfire007]

Purple fluid is motor mounts... Post the video on YT and link it so we can see what you are talking about.

Mid... under your seat... Driveshaft Carrier bearing. 2 minute mark. Known failure point. Quick diagnose and easy fix. Look for the JHM Driveshaft Carrier Bearing

That would get worse over time... would be louder under loading from turns... and sounds like it right under your a$$ (because it is!).

Hope that helps! I hate noises from cars... especially ones I can't figure out. I feel your pain!

KS

Hey this is super helpful. Thanks a lot!


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[Spitfire007]

That's your rear trailing arm bushing for the front suspension. There is nothing there to leak. That fluid is traveling.

Purple is what most describe the color of what comes out of the active motor mounts. You probably have a failed motor mount. Not uncommon, but not exactly an easy/cheap fix.

From your description, I would get under the car and push around the driveshaft a bit and see if it moves like in the video I linked.

You may have multiple issues stacked up causing your noise!

KS

I think you're right on.
I do drive it hard...

Thanks a lot for the insight. This forum is very helpful


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[Audibot]

There is at least one fluid filled bushing on these cars. Front lower control arm, for instance.

[Botbasher]

There is at least one fluid filled bushing on these cars. Front lower control arm, for instance.

The one I got for my eventual suspension rebuild is not fluid filled... but according to Audi there is a VIN break for them, so maybe some are? Maybe it's an A to S difference? Maybe I got the wrong one??

The only purple fluid I have heard talked about is in the active motor mounts... but it's Audi... you just never know!

Cheers,

KS

[Botbasher]

Well... Audibot may have some insight too...

If they are fluid filled on yours, then that could be your low speed grumble in turns (as it makes hard contact to the frame)... and the mid-driveline could be carrier.

Or it could be a motor mount involved too!

Again... sounds like you may have multiple layers of this onion to peel back! Only a through, unrushed inspection can tell!

Cheers,

KS

[Alabama]

You probably have a failed motor mount.

Has the car been scanned for codes? I believe a failed motor mount should generate a DTC code.

[Spitfire007]

Has the car been scanned for codes? I believe a failed motor mount should generate a DTC code.

No codes. No soft codes. Nothing so far. Passenger side motor mount was changed 2 years ago under original warranty by the dealer and there were no codes associated. I think it had to fail catastrophically before it throws a code.



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