Rumbling noise - cause?

[redVENGEANCE]

I have a 2007 A4 2.0T Quattro.

6 weeks ago I could hear a rumbling noise at low speed say 0-30mph with slight vibration inside. Nothing major but just an annoyance.

Had my garage do an interim service and got them to look at exhaust.

Only issues found was 1 of bolts securing manifold was loose and had fallen into undertray. No other issues with exhaust.

Rumbling/vibration persisted.

Garage had car back. They can hear the noise and contacted Audi for advice. Not 100% sure but mentioned it could be engine mounts.

I get no knocking noise from front. No play on gear stick. Just this low rumbling noise and vibration on the left side. It sounds like you have to change gear sooner with the noise.

What are your thoughts on the cause?

 

[BarLyn]

I seem to remember having that on my B6, and it was the CV joint gone.

 

[redVENGEANCE]

I thought with the CV Joint you get a clicking noise when you turn steering. I get nothing like that. The exhaust just sounds a wee tad noisier than normal.

 

[D9n dk]

you get a rumbling noise if one or more of your tyres are out of shape and possible a slight vibration too

 

[redVENGEANCE]

All tyres are less than 6 months old and in very good condition with less than 6,000 on them.

 

[D9n dk]

id get it jacked up and check the prop shaft barring for any play

 

[Mike_B]

Cv / wheel bearing / propshaft bearing. All possible culprits.

 

[redVENGEANCE]

When I drove along at say 60mph the exhaust certainly sounds more throaty now. I can put car in neutral and the noise then goes as the car revs go to idle. Put her back into 5/6th gear and noise returns. Its not hugely noisy just sounds a bit louder than normal.

I don't think its anything to do with CV joints, engine mounts but is exhaust related.

 

[D9n dk]

Is the noise rotation related so if your driving along and you put your foot on the clutch while coasting does the noise disappear with the revs or is it still there while the wheels bearings etc are still turning

 

[redVENGEANCE]

The noise essentially disappears as the car coasts at 60mph with the clutch depressed. As the revs fall the noise does to.

 

[D9n dk]

So it's engine related if once the revs die down so does the noise so that rules out and cv joints and barring or tyres

 

[redVENGEANCE]

I would like to think its just exhaust related but there might be an engine problem. Its only done 67,000 miles. The engine power is still good and it pulls nicely.