S4 (B6) - Odd Noise, High Revs

[CMW-S4]

I've got a bit of an odd 'problem' with my S4, anyone got any ideas on the following...

After a while of being driven hard, coming into 6-7k RPM range, there's an EXTREMELY deep rumble, doesn't sound mechanical, the gearing works fine, pulls like a train still, no slippage...and the noise can be recreated when parked up.

The noise (LOUD and DEEP) creates a vibration so much it can be FELT above the rumble (roar) of the V8 too

I had the car on a lift this morning and the exhaust doesn't seem to be blowing - at all in fact...I desribed the problem to one of the Audi dealer techs this morning and he's heard of nothing like it before (unable to recreate the problem for him to listen to)

A friend of mine bothered to extensively trawl Google (I'm good with Google - but what the hell do you even begin with for a search query on something so random?!)...and he's said he's seen a couple of mentions of mounts being a problem when the car is hot...didn't specify if it relates to engine or exhaust mounts mind

Anyone with any ideas?!

The car is with Audi on Thursday for an MOT and I'll bring the issue up with them to check out at the time - any suggestions in the mean time would be appreciated

Car is now on 123K, I had a B7 with 20K on the clock recently for a week and there was no noticable difference between the two in drive quality - oustanding ageing!! Recommend the S4 to everyone...be warned...petrol isn't cheap and neither is oil

[Pete.S]

I would wager a few quid that it's your alternator bearing. Had the same on mine around the same mileage. Bit of a pain (and expensive) to have checked but from your mileage & the symptoms you've described it sounds exactly like it.

[CMW-S4]

well the S4 went through the MOT fine, few advisors, mainly regarding bushes and the rear bump stops - signs of wear but not a problem

initial quotes for this work is ball park 2K...gulp...not required immediately though

as for the mysterious problem...apparently nothing in the logs...managed to recreate the problem again on the way home - definitely occurs at red line but the rumble felt through the whole car - i put the car in neutral was at speed and rev'd and the symtom was reproduced - so def not gearbox or clutch

i'll mention the alternator bearing to someone tomorrow and see what's suggested...someone also mentioned to me about the CATS...but i imagine this would have shown on the emissions on the MOT

car is fine under normal driving however

[chunky79]

Where abouts are you located? Could you get it to MRC or Unit 20? Both do work for most of the cars on this forum.

Dunc

[CMW-S4]

I'm based in Gloucestershire - but to be honest, and I'm sure I'm not the only one here...there's nothing better than driving the S4 - so anywhere between here and Poland is fair game for getting work done

I'll Google those companies

I'm hoping to get over to the stealership tomorrow...it's always a lot easier to have a Tech check the car over on a Saturday - especially first thing before they get on with 'real' work



Thanks!

[CMW-S4]

Well I found out what the problem was...the car is now on 129k and the problem was getting more frequent when driving the car hard

I just happened to have taken a job in the North West and thought it worth my time seeing Unit20. I'd also done a little research about gearboxes, clutches and flywheels - something was mentioned to me by someone, can't remember what or whom...but it was along the lines of a flywheel helps dampen the vibration from the engine

So...a quick chat with Martin & Lee at Unit20, and the over the phone diagnosis is clutch and flywheel...well guess what - my flywheel was blue, orange and rattled more than a babies toy!!!

I'm back at Unit20 tomorrow to get a CV joint sorted and then I'm back to happy motoring again...and able to play with Porsches again


Greets to MRC (Banbury) who I did visit in the first instance but I wasn't equiped with the knowledge/vocab to describe the problem and unable to recreate the to demonstrate either

Massive thanks to Martin and Lee at Unit20 for the extremely quick turn around on the work to date!

If anyone has any recommendations on short shift mechanisms for the S4 - I'd be glad to hear from you!!

[thrustin_justin]

Whats a rough cost for clutch and flywheel supplied and fitted if you dont mind me asking, I know these dual mass flywheels arent cheap

[CMW-S4]

Well I believe the parts breakdown to be in the region of

Clutch - 300-350
DMF - 600-700
Release Bearing - 50-100
Labour - 8.5hrs (this is the quote Audi workshop timing) (think Unit20 charge 45p/hour - which is considerably less than HALF my local dealership, who incidently won't work on my car any more...after a falling out during an insurance job I put through them...which the total bill to the ins co was around £4.5k!!)

I would speak to Martin @ Unit20 for a quote to be honest

The difference is incredible...the car feels so much more urgent - in all gears - oh and smooth...I had an auto on a 54 plate for a week a while back...it's just as smooth as that...except for the intermittant lag for gear change in my manual...which is why I'm looking into getting the guys to fit a quick shift linkage

For Info: the DMF is bloody heavy and is quite some piece of machining...mine was knackered...I think 700 quid is cheap considering what it does and the kind of of mileage mine had done

[thrustin_justin]

Thanks for the info

I almost certainly have a fault with my flywheel, car is extremely jerky if you try and pull away quickly in 1st and its been like this since 44k miles

Apart from that, my S4 has been awesome!!!

[chunky79]

These motors are very hard to drive smoothly so don't think the fly wheel is gone just cause of that.
If you drive a different vehicle all week and only use the S4 at weekends people could easily mistake you for being learner when you pull off, i know my wife thinks i am