B6 S4 rattle from bay

[graney15118]

Hi everyone, I'm new to this forum as i have only had my S4 about 2 weeks. I am loving it like, went from a Golf R DSG to this for needing the space for band gear (i got an avant) and i haven't looked back! And as a bonus, it came with B7 RS4 front brakes and a milltek system (don't know if it's resonated or not, but it's loud!)

Anyways, the car is great apart from 1 issue. Regardless of engine temperature, at engine speeds of 1200rpm and 1800-2000rpm, there is a rattle coming from what sounds like the front LHS of the engine. It doesn't affect engine performance or anything, and it doesn't sound particularly mechanical (i know about the chain rattles! ) it's just bloody annoying! I think it's a piece of trim somewhere or something like that, or at least thats what i'm hoping!

Just wanted to know if anyone has had this before or might know what it is? I just don't want to have to start pulling the front end of the car off to find it!

Any help would be greatly appreciated!

Cheers

[graney15118]

Anyone got any ideas??

Would be much appreciated

Thanks

[Colinurquhart]

You might get a response over on audisrs.com regarding this car as there's a bit more activity. Hope you get it solved.

[graney15118]

Thaks for the reply mate, I'm currently in the process of talking to JHM about it

[hlbeckley]

JHM will help
Sounds like chain tensioners
Well documented with these engines! Call MRC or grizz at unit 20, sure they can diagnose

[graney15118]

Cheers for the advice mate, i must admit, i have heard one with bad tensioners and it doesn;t sound like mine. I saw a video of a guy on YouTube the other day and there is some kind of vacuum operated valve at the front of the engine and when he disconnected the vac, the noise went away, and it sounded like the noise i'm hearing. Gonna check it out tonight! Any idea what this valve is for by any chance?

[Batfinnk]

I believe it operates the flaps inside the inlet manifold. Mine was making a funny noise from that sort of area when the timing chain had jumped a tooth. Worth getting the car scanned to see what if any fault codes are in there.

[graney15118]

Ah cheers man, I have had it plugged in and there's no fault codes, would there be a code if the chain had jumped a tooth? The only real effect on the car is the throttle seems to lag a bit when you release it but I dunno if this is because the flap needs a clean, I've read this can be an issue

Cheers

[Batfinnk]

Mine threw up P0340 and P0345 and ran really rough and was noticeably down on power.

[graney15118]

Ah, well with the greatest respect to you, as I know you've had to shell out recently, I've read the thread! that eases my mind a little as there's no codes and no loss of power, hopefully I'll have it sussed and sorted soon!

Thanks for the replies

[bazzabear]

The rattle, and the area, sound familiar to me - although the revs are different. Still, it might be this.

My wife's car had a rattle from exactly that area at about 2500 rpm. It turned out to be a bolt holding the alternator in place had worked loose (and in fact, by the time this was diagnosed, it had sheared two bolts.)

Cost for parts to fix it £3. Cost for labour to fix it £300 (had to take the front off the car!)

[graney15118]

Ya know what it is, I was just thinking about this thread the other day and I've noticed that if I bury the throttle then at about 6000rpm the battery light comes on intermittently, these two things might be related! That is what was making me think it was the aux belt tensioner, but a loose bolt on the alternator sounds more feasible, especially if it has happened before!

Thanks for the reply man

[bazzabear]

No worries. Good luck!

[graney15118]

Well, suspicions confirmed, it was exactly that! Alternator bolt snapped in 3 places! Thankfully I have a warranty with the car so it's covered, more importantly the alternator is not damaged, just the bracket! The car is in the garage getting sorted now, he says it's a right pain of a job like, but hopefully should have it purring quietly very soon! Thank for the advice and replies fellas! Can't wait to get it back now!

[graney15118]

Here is a picture of the damage, all fixed now:



Has this happened to anyone else who has a B6 or B7? I'm thinking of writing to audi since I think the bolts should be shouldered considering what they have to do, threading the bolt all the way to the head will reduce the strength and has ultimately resulted in a hefty bill on my part. I wouldn't mind a few more cases to have as evidence and maybe it will sort something out for us all to benefit from, such a recall to nip the problem in the bud, or maybe compensation for anyone that has had to shell out to have this repaired as I have. It might lead to nowhere but you never know until you try!

Thanks again for the replies and taking the time to read my thread

Cheers