Strange noise when releasing accelerator??

[norris_309]

Hi,

I've recently been noticing this odd noise, it's like a spinning/grinding sound. Kind of like the noise you hear when your brake pads are worn out & rubbing the discs (it's not that by the way!) it seems to be coming from the drivers side front.

At first I thought it was something to do with the clutch as it seems to happen when pushing the clutch in to change gear & you mainly hear it going from first to second.
I've since realised it actually may happen when you let the accelerator off (so same time as pressing clutch)
It's not a loud noise at all but i'm sure it never used to do it.

Driving to work today I kept letting the accelerator off when in first & second & you could hear it then regardless of pressing the clutch. and it seems to change in how bad/loud it is, sometimes not actually making the noise??
I'm confused?? any ideas... anyone else have this?

 

[Ro55]

Something rubbing?
check mounts,driveshaft also look at alternator clutch.
done any work in that area lately? arch liner? could be anything really
Does it happen at idle? or only moving?

 

[norris_309]

Not done anything to it for a while, but I've only really just started driving it more now (the mrs has been using it... I blame her!)
It doesn't sound like rubbing of the arch liner type, the alternator clutch was replaced just before I bought it last year. And having had that problem on my golf too it doesn't sound like that.
And it doesn't happen at idle, only when moving. I'll try taking it out of gear when rolling to see if it does it then... could it be gearbox related? (god I hope not!!)

Driveshafts?... could be I guess, as it is a 'rolling/spinning' type sound but it's too fast a noise to go with the rolling speed of the car if you know what I mean. That's what led me to think clutch as I thought a release bearing might cause that kind of noise??.. but it seems to happen when releasing the accelerator.

Ro55 - is your motor sorted now after all your problems?

 

[Ro55]

No im still chucking silly money at it.

Could it be the fan?
I dont want to say the G or C words.
whats the mileage?
not heard alot of gearbox problems on these so only assume there a good box?
Get your aux belt off and have a feel on the pulleys?
Whip off your turbo pipe and check for play.

 

[Ovid]

sounds like turbo is it diesel or petrol

 

[norris_309]

It's a diesel avf engine.
I did wonder about turbo as well, it drives fine and the noise is more prominent in 2nd gear below 2k revs you can hear it in first but 3rd+ don't seem to notice, but then there is more engine and wind noise etc..
If revving above 2k it doesn't seem to do it?..
The car is currently on 129k miles
Taking off aux belts & turbo pipes might be a bit beyond me... brakes discs & pads are my limit!! lol
I need to grow some balls though as this car & my golf both need a new thermostat!! ...

perhaps i'm listening too closely, the mrs laughs at me for 'looking for problems' but i'm sure it's not always done it.

 

[Ovid]

Maybe sticky vanes in turbo

 

[norris_309]

I'm getting scared now.
I'll look into this sticky vanes issue, see if it sounds similar.

 

[norris_309]

Been driving around listening out for this nose still.... it's intermittent.
If it was a clutch release bearing, would that happen when releasing the accelerator & not pressing the clutch pedal?
as I thought that's what it may be before I realised it happens when releasing the accelerator rather than pressing the clutch (the 2 obviously go hand in hand) but I've been driving around with no radio on listening lol, sometimes slowing down when the revs drop & easing off throttle you'll hear the noise..
Confused..

I just thought to be release bearing it'd have to happen when using the clutch? or am I wrong?

 

[Ro55]

See if you can get a video or something?

 

[norris_309]

to be honest, I don't think you'd be able to hear it on a video.
It's one of those noises that if you weren't told about it you'd probably not hear it. But once you knew... you keep hearing it now.
It's clearly not right but hope it's nothing serious, I'll have to leave it for now & see how it goes.

I di have a habit of listening a bit too much lol.. so the mrs tells me anyway.

 

[frankc]

I wonder if it has anything to do with the boost control system as when you release the throttle to either change gear or decelerate then the turbo vanes are closed by the solenoid. Might be worth manually moving the lever by hand with the engine off (and cold) just to rule out any rough movement that could cause the grinding you describe?

 

[norris_309]

that would make sense, is that something that can be seen/moved without taking bits apart.
Excuse my lack of knowledge... I've not heard of boost control system.. or where i'll find a lever to move.

 

[Ro55]

Id be checking the turbo

 

[frankc]

Yes the solenoid for the variable vane mechanism is vacuum operated and attached to the side of the turbo.

Yours is 1.9 isn't it? Turbo is down the driver's side, you'll probably have to take the engine cover off for better access. The lever is spring loaded and can be stiff but should move smoothly by hand.

 

[norris_309]

Nice one, yeah it is 1.9 avf engine.
I'll take a look on the weekend.
Need to get the engine cover off to see where the thermostat is as that needs changing. Gotta decide whether to do it myself of just book it in!
Sounds easy enough but things never seem to go as well as intended!

 

[frankc]

Thermostat is easy enough on the 1.9. Always a good idea to test the new thermostat before fitting by putting it in a pan of water with the old one and bring to the boil & make sure they both open & close at the same time - saves you the effort of replacing if you find after that you've bought a duff! Also get a replacement seal to fit with the new stat as the old one will probably fall to bits on removal.

 

[norris_309]

Thanks for that.
Sounds like good advice... is it common to get a duff thermostat then?.. the more you read about them the more it sounds hit & miss whether you get a good one?
I'd be getting a genuine one, does that not come with the new seal?

 

[Ro55]

seal id bought seperate,tight gits audi lol

 

[norris_309]

I'm glad you told me that.. would have probably had to make a second trip!!...
A bit off topic but..
I take it you just drained some of the coolant from a bottom drain plug? (i'm guessing there is one, not had a look yet) and then just swapped the thermostat over & then topped the coolant back up?
I take it the coolant doesn't need totally draining, so just need to buy one lot of coolant & dilute it however it says to.
I need to do my golf too... ****** cars
(I've never changed a thermostat, & I've got a slight phobia of removing parts where fluid is likely to pour from!! lol

 

[Ovid]

where in the uk are you , maybe someone nearby could lend a hand ?

 

[frankc]

is it common to get a duff thermostat then?

Wouldn't say entirely unknown but can happen, and of course you'll only find out about it after you've gone to the effort of changing it & filling with new coolant & taken it for a good drive.

Genuine is a good shout, tend to be of higher quality.

Need a PD 1.9 owner to confirm the position of the thermostat on the engine as my 1.9 was an older B5 and the stat was quite low on the block thus I just drained the entire system and refilled with new fluid. It's a good opportunity to replace with new coolant as it should be done every 2 years anyway.

As Ovid suggests, might be someone local to you who wouldn't mind giving you some pointers, good learning experience and a chance to save a few quid.

 

[Ro55]

I just undone, let fluid drain into a bowl. once stopped ,clean surfaces ect.
fit parts,measured rougly how much was lost,filled up ...run it bleed ect, good run,
up to temp.check level all the time.leave over night,check in am and top up if needed.

loads of ways to do it.what ever you find easy.

 

[norris_309]

Cheers for the helpful advice, don't think i'd bother someone on here to spend their time with me.
I'll see if the old man fancies giving it a go, he has more level drive space than me!..
Ro55 - you drained all of the coolant then did you & then put new in? think my coolant was changed less than a year ago during a cambelt change. How much coolant do you need to buy to fill back up?

As for the original issue, I've found this link today
http://www.audi-sport.net/xf/thread...throttle-release-from-a4-tdi-sport-130.13553/

Initially it made me feel better about it, as it seems to be "normal", that was until the final post!!.. camelt tensioners falling apart?...
I did have the cambelt replaced last year, which was done at a VW/Audi specialist with genuine parts, and I've used them to do the belts on my golf too with no problems.

 

[norris_309]

Just bumping this thread I made a while ago.
The Mrs normally drives the Audi & I'd all but forgotten about it, but recently I've been taking it to work & the odd whirring noise is getting on my nerves...
So I've been back on this internet looking around for an example noise & came across a YouTube vid with the exact same noise as mine

The noise happens in the vid when the let off the throttle, you hear a whistle then there's the spinning/wheezing/ sort of noise....
Any one know what this noise is? it's been going on for a long time now, I originally posted nearly a year ago!!... it doesn't appear to have got worse as far as I can tell.

 

[Peaky]

Just bumping this thread I made a while ago.
The Mrs normally drives the Audi & I'd all but forgotten about it, but recently I've been taking it to work & the odd whirring noise is getting on my nerves...
So I've been back on this internet looking around for an example noise & came across a YouTube vid with the exact same noise as mine

The noise happens in the vid when the let off the throttle, you hear a whistle then there's the spinning/wheezing/ sort of noise....
Any one know what this noise is? it's been going on for a long time now, I originally posted nearly a year ago!!... it doesn't appear to have got worse as far as I can tell.

Old thread I know but did you ever find the problem?

 

[norris_309]

No not really, i've still got the car and it still does it. I'm just guessing it's the actuator on the turbo or the turbo vanes being a little clogged as it has gone into limp mode on occasion (some turbo cleaner & a bit of revving seems to sort that temporarily)
Sorry i've not got a definitive answer for you but looking back at this thread it was on 129k miles back then.. it's on 180k now! (touch wood it'll keep going)

 

[Arslan46]

Hi,

I've recently been noticing this odd noise, it's like a spinning/grinding sound. Kind of like the noise you hear when your brake pads are worn out & rubbing the discs (it's not that by the way!) it seems to be coming from the drivers side front.

At first I thought it was something to do with the clutch as it seems to happen when pushing the clutch in to change gear & you mainly hear it going from first to second.
I've since realised it actually may happen when you let the accelerator off (so same time as pressing clutch)
It's not a loud noise at all but i'm sure it never used to do it.

Driving to work today I kept letting the accelerator off when in first & second & you could hear it then regardless of pressing the clutch. and it seems to change in how bad/loud it is, sometimes not actually making the noise??
I'm confused?? any ideas... anyone else have this

Same exact problem with my audi a6 16reg. Did you manage to find the problem mate please let us know. Thanks

 

[norris_309]

I'm several years on & it still does it! probably worse now than back when i initially posted this.
As for the source, I'm pretty certain it's the turbo, I get limp mode a bit too often now a days (but the car doesn't get used much these days)
So, I suspect the vanes are sticking/clogged so could do with a new turbo (worth it on a 2004 180k mile car?) when it does go into limp mode the noise isn't there, so must be the turbo.
I'd like to think you weren't having the problem on a 16 plate car, but i guess it depends on the way the car is used maybe? mine seems worse now i work from home & it doesn't get driven as a diesel should be.