Been away for a while which is good no issues of late other than our 2004 a3 105bhp 1.9tdi is very cattery noisy when ticking over around 800rpm, when you take the revs up very slightly to 1000rpm its a lot quieter.  Anyone any ideas what it could be, i have hunted around the engine bay and cant find anything loose so at a loss as to what it could be.

Cheers

Mark

No it doesn't improve it only quietens down when you slightly lift the revs.

 Hard to know without seeing the car, maybe an alternator clutch, or the flywheel? Has it got worse over time?

No it hasnt gotten any worse over time.  Its always done it its like something is vibrating i would say, it was just in case there were any common causes for it.  Car has had a new alternator and new clutch and flywheel, it made the noise prior to these being fitted.

Cheers

 MIght be worth getting the oil pressure checked. Could the engine be running low on oil at low revs and then when revved abit the oil pump raises the pressure and the noise goes?

 Yep just the springs. Ive seen the springs in uk on some tuning websites for around 140ish sterling. So if that was 200 over here, and then maybe they charging a good bit for fitting?

stevee:

 MIght be worth getting the oil pressure checked. Could the engine be running low on oil at low revs and then when revved abit the oil pump raises the pressure and the noise goes?

Is there anyway you can adjust the idle speed?  Was thinking could raise it from being750-800rpm to 1000rpm that would cure it.

How difficult is it to get the oil pressure checked, would the oil pressure light not come on if it was running low? 

 You can raise the idle speed alright on VCDS - vagcom. Whether itll stay at that or revert to the standard again im not sure. The oil pressure light should come on alright. But maybe the pressure is just about ok where the sensor is and then its being lost. Either way its worth finding the solution,.

How bad of a noise is it?

Its not too bad, I will record it and post it up tonight so you can hear it.

 Do. And theres a good few here at might take a listen and have a idea, Rusty is a good man on Diesels

Here is a clip of the noise she is making, cheers

 Does that noise get worse if, while stationary you turn the steering side to side?

Stevee yes it does get ever so slightly worse if you turn the wheel or put pressure on the steering wheel, whats the thoughts on it?

It could be a few things as its extra stress on the engine, but my guess is that its the clutch on the alternator. Its a very common problem and its at its worst when you "dry Steer". Its a horrible vibration noise.

Replaced the alternator not long ago thats not to say it could have failed already probably 3K miles, would it be worth taking the aux belt off and running the car to see if the noise goes away?

Cheers for your thoughts.

It could be one of the other pulleys that is on the way out maybe.

Is there any easy way to narrow it down?  Any tips on checking them out and telling if one is gone?

Well took the aux belt off and she runs nice and quiet just as it should.  So its tensioner alternator or air con compressor.  The alternator was changed about 6 months ago and the old unit that came off seemed to keep running if you spun the pulley and then stopped the pulley dead, this one doesnt have the freewheel action could this be a problem?  Other than that i was thinking might be worth changing the tensioner as they are only around £30. 

Any thoughts on this?

Trying to locate an aux dive belt tensioner for the engine its the BKC engine and am struggling to find one, anyone any ideas where i can get one other than Audi?

Cheers

Got one here:

http://cgi.ebay.co.uk/2005-2008-SKODA-OCTAVIA-A5-2-0TDi-ALTERNATOR-TENSIONER-/320648839391?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4aa82900df

Decent enough price for geniune part, so will so how it goes once fitted.

Cheer for your help as usual Stevee, much appretiated..

Well new genuine tensioner fitted today as well as oil change and she is still making the noise.  So no noise with belt off so leaves the alternator or air con pump the joys, at least we now have a new tensioner fitted..

Annoying, but if its any comfort they are a common wear point.

Is there any play in the other pulleys?

Nope all the other pulleys seem fine, with the new tensioner she doesnt make as much noise when ideling but when you apply throttle it appears around the 950rpm mark now and only for a couple of hundred revs.  Think i am just going to have to live with it, dont want to shell out on a new alternator when it might not be that.  Could the crankshaft cause the noise??

 Mechanics have a listening device, like the doc would use to hear your breathing, to put on a pulley to listen to the bearings. Might not be too expensive.

Cheers Stevee, will maybe pop in past a local garage and see if they can take a look.  What would be your thoughts likely either the air con or alternator, the alternator i bought was off ebay and was second hand so maybe its suspect.  The old one made a hell of a noise and if you revved her past 3K it would illuminate the charge light on the dash.

Nope the noise doesnt change with the air con on or off.

 So id bet the alternator clutch

Cheers Stevee, is that something that could be changed without having to get a new alternator or is it easier to just swap the alternator??

Could i just change the alternator clutch or am i best to opt for another alternator?

 Yep clutch alone can be changed

Is it easy enough to swap over?

Any ideas where i can get one?

What sort of sound do they make when they are gone?  Should these alternators have the freewheel action you know when you spin it in your hand and stop and the spindle should keep spinning?

Cheers

 Hmm not sure where is best place to buy. Might be worth asking GSF car parts?

Id say its going to be that over the aircon alright. I'll just check where they can be bought

Maybe its the fact that its not freewheeling that the problem is, if the pully on the alternator is jammed and not allowing it to freewheel then maybe thats causing the tensioner to jump around as much as it does.  I think i will have a go at trying to free it off, or maybe its the case it shouldnt freewheel whats the thoughts?

 Yep exactly. It should free wheel.

Do you reckon that since its not freewheeling then this could cause the noise and also the tensioner to be moving around so much?

 If it was binding it would cause the tensioner to chatter alright.