help please with engine noise

[makster1978]

hi i have a a3 1.8t aum the car runs fine but on cold start or being parked up a while after starting there is a tapping noise coming from somewhere near the bottom pulley under the alternator,the noise will fade out as the cars driven after a long drive to a point were some days it completely gos,performance isn't hindered even when the tapping is at its loudest,i am guessing possible noisy water pump but not sure,cambelt is due and am going to get the full kit but don't want to pay for this knowing i still might have this tapping noise.cheers

 

[makster1978]

we bump

 

[Ausjet_S3]

Sounds to me like a water pump bearing, though the fact it goes away after time has me a little confused as worn bearings tend to make noise all the time.

possibly too thin of a grade of oil for where you are? after sitting a while the oil would drain away from the main bearings and the cold would show that up, that noise causes more of a thunk than a tap though.

could even be the alternator? it works hardest when the car first starts to maintain battery voltage after cranking.

how fast/loud is the tapping?

 

[makster1978]

cheers for reply the noise is loudiest on start up then fades out during the drive,after 30 min of driving the noise pretty much vanishes to a point were i can still here it ever so slighty but thats just because i know its there,the speed of the noise mimicks the speed i am going,really hope it is the water pump but as you say if its the bearings youde think the noise would never go,ohh and just to mention i have a code crankshaft sensor no signal,oil is 5x40 fully synthetic recently serviced and noise was there before i did this