VW GOLF MK5 GT 2.0 TDI - Engine rattling sound idle, pully tensioner? - K21000

This sound started a couple of days ago and is only noticeable when idle. It comes and goes, but is mostly there and it worries me a little. The car is meticulously serviced, has relatively low mileage for it’s age (70k) and runs perfectly. Cambelt is also nowhere near due for replacement. I think this short vid clip I made may point out where the sound is coming from. The alloy housing behind the alternator pully seems to be moving in time to the noise. Is this something to worry about? I have spoke to a local garage and they seem unsure where the noise is coming from, so no help. I personally think that it is coming from where I have pointed out. Any ideas and advice are much appreciated.

https://www.amazon.co.uk/clouddrive/share/4cOUDJXMsvxLvJndV0BMUmGCALqunCzuKSnbE0nENqg?v=grid&ref_=cd_ph_share_link_copy


VW GOLF MK5 GT 2.0 TDI - Engine rattling sound idle, pully tensioner? - kiss (keep it simple)

You could well be right. Time to get the drive belt and tensioner changed.

VW GOLF MK5 GT 2.0 TDI - Engine rattling sound idle, pully tensioner? - elekie&a/c doctor

Erratic tensioner movement can be caused by a faulty alternator pulley.These are the "overrun" clutch type.

VW GOLF MK5 GT 2.0 TDI - Engine rattling sound idle, pully tensioner? - Steveieb

elekie doc is the absolute expert on this. but I had a similar problem on my AWX engine where the engine shut down and it was the alternator clutch.

These can be replaced for about £90 but many garages change the alernator whole which costs much much more.

VW GOLF MK5 GT 2.0 TDI - Engine rattling sound idle, pully tensioner? - K21000

I really don't want to start guessing and throwing money at it randomly. I have had suggestions on various forums from flywheel failure to new alternator, drive belts, pulleys, bearings etc. I was hoping the video would be conclusive and someone would have had this problem and known what it was. A local mechanic was unsure. I may have to bite the bullet on this one and take it to a VW dealership.

VW GOLF MK5 GT 2.0 TDI - Engine rattling sound idle, pully tensioner? - bathtub tom

You could remove the belt and see if the noise goes.