Following a 10km / 1hr traffic jam yesterday, during which I thought the clutch was going to give up the ghost (severe juddering when starting from a standstill), my 2007 tfsi vrs has developed a tapping / knocking noise in the engine bay. Unfortunately it's quite loud, can be heard from the cabin. I checked the oil level, it's more than half, plus I've done the change about 2k ago so that should be fine. 

 

Trying to isolate where the noise is coming from, it seems it's coming from near the cambelt somewhere. Can't really say if it's from the top or the bottom of the engine, maybe more like midway through. I started the car this morning and the noise is there from cold to warm (i.e. all the time) and the tapping rises and falls with the revs. I am dreading a bit that it could be the cam chain / tensioner, but that's on the opposite side of the engine and the noise doesn't really seem to be coming from there. As far as the cambelt goes, it was done approx 80.000km / 50.000 miles / 3 years ago, together with the water pump.

 

Any idea what it might be?

Edited 8 May, 201610 yr by jmf

Tinkered with it some more and I *think* the sound is coming from the cam belt tensioner. Unfortunately I don't have a stethoscope or a really long screwdriver to listen to it, however just holding a screwdriver onto it I can kind of feel the vibrations in my hand in time with the noise which is a repeating "tap-tap-tap" at idle with maybe half a second pause in between. I didn't know the tensioner can actually make such noise and of course I'm not 100% it is the cause. 

 

Is there any surefire way to diagnose it short of replacing it? Also, should I minimize the driving until I get it replaced?

 

Btw, is the tensioner supposed to be vibrating? By this I mean that it's not holding perfectly still, but it's rather moving towards the back and front of the car...like, I can see the pin on its right moving.

Edited 8 May, 201610 yr by jmf

^ cam belt tensioner = serpentine belt tensioner

if you think its a tensioner then I would advise against driving the car until you can be sure. it could fail suddenly and leave you stranded.

It was the tensioner, was replaced and the sound is gone. Additionally it looks like the serpentine belt was never changed  :peek:  (car has 160k km) and had already the top layer broken in two places, matter of days probably before it went completely.