Hey guys, I was looking for some help on here so hopefully some one can.

I have a 2000 Audi A4 1.8t Quattro ATW that I've had for 7 years now. It's been a great car and nothing really has gone wrong with it far from maintenance things. It's always been fed premium fuel and it's always had a full synthetic oil change every 4,000 (though I have always used mobile 1 10w40 which I read isn't a wise choice),

The problem I have now is that the car has developed this extremely loud knocking/tapping sound out of the blue. (no, it's not the valve on my air box or the injectors)

This sounds like it's directly over cylinder one at the front of the engine and it's pretty obvious, you can hear it with the hood down. Forums say that this sound is the cam chain tensioner, but how if the noise is coming from the opposite side? The car runs like it normally does, there is no loss of power, and no change in temp. so I don't think it's a timing issue.

The noise is only at idle. If I tap the gas the noise will speed up slightly with the rpms but then disappear. Another weird thing is that I've let the tapping continue during idle until the car reached operating temperature and the tapping will remain BUT if i drive the car from one place to another for more then 2-3 miles the tapping is gone and the car idles normally.

That's about all i have left to explain to you guys. I really appreciate any help!

 

Could be a sunken lifter. How are you sure it's not valvetrain noise?

 

I'm not sure to be honest. The tapping is slow so I have reason to believe only one item is at fault. A friend told me it could be a collapsed lifter as well- any idea how to test/fix this theory?