The timing
Belt was replaced though...on a cold start the sound kicks in after 30 seconds...the sound is in sync when I rev on neutral...

 

You don't think it might be a lifter issue? Cam chain? thats making the noise.

 

i dunno.. it sounds like something outside the engine.. but the sound quality's not great.. i've heard similar sounds from mine, it was all from belt driven bearings going bad on various parts. i did my timing belt and **** 2 years ago, and the water pump seized up less than a year later. almost took out my belt with it. i barely scraped by on that one it looked like, the pump was toast. i really wouldn't drive the car until i figured it out. i'd definitely get in there and see whats going on.

if you really can't figure it out, look for a german specific shop. luckily i have one a few miles away.. once in a blue moon i take it there for an oil change and a "hey, btw can you look at this" diagnosis so i can do it myself lol

 

I think I found the problem...one of the bearings on the timing belt is shot? Let me know here's a video li k to my car.


Audi a4 b5 timing belt issue? - YouTube

 

I would say cam chain tensioner. Wouldn't build total tension until the engine has been running for a few (30) secs.

 

we found the problem...the water pump was moved forward causing one of the timing belt pulleys to wiggle around and scrap against metal leaving metal debri... Which cause the noise you hear on the videos I posted.

 

You are so lucky it didn't snap the belt while it was running

 

Lucky

 

lol told you not to drive it

 

I didn't drive it...it spent a night at the shop...I'm $400 less from the waterpump + labor