I did a search on this and it seems that there are many threads describing basically the same thing. I just wanted a direct opinion on my car. I understand that these engines have a normal tick noise and I'm hoping that is the case with mine. The car's performance doesn't feel reduced, seems to be running normal.

It sounds a little exaggerated in the video. Oil level is good and the car is warmed up.

1998 Audi A4 1.8t Quattro Engine Ticking - YouTube

 

I put off the noise since nobody replied to this thread when I posted it a while back but now it's worrying me again. Could someone help shed some light on this?

 

now im no expert on this at all, but could it be a check valve? i know one of mine makes a lot of noise, the one right behind/above the stock airbox... just a thought

 

Thanks for the response, I'll look at it in a bit.

What exactly is the purpose of the check valve, I know it's part of the vacuum system. How do I know if it needs to be replaced, just if it is leaking?