ok i have a B6 03 A4. 1.8t with 85k on it. on startup it makes a loud rattleing noise, now i have researched this and it seems to be possilble camshaft adjuster building pressure. so ok that is fine. but the noise is way loud on startup, and then quiets down. but doesnt go away. i thought it might be a valve ticking or something but when i rev it up past 1k rpms it goes away. the noise almost sounds like my car is a diesel. and its pretty loud in and out of the car. when you rev up the car and thenoise goes away and the car drops back to idle. ittakes a split second for the noise to settle back in.maybe something loose?! some days, maybe once or twice a month i will be driving and come toa stop and notice the noise is gone![:-]but sure enough itcomes back.i have had the car for about 12k. changed it religiously with mobil 1 synthetic every 3k. and i had south bend clutch with a lightened flywheel, that baby rattled pretty good at idle, with the clutch out(normal). it weant out and i put in the oem clutch ( didnt know i had the southbend until i pulled it out).kinda sounds like that. but an oem clutch shouldnt rattle. and like i said sometimes it goesaway.it is gettin old, everytime i come to a stoplight or am sitting in traffic it sounds like a diesel.and it does it with the AC both on and off. so rule that out. ANY ideas please help. clutch? valve? loose?i am getting worried. thank you

 

any rattle of this magnitude cant be good and could be something loose ( at idle only ) is a posing problem, try to pinpoint where the noise is coming from like top end/bottom end/clutch and gearbox area ( when at idle and the noise is evident press the clutch peddle in and see if it goes away ) that would point to the clutch as being the problem

 

ok well i read your reply (thank you). and i decided to gout and fire up the car to better diagnose the area where it was coming from. sure as sh** no noise. i reved it up to 5 and held it for a second and let it fall back to idle. there is a noise, but not of the magnitude it was at all before. so after i drive it for a while this afternoon i will see how it is going. there are in fact some small noises. ticking and such. i found 2. both not audible until hood was opened.
1. underneath the vavle cover back by the firewall (cam chain?)
2. the little black box next to the intake system. made quite a bit of noise. right up by the grill on the far left. i put my ear to it and it is definately ticking.... normal??

 

cam chain tensioner might be going

 

ive seen that cam chain tensioners arent all that harmful. just noisy. so if i pull of my vavle cover will it be pretty easy to feel if my cam chain is loose?

 

I've got a 97 with 130,000. It was noisey when I got it a couple months ago. Heat sheilds on cats rattled and the cats were also clogged. Replacing them took care of most the noise but still had rattles under hood. Just did timing belt change and replaced water pump, tensioner roller and timing belt roller. Its real quiet now but can't say for sure what was making all the racket.

 

thanks for your help. i dont think i have a sludge problem. but that would explain it. i know my cat cant be plugged cus i have a brand new test pipe. 02 sensors are fine, just reading the same air. it threw a cel when i put on tha test pipe. but performance wise the cars fine. i just drove it about 15 miles to lunch and back. no rattling. but i swear its just waiting to come back. my car is trying to make me look like an idiot[:@]thnkx for your help. it sounds like cam chain almost 80%. what is that little black box next to my intake ticking?! looking at the motor it is on the left front. semi-loud

 

That's the EVAP purge valve. It's normal for it to make a ticking sound.