Hi, I have a 99 A4 1.8t (manual) with 120K that suddenly sounds like a diesel. The loud click/knock seems to be comming from the top end and occurs at low RPM (< 2200 RPM). Above 2200 the noise goes away entirely and the car sounds just like it used to. I replaced the cam chain tensioner but no luck... same noise. Could this be a lifter? I was also tinking a clogged oil pickup as there was a decent amount of buildup on the screen of the chain tensioner when I replaced it. Is there an easy test for either? Thanks for any help!

I checked the oil pressure (and if anthing it's a little high) so I'm thinking it's not a clogged pick-up. This has to be a lifter, no? I removed the valve cover and none of the lifters were mushy though. Any thoughts? Any help/suggestions would really be appreciated.

I've had similar problem.
i used to get a clicking sound like diesels when the engine starts, then after couple mins when the engine is warm it goes away.
So if this is what is toy ou then your problem is: Compensators are clogged up.

Change your engine oils and within couple weeks your car should stop that clicking sound (it will clean up). If it won't stop, then your compensators are already broken and needs to be changed, though it's not serious if you will not change them, but that clicking sound seems to be annoying.

i have 2010 A4 1.8T runs only 500km and there is a sound like a diesel engine coming from the back of engine,i wonder if its normal or some thing wrong there.