Knocking
 

Hi everyone,I am a new guy here.i have Audi tt 1.8t Quattro 2001 and this is what is happening:engine have sound like a diesel actually is knocking.reading a lot of posts online and visiting few services everything is about sump or tensioner.to clear sump "filter" cost about 300$ and tensioner fix is about 800$.so I would rather like that is sump and problem with the oil pressure.but things are not so clear and nobody knows what exactly problem is.
Weird thing is that engine never knocks before its on work temperature and it's not happening all the time just sometimes.when I add little bit rpm-s it stops!!
I have 135 000 miles on it and everything runs perfect except that noice.did anyone had and solve this issue and what are solutions for fixing it?
Btw cluster is not working so I can not count on signal for oil on my dash board.

Thanks in advance, cheers!