Hi all.
Replaced the left belt idler 6304ZZ bearing, it was not the problem. Same knocking noise with compressor engaged or when AC is off. Would that mean the clutch bearing ? The compressor pulley turns smooth by hand with the belt off. What else behind/under the compressor can knock ?
Unless better suggestions, will replace the belt with a shorter one to bypass the compressor and confirm that is the problem by running without it. Stethoscope is loud at idler shaft and at compressor shaft.
Should I try a few moments with no belt at all ?

 

You can run with no belt, I have. 10-15 seconds on a cold motor won't matter at all, and will give you your answer.

Edit: Well, will give you one answer...

 

Thanks. Without the belt; no knocking noises. So not coming from inside the engine !
Found the steering pump flange on its shaft shifted inwards 2mm. Pryed outward, no more knocking