Hello all! Just a general opinion question. I just got thru reading today's post about changing big end and main shells, my Disco is almost sorted, but nagging me with a very slight knock from engine area when I set off. And I mean slight, with stereo on minimum volume it's imperceptible. There is no knock, tick, ping, bleep, or creep when engine is idling, and I've stethoscoped the engine at idle with no knock. It only comes on with load. I'm really just trying to talk myself into changing all the shells while I pull the front cover, so does it meet the criteria for worn mains? My oil pressure is on the lower side of normal with vr1 20w-50 and Mann monster filter. Thanks in advance for any insight!

 

If you will already have the front cover off, then the oil pan must be lowered(unless the 3 timing cover studs were already replaced with bolts).
You can remove a rod or main cap(2 bolts) and visually inspect the lower bearing half.
It will be easy to tell if they are good or bad, and if you're unsure, you can google images to check them by.
But, if you have a slight knock, and given that most of these engines are higher mileage by now, chances are they all have enough wear to justify replacing them, considering that they are cheap, and not that hard to replace.