For those that missed it, here's the video of the knock I'm chasing:

 

Sounds just like my '02.

 

The random knock may be just a worn thrust bearing??
How much end float on the crank is there?

Man, you are a good mechanic from what I can see.
I have only done heads.

Oil pump, chain.. seems a lot worse than simple heads.

 

Here's the upper and lower mains:



They don't look too bad so I went ahead and pinned the liner in cylinder 1 anyway:







And painted the exhaust manifolds...

 

Those bearings look great IMO - certainly not the cause of any harm and shows that oil pressure must have been good.
Why not pin all the liners that you can get to easily? If the problem hasn't happened yet, it is possibly only a matter of time...

 

After pinning the one liner and replacing all the bearings she's drives great and my big knock is gone. I still have a much, much less, noticeable knock only when I pull the wire to plug number one. Which is odd! But, since it's not there with the wire on I'm not too worried about it as I plan to do the camshaft and tappets next..

As for pinning the rest of the liners, doing just one was a true test of patience! It was my understanding that a liner can slip (permanently) when the engine overheats past 230º and destroys the bonding agent holding it in place? Which is what happened to mine when the head gaskets went. Now I maintain a pretty steady temp average of 185º with the hot climate t stat and stayed glued to the ultra gauge. Are you saying I have to worry about other liners coming lose even if my engine doesn't overheat again?

 

"It was my understanding that a liner can slip (permanently) when the engine overheats past 230º and destroys the bonding agent holding it in place? Which is what happened to mine when the head gaskets went."

No, no, there is no "bonding agent" holding liners in place--how do such fairy tales get started? The liners are installed when they are in a cold state, with the aluminum engine block held at a high temperarure, so that when it all cools down, the liners are held by the fact of their changed dimensions slightly due to heated block, from when they were installed in hot block initially. When liners move, it is usually caused because the overheating causes minute cracks in aluminum walls behind liners, allowing a much more loose fit between liners and aluminum cylinder walls, so they move from piston friction moving them up/down. However, on later engines in the series, Rover had a shoulder cast into base of each cylinder bore, to butt each liner onto, so it is many times more unlikely that they will move, and they certainly can't move downward due to those shoulders.

 

Slipped Liners??? - Land Rover Forums : Land Rover and Range Rover Forum

 

Not to highjack here... This is a VERY informative thread, especially since I have the knock as well... I haven't pulled any plug wires, but I think that is my next step to try and determine where it is coming from (and of course the yard stick trick).

I clicked through to read the thread on LRO... reminded me a little of a thread on txrovers recently. A buddy bought an LR3 and was curious about the counterweights under the rear bumper. While at the dealer (to remain anonymous) he inquired.

"I was at Land Rover **** buying rubber mats for the LR3 today and went to look at a new Range Rover Sport Supercharged, it too has the counter weight. I asked the service advisers and they did not know what it was for. They asked a mechanic that was getting parts form the counter and he said those were counter weights so that if you are river crossing the vehicle engine weight will not pull you under."

I about spit out my beer when I read it, and then remembered why I never brought my truck there for service.

 

Well there was the problem. He should have asked the service manager, not the mechanic...