DISCO 2 V8 2003 Engine Noise

I seem to be plagued with issues accross both my landrovers at present maybe they have decide to take a xmas break !!

I just rebiult my 2003 V8, new pistons rings, bore hone, camshafts, rockers, lifters, all bearings water pump, oil pump all new hoses etc etc. All bearings were plastiguaged and a lot of time taken to do as close to perfect a rebiuld as possible.

I Ran the cam in for around 20 mins at 2500 approx rpm and engine ran fine with no noise using an SAE30 oil.

Changed oil filter oil to 10w40 ( with 1220 ppm zinc )as recommended for my conditions and am not sure when exactly the noise developed but at around 80km I noticed what I thought was a tappet noise only when the engine reaches around 94-100c ( this is about the max temperature based on ECU info from the inlet manifold temp sensor).

I thought perhaps it could be a valve lifter which as unlikley as it seemed I changed all the valve lifters anyway for another new set!!!

The noise still exists and if anything has worsened as I have now driven 400KM ( also now changed oil and went from Penrite to Castrol same spec but no change to noise) I have also have a significant oil leak from the front of the sump gasket ( yes new gaskets were used and appropriate sealants where specified) only once the engine is hot. Its been suggested crankcase is pressurizing same issue happens with oil filler cap removed not sure if that affects it as I dont understand the crankcase pressurisation possibility.

It has been suggested to me its a dropped liner but I had read on the Robinson US website that the V8's from 2003 on dont drop liners due to a manufacturing change in the block by Landrover to try an address the issue. One ssupposed local expert has told me what Roninson states is wrong and the blocks never changed in respect of location of the liners ..... Motor doesnt use coolant.

Have run engine removing one spark plug lead at a time to see if the noise changes but the noise stays the same.

The noise is definetly temp related as there is absolutly none on start up or until engine gets hot, noise getting worse the hotter the engine gets.

At the moment ther only option I seem to have is to remove and strip the engine and fit Darton sleeves.... note the people that did the heads and all the block work including a light skim on the block didnt find anything to indicate slipped liners. All they found was an unusually ovality on the central cylinders not on the thrust side but on the opposing cylinder walls which nowone could explain.

So far my wife tells me I have spent the princely sum of 10K pounds on this car ( yep I have spared no expense) and as much as I dont want to do another engine removal/strip etc I am too commited to this car not to get it 100%.

Appreciate all your help and ideas.

Later engines DO drop liners, however not in the same way as the earlier ones. They did change the block to add a ridge at the bottom of each bore so the liner is held in place at the bottom and the head holds it at the top. The liners are inserted and then the top deck machined flat however some were not pushed all the way home, which means they can sink. When manufactured properly this can't happen on a later block however it seem not all of them were. Mine had this on Number 4 and it did not use coolant. as it was only one cyl I have pinned it at the bottom and is fine now

Thanks Zaphod before the rebiuld there was no engine noise I think the only way to know is going to be to pull the engine and strip it down again. The engine now has better compression with new rings pistons etc maybe caused the liner to slip where it didnt before... will se if I can find some local folk with experince in pinning and if we can get it fown to what cylinder it is that may be the best and least expensive option.

Cheers