This is more common with the 4.6 than any other Rover engine.
Under Fords ownership quailty control was not job #1.

 

What about the P-38 Range Rover 4.6L motor, isnt that a good engine, and would it swap out without setting off all my dash warning lights??

 

The 4.6 from the P-38 is a good engine, but you need to make sure that you get the Bosch engine and not the GEMS engine.
If you get the GEMS it will bolt up but you will need the GEMS ECU.

http://www.roverparts.com/TechTips/boschvsgems.cfm

 

Hi all, I am researching swapping out the motor in my 2001 DII. Is a 4.6 an option; will it bolt in the same and is it compatible with ECU. Would I still use everything from the intake up from my original 4.0? Also are the heads different on a 4.6 and a 4.0; in other words will a 4.6 short block work with my 4.0 parts from heads up. Any other options, ideas, options and advise are very welcome; I am in the early stages of researching a motor swap. One more question; are these blocks repairable once the sleeves/blocks are cracked or just throw away?

 

Yeah it will bolt right on, the heads are the same. There are minor differences like 2003/2004 did not have engine oil coolers and pre-2003 did have them. Also be aware of SAI and non-SAI engines, the heads for SAI have 2 ports each and the non-SAI do not have those ports.
As for repairing blocks it depends on what is wrong. Slipped liners can be replaced at about $200 per cylinder, I'm guessing a cracked block is a boat anchor.