I just bought a 93 Range Rover Classic LWB that had a headgasket problem confirmed by the previous owner. After he discovered the problem, slight overheating and combustion gas in the cooling system, he immediately parked gthe vehicle, changed the oil, and sold it to me. I heard it run briefly before removing the passenger side head and replacing the gasket. It was obvious by the heavy sludge accumulation on the head thatb the engine had not been cared for very well. With 189K it was due for the boneyard anyway. After replacing the headgasket, plugs, and fluids, I started it up and heard a very pronounced knock coming from the center of the engine. I shut it down, removed the valve cover and inspected the rockers and pushrods, expecting to find one that had not seated properly, but found nothing obvious, all lifters were moving freely, all pushrods going up & down, I could not locate the source of the knock. After a thorough inspection of everything I had touched I decided ti abandon the sludged out 4.2L and purchased a nive clean low milage 3.9L from a 95 Disco I. I spent all day removing the old engine and tomorrow will clean and install the new one. If anyone reading this has a theory on what could have caused the sudden knock I'd lovr to hear it. Thanks

 

How long did you let the engine run for while it knocked? A Jag motor that I rebuilt knocked for about 5 to 10 seconds before the oil pressure built up and it went smooth. Tt sat for almost a year though. It started to knock again about 3k miles later and had a low oil pressure warning. It turned out that there was a lot of junk in the oil pickup catch screen.

 

Are all exhaust manifold bolts and gaskets good? They can some times fool you into thinking you have a knock.

What about the inlet manifold bolts and gasket. Not sure they would have the same effect though.

NKG