Land Rover Repair: engine knock noise, piston slap, engine knock

Question
Hi, I bought a 2003 LR Disco II not too long ago. I took it to my friend's shop and did an oil change, air filter and spark plugs. Three days later, I started hearing a loud knocking from the engine. It only happens when the engine warms up. Sometimes it disappears for a short time but it comes back.  The knocking is not in fast intervals.  The truck runs fine, and none of the lights are on in the dash.  I have tried all sorts of additives but it has not helped.  It's been two months and no one can tell me exactly what is causing the noise. If you have any suggestions, I would appreciate it. Thanks!

Answer
Hi AJ,

could be slipped cylinder liner.  Could also be main bearing, piston slap and maybe heat shield is loose above cats.  

Make sure to watch your oil pressure.  The '03's have problems with oil pump and how it seats with engine, so this problem could be the result of this design flaw.  

Best of luck,

JohnMc