I have a 2003 L322 4.4 V8. It ran ok but with what can only be described as a slight Vanos rattle.
The car previously had timing chain failure before I bought it and it had been rebuilt. The car suddenly decided not to start and sounds like it’s lost compression. It didn’t cut out. It wasn’t down on power, it didn’t death rattle. It just would t start. On investigation I found the chain tensioner to be pretty useless so I have surmised that it’s probably suffered a slip of the timing. I have access to the tools to lock her up but can this be done and the timing moved bu just removing the cam covers. I don’t want to strip it down where it is currently parked.

Any help greatly appreciated

Could it be sticking valves? Just a thought. Especially if the car had been sitting for long.
I've seen a freelander running fine in the evening and early morning refusing to start, with loss of compression. Turned out some valves were sticking