X5 engine knocking, ticking, slapping noise - help!

[X5-mark]

Hi
I have a 2002 x5 3.0 petrol (with LPG also), recently it's developed a strange noise. It started as a metallic type chattering a few weeks ago but we picked it up from the airport after 10 days away and it seemed a bit worse, this morning it progressed to a knock? type noise, it was bad so i took a video and left the car on the drive!

Not sure if its possible a failed pulley could make this noise? The alternator was replaced a couple of months ago.

http://www.youtube.com/watch?v=uBiDn3D8 ... ata_player

If anyone has any ideas please let me know.
Thanks

[IanP]

Vanos (if it has one), cam chain tensioner or sticking hydraulic tappet. Does not sound bottom endy (is that a word?)

[X5-mark]

Thanks for the reply Ian, would all of your suggestions increase the speed of the knock with increase in revs? I forgot to mention the computer has not recorded a fault...

[IanP]

The noise should increase with revs with all of the things I mentioned, it does sound half engine speed which suggests something around the cylinder head. It is really difficult to pinpoint a noise without seeing the car, so I think it would be better to get it to a garage before it becomes more expensive to repair

[shadrack]

Where u at? Maybe someone on here could recommend a good indy that's local to you to diagnose it honestly