So after successfully doing the primary and secondary chains on my xjr I decided to buy a xj8 with a bad trans from my uncle. 700 with the extra trans..why not right? Everything went smooth, shifted nice engine smooth no noise.. than I got a rattle from the engine lol. This happened after I redlined it... Around 2k rpm and up revving in neutral and slightly hear it from the cabin while accelerating. Changed the oil and found nothing in the old oil. Pulled off the valve covers and while both upper chains tight, the passenger side chain was riding on the metal and the plastic had fallen off. Great I thought and changed out the tensioner with an old one I had in good shape from my xjr. Same noise afterwards. On a 10 mile drive home the sound got worse. Clacking at idle all through the rpms...

All the chains are tight and cams in time.. Could it still be chains hitting something? Or maybe rod knock since I did push it on oil that was who knows how old and on the low part of the dipstick? Last thing I want to do is spend 400 dollars on new upper and lower chains tensioners and guides plus all the labor and the sound still be there... Thanks for reading my rambling.. Any advice would be great

Sounds similiar to this

 

I do not like that sound. Just for kicks, can you take the serpantine belt off and see if it changes?

 

Tried that with no luck.. I think I'm going to cut my losses...

 

Quick and dirty test for rod knock : remove the plugs, insert a metal rod down the hole until it touches the top of the piston. Rotate the crankshaft pulley back and forth, through top dead centre. Feel for non-smooth movement of the piston, which indicates a failed big or small end bearing.