Just bought myself a 99 XK8 with rattle noise coming from upper chain tensioners, or so i thought.

When i lifted the cam covers i was surprised to see that the uppger tensioners had already been changed to the upgraded ones.
After listening to the engine, the noise seems to be coming from back of the engine, and it sounds the most under the car close to the turbine.
What could it be then?
is it a rod knock? A bad cathalytic converter? A broken valve?

Tried to film to small movies with sound:
Thankful for help

 

This one comes from above and below the engine and gets worse when put it in gear, but goes away after a few min. when the engine warms.
Mechanic says it piston slap.
Unknown Knock? Video by guzzisvt | Photobucket


Now this one is lower and upper timing chains. $3,300 fixed it.
Timing Chain Video by guzzisvt | Photobucket

 

You say you thought it was a tensioner I would use a stethoscope and try to pin down the location of the noise it could be a VVT. If it is not coming from the valve cover location start the car put it in gear and with your foot on the brake do a slight acceleration for a moment or two and see if the noise gets louder. This is an old school way of identifying a wrist pin or bearing problem. If the noise is from the valve cover area (VVT) change the oil and filter and see if that clears it up. To test the valves you will need to do a compression test on each cylinder. Remember the noises resonate and could put you in the wrong direction.

 

Just had a iCarsoft 930 hooked up and no faults on engine.

Will try with oil change. 5w40 ok or go with something thinner like 0w30 to get a more cleaning effect?

 

I would go with 5w30 or 10w30 first.

Gus
www.jagrepair.com

 

Tried oilchange this weekend, maybe a bit less sound. Hard to tell.
Will try with stetoscope to listen to engine.

 

Hard to say but if it goes away when the engine warms up I would tend to think it is an exhaust leak of some sort. When the eexhaust warms the parts swell and close the leak. I would look for a crack in the headers or cats or a gasket leak.

An internal engine problem (rod knock) typically won't go away when warm a oil starvation/drainback problem somewhere else will go away very quickly as pressure comes up.

You could drain the oil into a clean container and send some of it away for oil analysis. If it is a bad bearing you should see that in the oil.