Kinda worried. I started up my xkr with 6k miles this afternoon. It started sounding like it's a small knock, but went away once it was warmed up. So made me believe it could be tensioners but I had them changed to third(I believe) generation by my jag mechanic last summer. But the car hasn't been started in 6 weeks could it just be the engine was not lubricated? What should I do, I'm really worried.

Thanks for your inputs.
Mike

 

If the knock is consistent, remove the supercharger belt and try again. It might be the coupler.

 

Another knock source can be main belt tensioner. Shine a light on it while someone else starts the car. If it jumps in time with the knock, usually it means a problem with one of the idler pulley bearings...an inexpensive repair.