Dear Gilly,

I removed the valve cover again. Surpizingly I found out that the chain was tight. I believe as tight as It should be. There is still a play about 1/16". I have no idea what the spec is. But there was a big difference caompare to when I had the old tensioner. Before I could see about half inch play and I was able to easily slide the chain guide out without removing the tensioner. As I described there is still a similar rattling noise but now it comes only when the car is stopped and it is in R or D and rpm drops to around 500. As soon as the car moves it goes away.
I realized that there was a play in the new rail guide in vertical direction in one of the holes that is actually not round and kind of oval shape. The oval shape is in the direction that the chain moves and I didn't expext any play in another direction. I can feel the play and to me that could be the cause of this remaining noise. Is there any possibility that that shaft is worn out since the guide is some sort of rubber and the shaft is steel?

I think for now I will drive it the way it is and see if it gets worse over time. If I can change those shafts and if it makes sense to you, I'll appreciate if you advice me how and where I can buy them.

Let me know what you think.

Best regards,
Sean