MBWorld.org Forums - Timing Chain? Timing Chain Tensioner? Or What?

So I bought my 2003 E320 about 3 months ago with 119k miles. Ever since there has been a tapping/rattling sound which I have not been able to find/fix. The car has almost 123k miles now. I have cleaned the MAF sensor, replaced spark plugs, changed the oil and filter and the air filters, and have used fuel additives in some full tanks, 1 Chevron and and 2 Lucas. I like Lucas better, the engine seems to run smoother and quieter. I also replaced the crankshaft position sensor last week as it would not start sometimes and the scanner showed the code for it. I believe the motor mounts need to be replaced as they show some leakage, but there is no vibration at idle at all, just noise on acceleration.

Now the tapping noise does not happen at idle, even if I rev it. It only happens on acceleration and goes away as speed increases. But if I get my foot off the pedal for a second or two when accelerating, the tapping goes away, and comes back when I press the pedal again. So basically it makes the sound only when there is load on the engine.

After reading extensively on google, I am thinking it might be the timing chain or the tensioner. I have posted a couple of videos on youtube. One for cold start and one for warm start. Here are the links:

Cold Start:

Warm Start:

Any advice and comments are greatly appreciated.

Thanks, J
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