It wasn't Death Rattle (whew!)
 

More than one thing can rattle under the hood - er, sorry; 'bonnet.' After a recent lengthy LAX run had what I feared was 'Death Rattle' (timing chain, tensioner, and/or guide rail issues) pop up as a rattle that was present at idle and low speed but went away at higher rpms on the highway. Not good. Drove the car home praying the whole way I wouldn't grenade the engine with a timing chain catastrophe.

Naturally I assumed worst case and it was time to replace all the above before it did blow up. I replaced first the timing chain tensioner - no change. But then I started listening and looking further, and found it was something else entirely. Instead of a $400+ parts haul I got lucky with $18 for the Uro replacement of the serpentine belt tensioner damper, which had I read the FAQs would have known it was a frequent failure part (the rubber grommets rot out and disintegrate, see pic below) on these cars and sooner suspected it. To the untrained ear and eye (mine) it simply had to be the worst thing possible. But it wasn't. Whew!
https://cimg6.ibsrv.net/gimg/www.nor...e93fa6fbf0.jpg
Note the conspicuously missing rubber bushing.

For convenience, as a reminder here is what real death rattle sounds like and what first to do about it:

Thank you for the post sir.

i think my dampener bushing is on the way out. Looks like it’s coming apart...

Assuming the engine mount needs to come out to get to it?

Not necessarily. I was able actually to reach in through the back of the motor, under the upper mount with a 13mm combination wrench (open end) and grab it (my arms and fingers are somewhat long and slender). Another way would be to pull the passenger front wheel, and peel back or remove the fender liner to go straight in that way; to me that would have been easier than pulling and re-installing the upper motor mount.

^^ what he said.
I just did my water pump, pulley, friction wheel, and serpentine belt. If you pull the passenger side tire and wheel liner, it’s right there in front of you. I did have to drop that side of the engine to get to the bolts for the friction wheel, but you can do the tensioner without going that far. You can reach it fine.

Thank you, sirs. Good to know. 🙏