C220 "growling/diesel" sound at ~1000-1200rpm

[js81]

Hey all:

Got another potential issue with my 96 C220... in addition to my blown head gasket (working on a temporary fix this weekend until I can replace it or sell the car), I have just noticed a deep growling sound between 1000-1200rpm (thereabouts - I'm under the hood moving the throttle, not looking at the tach). It occasionally (randomly) makes the sound at idle - AC on or off doesn't matter - but it consistently does it every time you give it throttle. Just does it right off idle; once above that, it goes away. Is my timing chain about to go, too? Any other thoughts? I love the car, but its quickly proving that "there's no such thing as a cheap Mercedes." :-(

[hvmercy]

take a video and post it here so we can all determine collectively what it is.

[wichipong]

i believe belt tensioner needs adjusting... mine is that way...

[js81]

Thanks, hvmercy and wichipong. I'll try to video it this afternoon and post it here (have a funeral to go first, unfortunately).

EDIT: Didn't get to video, unfortunately - been pouring the rain here all day today. I'll post it as soon as I get a break in the weather... thanks, guys. :-)

EDIT 2: Thanks for the offer of help, but my head gasket problem is back with a vengeance. Therefore the growl-y noise under the hood is of no concern to me at this point... :-( Another problem for another day.