Thank you for the suggestion, but since the grill is vertical I might have a problem holding it in place while the epoxy dries. What I did was to use some Super Hot Stuff on the bumper side and sprayed the grill with a quick activator. That way I could hold it with my hand for 30 seconds and it will never come off...unless you break it apart. BTW, it was the grill with the temperature sensor between the fins.
Howto for grill 1997 C-280
I need a bit of help on how to secure the driver side grill piece, the inboard side attachment is broken. This is the small ~8" widex3" high plastic grill next to the opening at the bottom of the bumper. I'd like to secure it before it falls off especially when a new one probably costs $1,000. 
