What is this?

[rjg1987gn]

What is the round silver medallion (about the size of a dime) on the driver side engine block on a 1987 GN?

Can barely make out words stamped on the medallion "warranty voided if removed""

 

[Paul Lohr]

It sounds like a heat tab that machine shops or engine builders install. I think the center melts out of the heat tab at a certain temperature.

http://www.engineheattabs.com

 

[Hotrodbuick]

That's exactly what it is. If the engine gets over a certain temperature it melts or falls off and if your motor messes up because it got hot they will not warranty the work. Lot of salvage yards use them also.