The telltale signs were black soot coming from failed gasket areas.…as well as having my wife watch for smoke when starting to confirm.
I concur 110% .. I will add it might take some time for it to accumulate enough carbon to be noticeable if it's a recent issue
I also advise everyone the following six ancient wisdoms when having wife or gf help you as "soldier B" ,,,
1: per Murphy, tasks take longer than they should
2: wives and gf's might get angry, or never help you again, if a task takes longer than you said it would
3: as we age, most tasks take longer than we say it will
4: as we age, all tasks take longer than they did 20, 30, 40, 50, 60 years ago
5: as we age, we get more wrapped up in a task, and forget the unfinished task we were in the middle of beforehand
6: wives and gf's can be a major distraction all on their own, and deny having done anything to distract you when the SHTF
Hence, make sure you and female soldier B have nothing previously running in the shop or garage or barn or on the stove..
Else there will be "telltale signs of black soot" and smoke emitting from something(s) other than your current task
If you ask me how I know,, I plead the 5th, your honor..