I rebuilt a tractor ENGINE
when I was, like, 12.
The Big Bang Theory Season 1, Episode 2
It's the stupid ENGINE
that stopped working.
The Big Bang Theory Season 2, Episode 14
...of an internal-combustion ENGINE...
The Big Bang Theory Season 2, Episode 5
I got you a talking Thomas
the Tank Engine for Thanksgiving.
The Big Bang Theory Season 4, Episode 6
Does anybody know how to fix
combustion ENGINE?
The Big Bang Theory Season 4, Episode 19