[Dave at Pelican Parts]

If the T-stat fails, the spring forces the flaps into the "open" position--as in, "cool the engine as much as possible". Take a look at how the flaps move, including the fiddly linkage bits on the right side. And also look at how the right-side flap works with the oil cooler, where the front edge of the flap winds up when the flaps are "open".

--DD