As darkness fell on the Walmart parking lot in Goodland, Kansas, my coworker Freddy and I couldn’t stop scratching our heads. “What’s wrong with this little Jeep?” we asked ourselves. Eventually, we packed up and drove to our motel, where I struggled to get a single moment of sleep. My mind was—and remains—focused squarely on that little Go-Devil engine.

There are few vehicles on this earth simpler than an old Willys Jeep. The engine, made up of three and a half pieces of rusty iron, is about as complex as an anvil, so you’d think diagnosing a problem should be child’s play. And yet, the fault here still escapes me.

In case you didn’t read , here’s a refresher on what happened: I was driving down the highway at about 40 mph (with good oil pressure and coolant temperature), when I heard a loud boom; the engine cut off. Subsequent efforts to crank the engine yielded a sound that indicated low compression in all cylinders (this was confirmed with a compression tester).

Yesterday, Freddy and I pulled the timing gear cover and oil pan: everything looked perfect. The gears were fine, the cam was fine, the crankshaft looked like a crankshaft. Plus, there was nothing in the oil pan except a few chunks of RTV sealant. Nothing to see there, really.

So we pulled the head and cranked the motor by hand, upon which we confirmed that valve timing is on point:

All this motor needs to make compression is valves that seat, rings that seal, and a lid to keep the gases in. Since all four sets of piston rings failing simultaneously is basically impossible, and the valves appear to be seating properly, that leaves the cylinder head as the culprit. Does it seem odd that the head would cause the engine to die suddenly at highway speeds without warning? Yes, yes it does.

Freddy and I will check the head for warpage with a straight edge, and then we’re headed to Denver to pick up and install a new gasket. Any Denver-area readers are welcome to join us.

If a new gasket doesn’t make any difference, and the head doesn’t seem warped, then there’s clearly some dark magic going on with this little Go-Devil. Luckily, Moab is filled with wrenching magicians to fight back the evil compression-killing spirits.