It's amazing how resilient an internal combustion engine can be, at least some of them. In this video, the Russian guys from the Garage 54 channel show the abuse a powerplant can take by getting a Toyota diesel running after being buried underground for around a year.
As part of one of the channel's stunts, Garage 54 buried a Toyota 2CT diesel engine in a hole. They left the wiring, air intake, and radiator exposed in order to see if it was still able to run later. The guys then forgot about it until commenters reminded them.
The bad news is that the engine doesn't immediately startup. There's an issue with the ground wire that prevents it from turning over. The next step is to dig up the powerplant and figure out the problem.
The engine is absolutely caked in dirt. Hosing it off is enough to expose all of the vital parts.
A year underground has not been kind to the Toyota diesel engine. The cylinders are full of water, and the turbo is seized. After some basic maintenance, the guys are able to start testing whether the mill still runs.
Even with several healthy sprays of ether, the engine refuses to turn over. After several attempts, the Toyota diesel finally roars to life.
This is a fairly impressive result. The engine needs a turbo, and the starter is on its last legs. A lot of the wiring and tubing also need to be replaced. Still, only minor work was necessary to get the mill running after a year below ground, including getting through a Russian winter.