Gasoline has A LOT more chemical-potential energy per serving than diesel fuel or kerosene. This is why a diesel engine requires a much bigger displacement to produce the same power of a smaller gasoline engine.

If fueled by gasoline, a diesel engine will experience much higher peak combustion chamber pressures and temperatures. Gasoline needs more heat to start ignition, but it burns hot and fast once ignited. This can damage the pistons, rings, conrods, bearings, and especially the head gasket. Note the stories of a loud rapping noise and rough operation on diesels that have accidentally been fuel completely by gasoline.

However, fortunately a diesel engine will usually become unsustainable if the fuel tank is contaminated with enough gasoline--the car would become undriveable before any real damage could occur. Also, diesel engines are structurally sound, and have a higher tolerance for BS than a gasoline engine.

If the engine were forced to remain in operation, the head gasket would probably eventually go first, followed closely by the rings. If any pre-existing metallurgical problem existed in the pistons, conrods, etc... they would likely fail too.

Some manufacturers recommend mixing gasoline with diesel fuel during excessively cold conditions, if kerosene is not available.

I've experimented with a gasoline/diesel mix in my car (don't ask why), and noted a nice jump in power with less WOT smoke--no doubt the higher temp helped to oxidize more fuel... However, the noise and vibration definitely increased.

-Joe