I am taking it as the counter balancer plug was removed then diesel poured on the crank. Hoodlum is assuming there was no oil in the balancer based on the nothing came out, but maybe oil came out. Just nothing came out when diesel poured on the crank? That would be good since it would mean bad seals. I am also taking it that the metal is in the crank case. If that metal is steel, 100%, the engine needs to be torn down. If that metal is aluminum dust from a piston, a rinse may be enough. I would repeat the rinse until you do not get a silver hue then one more time to be sure. At least the last rinse should be mixed 2 stroke gas. You can put a rubber strap like an X trough the connecting rod and around the cylinder studs to hold it fairly centered while pulling over. That will agitate the rinse and get more out. If you pull it fast enough, most of the fluid will get splashed out.