I have a 1994 F250 Diesel. It has the International 7.3 Liter. The beast has under 150k miles on it and has not given me any problems. It definitely has that "ticking" sound. I too have thought it was a sticky hydraulic lifter or something.

Today I approached a local [Philly] Diesel mechanic. He's torn down a number of these motors and even showed me one that was torn down. He was certain the problem was a deformed cam. He said just keep the oil up and maybe add something extra viscous and it's the best thing you can do. He showed me another 1997 F250 Diesel with only 160K miles and some kind of major broken valve. He said they kept their oil changed so I'm guessing it's just a crapshoot short of replacing the cam.

Has anyone else had a different experience?

Thanks! JH