grashley said:
I know of no issues with the 6.7 diesel. I have one.
There are plenty...
Cracked valves, turbo issues, radiator issues, bad sensors causing full engine shutdowns, glow plugs detaching causing complete engine destruction. Here's some light reading: http://www.thedieselstop.com/forums/f149/
As someone that owned Ford trucks for years, I can tell you that the 7.3 liter offered from 1999-2003 was by far the most reliable.
The 6.0 offered from 2003.5-2009 was an absolute failure which resulted in a lawsuit between Ford and International leading to Ford building their own engines.
The 6.4 was notorious for poor fuel mileage and mainly for it's incredibly poor radiator design which has led to countless failures.
The 6.7 has been ok and seems to be getting better. Now that they have seemingly fixed the cracking exhaust valve problem, the weak link is the fuel system. They tend to be very finicky and Ford has been notorious for finding ways out of the warranty leaving customers with a $10,000-12,000 bill for its replacement.
The past 13 years of issues have caused a lot of us to look at other manufacturers. When it came time to replace my 2002 Ford F-350, I had no choice but to look at the Ram and it's venerable Cummins engine.