Ford Trucks with 5.4-liter V8 Engines
From 2003 to 2010, Ford produced many trucks with a modular 5.4-liter V8 engine that featured an innovative three-valve cylinder head. Despite being relatively powerful, those engines were known to develop serious issues, especially when they crossed the 100,000-mile mark. The main problem is the camshaft phaser, a device that changes the angle of the camshaft to open the valves. When this system fails, the idle becomes rough and the engine loses power. The first sign of trouble is strange engine noises.
The repairs are costly since they require a new phaser, and possible a new set of camshafts and valves, among other things. Besides the F-Series, Ford put this engine in the Expedition, the Explorer and the Lincoln Navigator. So, if you are looking to buy a used Ford truck, avoid engines with the 5.4-liter V8 and three valve heads, especially if they have covered a lot of miles.