The 6.0-liter Power Stroke engine has been troublesome from the day it was launched in the fall of 2002. It replaced a somewhat unrefined 7.3-liter diesel.
The powertrain was built by a longtime Ford diesel supplier, International Truck and Engine Corp., of Melrose Park, Ill.
For this version of the engine, International Truck designed a unique high-pressure fuel-injection system.
Most automakers use only electronic controls to operate the fuel injectors in a common-rail system. But the Power Stroke's fuel injectors are operated by a high-pressure oil pump as well as electronics.
According to several of the 150-plus complaints posted on the Web site of the National Highway Traffic Safety Administration, some trucks never even made it home from the dealership before the fuel injectors or turbocharger failed.
The engine also has been plagued with leaky fuel injectors, oil leaks, broken turbochargers, wiring harness troubles, faulty sensors, defective exhaust gas recirculation valves and bad computers.
Since the engine debuted three years ago, Ford has issued at least 77 technical service bulletins. That is far above average, even for a new engine. These bulletins tell mechanics how to diagnose and fix various problems.
By comparison, there have been eight service bulletins for GM's Duramax diesel V-8 and none for the diesel engine in the Dodge Ram truck. Both engines debuted at about the same time as the Power Stroke.
After just a year on the market, International almost completely redesigned the Power Stroke's fuel system, replacing or redesigning nearly 500 parts. That helped reduce the number of problems, but did not cure the engine of all its ills. Ford has voluntarily recalled the engine at least twice to fix various problems.
The troubles have caused a rift in relations between Ford and International.
The engine can be repaired and made reliable, says International spokesman Bob Carso. Engineers from Ford and International have fixed the problems that plagued the early versions of the engine, he said.
But Carso says the engine is extremely complex and requires "outstanding diagnostic capabilities" to properly identify and repair the faulty parts.