Customer 
The 2003–2007 Ford 6.0L Powerstroke might be the most well-known truck diesel around, and not always for the right reasons. The 6.0L is loved in some circles for its solid towing capacity, and hated in others for its infamous reliability quirks. In short, the 6.0L Powerstroke has achieved legendary status, and even worse, sometimes a cautionary tale.
Whether you are interested in buying one for work, play or restoration, buying a 6.0L Powerstroke requires awareness of its strengths and weaknesses, and what you have to check before your purchase.
In this guide, we will cover everything you want to know, including common trouble areas, maintenance considerations, performance potential, and whether this diesel is a diamond in the rough or a boat anchor.
The 6.0L Power Stroke diesel engine first manufactured by Ford during the early 2000s has always been a hot button topic among truck fans as the engine has endured its share of critiques in its early days for reliability issues, but with constant evolution and after market fixes, the engine developed into a capable and widely respected engine platform. Here you’ll see some of the major innovations surrounding it.
The 6.0L Power Stroke had a HEUI (Hydraulic Electronic Unit Injector) system, and although this injection system was advanced for its time, there were limitations. Recently tuning and improved fuel injectors have allowed for smoother fuel delivery, improved atomization, and more efficient combustion.
The 6.0L featured a variable geometry turbocharger (VGT) and provided better throttle response and towing power. With modern upgrades like more reliable VGT solenoids, upgraded vanes, and turbo performance replacements, older problems related to the early failures have been corrected and allowed for higher performance levels.
The factory Exhaust Gas Recirculation (EGR) system had huge weaknesses. Improvements have come in the shape of EGR coolers with welded designs on cooling elements, better bypass or delete systems, tuning to help avoid failure while still addressing emissions compliance.
Upgrading the factory head bolts to ARP head studs with stronger gaskets is the most popular fix for the 6.0L. This alone makes the engine more durable, allowing for more boost and more work.
The stock oil cooler would clog and cause overheating and EGR cooler failures, which required better solutions. After market, bulletproof oil coolers, or relocated oil coolers have been key innovations to better reliability and ensure engine health long-term.
ECU tuning has also improved the power, economy and reliability of the application. Combine ECU tuning with digital engine monitoring, you now have real-time data at your fingertips to monitor health and performance of the engine everything in a single device to minimize the risk of heavy failures.
The phrase “bulletproofing” has officially become synonymous with the 6.0L. The packages often include head studs, EGR coolers, oil coolers, and various reliability upgrades. This innovation of bundling has also made the 6.0L a great platform for work, and play.
Despite its innovations, including a variable geometry turbo and advanced fuel injection, it has also had its share of a bad reputation due to mechanical failures, and much of it was due to design deficiencies, emissions, and upkeep when it was supposed to be a work truck.
The EGR (Exhaust Gas Recirculation) cooler is arguably the most popular known problem. It clogs with soot, overheats, breaks and then leaks coolant, and ultimately head gasket failure.
The oil cooler is typically blocked by debris from the coolant system, which greatly reduces oil flow. Reduced oil flow means less lubrication, which takes more time on the EGR cooler and brings the strain on the engine overall.
From the factory, the TTY (torque-to-yield) head bolts will stretch under high-boost situations and allow for the head gaskets to blow. This is a problem when the vehicle is tuned for more power.
The 6.0L requires a high-pressure oil system to actuate injectors. Leaking seals all around the engine, STC (snap to connect) fittings, and standpipes are common leaks. These leak or leak air resulting in hard starts, stalling, or no start.
The variable geometry turbo (VGT) can get stuck with soot buildup. When this occurs, power will drop, turbo lag will increase, and the engine will struggle under load.
The HEUI (Hydraulic Electronic Unit Injectors) are highly sensitive to oil quality. The most common cause of injector issues is neglect, followed by dirty oil, resulting in misfires, rough running, and subsequently expensive injector replacement.
The FICM can only handle so many voltage drops or failures before hard starts, rough idle, and power loss occur. Heat and vibration are major contributors.
The factory plastic degas bottle cracks, hoses split, and the system can’t manage pressure spikes, leading to catastrophic failures and foiled head gasket plans!
Glow plugs, ICP (Injection Control Pressure) sensors, and wiring harnesses are common failure points that can also cause no-start or performance issues.
When buying a 6.0L Power Stroke, you should scrutinize the common weak points that characterize the engine’s reputation. First and foremost, you should find out if the truck has been “bulletproofed” (usually signifying upgrades such as ARP head studs replacing the stock head bolts that often fail and lead to blown head gasket).
The EGR cooler is another important element. The factory EGR coolers often rupture, causing coolant to leak out or inject white smoke. Look for signs of upgraded or deleted EGR cooler systems.
You should also check the oil cooler, as clogging often occurs and can lead to more significant damage; many owners replace them with after market versions.
You should pay special attention to the high-pressure oil system. The HPOP and STC fitting are important, as both will result in hard-start or no-start conditions if they fail; an upgraded STC fitting is a good indicator of preventative maintenance.
You should finally check the injectors; injectors often cause problems due to sticking or failing due to oil or fuel contamination. A documented service history with upgraded or replaced systems makes a 6.0L a much safer and more reliable option.
The 2003–2007 Ford 6.0L Powerstroke has its shortcomings, but with the right upgrades and maintenance it can still be a reliable and powerful truck. My suggestion when purchasing is to look specifically at whether the truck has been “bulletproofed” with service records. The 6.0L Powerstroke will travel anywhere from a cautionary tale to a reliably characterful workhorse.