If you regularly tow a large trailer or fifth-wheel RV, it’s difficult to ignore the allure of the Ford 6.7 Power Stroke V8. It is the most powerful of America’s big three diesel engines, a list that also includes the 6.7 Cummins turbo diesel and GM’s 6.6 Duramax diesel. At the time of writing, the powerplant produces up to 500 horsepower along with an abundant 1,200 lb-ft of torque, which means that you can tow up to 40,000 pounds with a fifth-wheel. Maximum payload is also impressive at 6,935 pounds.
That capability comes as a result of improvements and revisions made to the 6.7 since the original version debuted back in 2011 as the beating heart of Ford’s full-size and heavy-duty trucks. This was the first Power Stroke engine to be entirely built by Ford, although it was still designed in collaboration with Austrian engineering firm AVL. Standout features include reverse-flow aluminum cylinder heads with dual water jackets, a compacted graphite iron (CGI) block, a high-pressure common rail Bosch fuel system producing up to 29,000 psi of rail pressure, a dual-compressor-wheel VGT turbo, and a liquid-to-air intercooler.
It’s indeed a statement piece — although it has also occasionally made some wrong statements. While the 6.7 Power Stroke is generally dependable, a number of owners have reported reliability issues, especially with the early versions of the engine. This shouldn’t come as much of a surprise, given it was Ford’s first attempt at producing the oil burner in-house since the early ’80s.
2011 is often billed as the most problematic year for the 6.7 Power Stroke V8
Although many have had positive experiences and thus dubbed it a great engine overall, a couple of faults have developed over the years that make 2011 one of the less desirable years for the 6.7 Power Stroke diesel. Some owners have complained the most about damaged glow plugs in the cylinder head. The exhaust valves in some 6.7 engines built prior to March 2011 are said to be defective and prone to cracking due to heat.
When faulty valves fail, it can cause a catastrophic engine failure. Some owners say failure may happen suddenly without warning. Reporting their experience on a PowerStroke.org forum, user libertynd said, “Truck downshifted and seemed to lose power while pulling a trailer with a skidsteer. No CEL or any indicator lights. Within a few seconds developed an engine knock and then total failure … Only indicator was a low oil pressure warning after the engine had seized.”
Another common issue with the 6.7 Power Stroke diesel in 2011 Ford models is injection pump failure. The Bosch CP4.2 is known to often fail because of metal-on-metal contact within the pump, which can wreck the fuel system. This can be very expensive to fix. Also posting on the PowerStroke.org forum, owner bbrambila, said they were quoted $10,500 to replace the complete fuel system. They said, “One of my trucks is a 2011 F350 6.7L with 220,000 miles and it just had a CP4 failure and we are now facing a $10,500 repair from the Dealer.”
2012 to 2014 versions of the 6.7 Power Stroke had many of the same issues as the 2011 model
Although the 2012 through 2014 Ford 6.7 Power Stroke model years appear to have fewer problems compared to the 2011 model, other issues persisted throughout the first generation.
Faults include problems with emissions systems like exhaust gas recirculation (EGR), which recirculates a portion of discharged exhaust gases back into the engine’s intake to lower combustion temperature and reduce nitrogen oxide (NOx). The EGR cooler plays a crucial part in this process, as it lowers the temperature of the exhaust gases that are routed by the EGR system. However, carbon deposits can collect on the EGR cooler core and eventually clog and restrict the performance of the EGR system. This can cause the engine to overheat or reduce performance to the point an EGR cooler replacement is necessary.
Turbocharger failure is also a common concern with the first gen 6.7. The variable geometry turbine is said to be much smaller than the engine’s power output and boost requirements. As a result, it was prone to overspeeding, which leads to excessive stress and heat that often damages the ceramic ball bearing. Coolant leaks and NOx sensor problems were also a real nightmare for some owners.
The good news is that Ford has since corrected most of the reliability and quality issues encountered by owners. As such, reliability shouldn’t be a cause for more recent Ford models equipped with a Power Stroke engine – aside from a surprisingly stubborn CP4 issue, that is.