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Ford 6.7L Power Stroke Engine Review

6.7L Power Stroke Engine

The 6.7L Power Stroke is a 6.7-liter V8 turbocharged diesel engine. Starting with a clean sheet, in 2008 Ford Motor Company began to develop a new diesel engine for the Ford Super Duty in-house. During its developmental stage, this new product has codenamed the Scorpion, and when Ford officially introduced it in 2011, the engine was already designated as the 6.7 Power Stroke. Ford's 6.7L Power Stroke replaced the 6.4L Power Stroke and became the first Power Stroke engine not manufactured by International Navistar (nearly 30 years of partnership).

While the majority of current diesel engines use heavy cast iron, the 6.7L Power Stroke has a cylinder block made from compacted graphite iron (CGI). Its deep-skirt block also has nodular iron six-bolt main caps highly common on the 7.3L Power Stroke instead of the 6.4L's bed plate. This block layout in addition to the CGI material provides significant weight savings over the 6.4L predecessor. The 6.7 Power stroke also features a steel crankshaft, powdered-metal cracked-cap connecting rods made by Mahle, and Federal Mogul cast-aluminum pistons. The connecting rods have an end cap that is rotated 45 degrees to increase strength. The engine was equipped with piston cooling jets for lower piston and combustion temperatures. This affects positively on engine longevity. All 6.7L blocks are manufactured by American foundry company, Tupy.

First for the truck segment, Ford's 6.7L Power Stroke uses cast-aluminum cylinder heads. They feature the reverse-flow design. Each cylinder has for valves (two intake and two exhaust valves; 32 valves total). Every valve is equipped with its own rocker arm and pushrod. The intake air goes through ports inside the valve covers, while the exhaust gases into exhaust manifolds located in the lifter valley (in a traditional V8 engine, the exhaust exits from the outside). In engine valley, there is also a Garrett GT32 DualBoost variable geometry single sequential turbocharger (SST). The exhaust volume of this system is smaller, providing a much more dynamically responsiveness of the engine. The compressed and hot intake air is cooled by a water-to-air intercooler which is connected to a secondary cooling system of the engine. This powertrain secondary cooling system is also used for cooling of EGR circuit, transmission fluid, and fuel cooler. The primary and powertrain cooling systems have their own water pump, thermostats, degas bottle, and radiator.

The 6.7L Power Stroke is equipped with a high-pressure common rail direct injection. The Bosch CP4.2 fuel pump supplies fuel under a 30,000 psi for the 19 mm Piezo actuated Bosch injectors with 8 hole nozzles. The fuel injectors are capable of pulling off five events per combustion cycle.

In 2015, the GT32 SST turbocharger was replaced by the Garrett GT37 with single VGT. The GT37 features a larger 88 mm compressor wheel as well as increased turbine wheel to 72.5 mm up from 64 mm in the GT32. The fuel system also was upgraded with a higher-flowing Bosh CP4.2 high-pressure fuel pump with a larger stroke and optimized injector nozzles. With made improvements, the engine is able to produce even more power.

Engine Specs

Manufacturer
Ford Motor Company, Chihuahua, Mexico plant.
Production years
2011-present
Cylinder block material
Compacted graphite iron
Cylinder head material
Aluminum
Fuel type
Diesel
Fuel system
Common rail direct injection
Configuration
V
Number of cylinders
8
Valves per cylinder
4
Valvetrain layout
OHV
Bore, mm
99.1 mm (3.9 in)
Stroke, mm
108.0 mm (4.25 in)
Displacement, cc
6,700 cc (406 cu in)
Type of internal combustion engine
Four-stroke, turbocharged
Compression Ratio
16.2:1
Power, hp
270-450 hp (201-335 kW)/2,400-2,800
Torque, lb ft
675-935 lb-ft (915-1268 Nm)/1,600-1,800
Engine weight
970 lbs (440 kg)
Firing order
1-3-7-2-6-5-4-8
Engine oil weight
CJ-4 or CJ-4/sm;
SAE 10W-30 - normal use;
SAE 5W-40 or 15W-40 - for severe duty or biodiesel applications.
Engine oil capacity, liter
12.3 l (13 qts) - with oil filter
Oil change interval, mile
7,500 (12,000 km)/12 months
Applications
Ford F-250, Ford F-350, Ford F-450, Ford F-550, Ford F-650, Ford F-750

6.7 Power Stroke Engine Problems and Reliability

Ford's 6.7L Power Stroke diesels are solid engines, extremely durable, and reliable, with only a few problems/issues. One of the big improvements in term of reliability is that the 6.7L Power stroke no longer would rely on four bolts per cylinder holding down the cylinder heads. There are six bolts per cylinder now. That will reduce the risk of head bolt stretch and head gasket failure - blown head gasket and coolant/oil inside cylinder.

Turbocharger failure is the biggest what can happen to the 6.7 Power Stroke. The first years of production, engines have a fairly complicated turbocharger with ceramic bearings (the tiny GT32 SST), which were prone to premature failure. Latest engines are fitted with another turbocharger unit, which has more reliable steel ball bearings on the turbo shaft. Turbo failures are reported so far mostly on 2011 and 2012 models.

Engines produced in 2011 had weak glow plugs, which can potentially break off and lead to massive engine damage inside the cylinders. It is safe to replace them with the updated ones. There are also problems related to some soot clogging on the EGR cooler and EGR valve, issues with EGR temperature sensor, and plugged DPF filters as well. Coolant leakages are possible around the turbocharger area and from the primary radiator of the cooling system.

Overall the 6.7 Power Stroke engine has proven to be a very robust engine. It is highly important to do regular oil changes and using high-quality motor oil that meets Ford's lubricity requirements for this diesel engine. With proper maintenance, the engine will last hundreds of thousand miles.

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