Skip to content

Ford 6.4L PowerStroke Engine (Specs, Reliability & Issues)

  • by
  • 6 min read

Last Updated on: 16th November 2023, 02:39 am

Ford introduced the 6.4L Power Stroke engine in 2008. It was cleaner, quieter, and more powerful than its predecessors and any other International Navistar engine built for Ford cars before to it.

This new 6.4-liter diesel V8 engine was the first to come standard with two turbochargers and a diesel particulate filter (DPF), both of which were necessary to meet the government’s tighter emissions regulations.

When compared to the 6.0L PowerStroke, NOx and particulate matter emissions were reduced by 50% and 90%, respectively.

In this article, we’ll be discussing the design, reliability and issues of the Ford 6.4L PowerStroke engine.

Design of the 6.4L Power Stroke Engine

Like the 6.0L Power Stroke, the 6.4L Power Stroke has a cast-iron cylinder block and bed plate, which removes the need for traditional main bearing covers.

The engine block is secured to the bed plate with four bolts per major.

Powdered-metal connecting rods of the 6.4L are far beefier and stronger than the 6.0L’s, capable of handling more than 900 whp. On top are cast iron cylinder heads with four valves per cylinder.

Ford 6.4L PowerStroke Engine
  • The 6.7L’s cylinder heads have four head bolts per cylinder, similar to the 6.0L’s, although the 6.7L’s head bolts are 16 mm instead of 14 mm.
  • The 6.7 Power Stroke has an OHV pushrod valvetrain and a single cam in the block.
  • The valves are controlled by the rocker arms.
  • Two valves are opened and closed simultaneously by each rocker arm.

HEUI was replaced with direct high-pressure common rail fuel injection in the 6.4L Power Stroke engine.

The Siemens VDO K16 high-pressure fuel pump, which is located in the lift valley’s rear, provides the gasoline. The pressure rating of the K16 gasoline pump is 24,650 psi.

The engine also included piezoelectric injectors, which were a first in the industry.

These injectors may execute five operations throughout each cylinder’s power stroke, allowing for significantly more precise fueling than HEUI injectors.

A compound turbo system, which is a compact bundle of BorgWarner turbochargers, is installed in the engine.

It consisted of a low-pressure turbocharger with a fixed geometry of 65 mm and a high-pressure turbocharger with a variable geometry of 52 mm.

Reduced turbo lag and improved overall performance are among the benefits of this twin sequential turbocharger technology.

All 6.4L diesel engines come with an air-to-air intercooler as standard.

It features:

  • more exhaust gas recirculation (EGR)
  • two EGR coolers
  • a stronger motor for the EGR valve

Exhaust gases now make up about a 25% of the intake air, reducing NOx emissions. To restrict particulate emission, a diesel particulate filter was placed in the engine exhaust system (DPF).

The manufacturer provided a unique regeneration technology to make the DPF self-cleaning.

More fuel is fed into the engine during the exhaust stroke during active regeneration to effectively burn off the trapped particles in the DPF.

International Navistar’s final diesel engine for Ford was the 6.4L Power Stroke. In 2011, Ford released the 6.7L Power Stroke, a 6.7-liter V8 diesel engine designed and manufactured in-house by Ford.


  • Manufacturer: International Truck and Engine Corp.
  • Production years: 2008-2010
  • Cylinder block material: Cast iron
  • Cylinder head material: Cast iron
  • Fuel type: Diesel
  • Fuel system: Common rail direct injection
  • Configuration: V
  • Number of cylinders: 8
  • Valves per cylinder: 4
  • Valvetrain layout: OHV
  • Bore: 98.2 mm (3.87 in)
  • Stroke: 105.0 mm (4.13 in)
  • Displacement: 6,400 cc (389 cu in)
  • Type: Four-stroke, turbocharged
  • Compression Ratio: 17.5:1
  • Power: 350 hp (261 kW) at 3,000 rpm
  • Torque: 650 lb-ft (881 Nm) at 2,000 rpm
  • Engine weight: 1130 lbs (512 kg)
  • Firing order: 1-2-7-3-4-5-6-8
  • Engine oil weight: SAE 10W-30 Super Duty Diesel Motor Oil or equivalent, SAE 15W-40 Super Duty Diesel Motor Oil
  • Engine oil capacity: 14.2 litres (15 qts) – with oil filter
  • Oil change interval: 10,000 miles (15,000 km) or 6 months
  • Applications: Ford F-250, Ford F-350, Ford F-450, Ford F-550

Problems & Reliability

The 6.4L retains some of the 6.0L’s negative and positive design aspects while sharing the same core architecture.

However, the 6.4 Power Stroke is expected to exceed the 6.0L variant in terms of reliability.

Factory pistons are prone to craking at first. The high stock boost pressure of 40-42 psi is most likely to blame.

On the other hand, the 6.4L engine boasts stronger connecting rods that can resist the harshest abuse.

Second, blown head gaskets continue to be a problem as a result of stretched head bolts under high cylinder pressure.

The 6.4L, like the 6.0L, has four head bolts, but the bolt size has been raised from 14 mm to 16 mm, and the problem seems to be less widespread.

The absence of oil lubrication for the rocker arms is the third source of concern. This results in rapid wear of the rocker arms’ pressed-in balls, as well as increased friction and heat in the valvetrain.

Apart from that, the 6.4L has the same oil cooler design, which is prone to clogging.

An oil cooler that isn’t working properly might cut off coolant supply to the EGR cooler, causing it to burst.

The disadvantage of the 6.4L Power Stroke engine’s DPF regeneration procedure is that a little quantity of gasoline may mix with the engine oil.

It’s uncommon for owners to report emptying an additional gallon of oil after an oil change.

Regeneration also has a negative influence on fuel use. Due to its ultra-tight tolerances, piezoelectric injectors are more sensitive to fuel quality than prior HEUI injectors.

If the 6.4L injectors fail, the pistons may be ruined.

The 6.4L Power Stroke was designed to look a lot like its troublesome predecessor, the 6.0L.

Engineers at Ford, on the other hand, were focused on resolving or at the very least minimising the past problems. As a consequence, the 6.4 engine is usually reliable and delivers exact results.

  • Andy Lewin

    Andy Lewin is a senior mechanic, ASE qualified master technician, and an experienced automotive engineer. He's passionate about serving the automotive community with the highest-quality and trustworthy information on all things automotive. He loves to write about car repairs, maintenance, car modifications and tuning, faults, and much more.

Share this article
Available for Amazon Prime