History
Ford and Navistar: The 27-Year Partnership Behind the 7.3, 6.0 and 6.4 Power Stroke, and How It Ended
Published · 5 min read
For 27 model years, the diesel in a Ford pickup was not a Ford engine. From the 1983 F-250 to the 2010 Super Duty, it came from International, the truck and engine maker that became Navistar. The Power Stroke name was Ford's, but the 7.3, the 6.0 and the 6.4 were built by International and carried International's own names.
The partnership produced the most loved diesel of the era and the most argued-about one. It ended in a lawsuit.
1981-1994
A diesel Ford did not have to design
At the end of the 1970s, fuel economy rules began to apply to light trucks, and big gasoline V8s became a liability. In 1981 Ford signed an agreement with International Harvester to supply diesel engines for its light trucks. International already had an engine in development, the 6.9 IDI (indirect injection) V8, originally meant for its own medium-duty trucks. aggregated
Buying it in was faster and far cheaper than building a diesel from scratch. For 1983 the 6.9 went into the F-250 HD and F-350, rated at 170 hp and 315 lb-ft, with fuel economy closer to Ford's six-cylinder than to its V8s. aggregated
International itself was changing. It sold its farm equipment business in the mid-1980s and renamed what was left Navistar, so the same engines carry both names. For 1988 the 6.9 grew into the 7.3 IDI, and a turbocharged 7.3 IDI followed for 1993.
1994-2003
The 7.3 Power Stroke
During the 1994 model year, International replaced the IDI with an all-new direct-injection V8, the T444E. It shared only its bore, stroke and 7.3 liters with the old engine. Ford gave it a name to make the change obvious: Power Stroke. aggregated
The T444E used HEUI injectors, fired by high-pressure engine oil instead of a fuel pump, and nearly two million were built in Indianapolis before it left the Super Duty in early 2003. It is often called one of the best engines International ever built, and our 7.3 buying guide covers what to check on one today.
2003-2007
The 6.0, and the fight over who pays
The 7.3's replacement, International's VT365, went into the 2003 Super Duty as the 6.0 Power Stroke: smaller, with four valves per cylinder, a variable-geometry turbo, an EGR cooler and an engine oil cooler.
The 6.0 became the most complained-about diesel in our data. Owners filed 196 engine-related complaints with NHTSA per model year, against 61 for the 7.3 it replaced. Our myth check on the 6.0 traces most of them to one chain: the oil cooler, the EGR cooler and the head gaskets.
Fixing those trucks under warranty cost money, and the two companies disagreed about whose money it was. In early 2007 Ford said Navistar owed it a share of the 6.0's warranty costs under their agreement, and that Navistar had raised engine prices beyond the agreed levels. Ford reportedly began deducting what it said it was owed from the price it paid for engines. Navistar called the claims "totally without merit". Ford sued over the 6.0's quality and the unpaid warranty share, and Navistar sued Ford for breach of contract. verified
2008-2010
The 6.4, built during the lawsuit
The fight did not stop the next engine. The 2008 Super Duty got International's MaxxForce 7, sold as the 6.4 Power Stroke: high-pressure common rail injection, and in Ford's version two turbos in series instead of International's single turbo. The 6.4 did not fit the E-Series van, which kept the 6.0 through 2010. aggregated
In January 2009 the companies settled all their litigation. Ford would make a payment to Navistar, of an amount not disclosed, and Navistar would stop supplying Super Duty engines at the end of 2009. verified The 6.4 was the last International diesel in a Ford pickup.
2011-today
The 6.7: Ford's own
For 2011 Ford introduced the first Power Stroke it designed and built itself, the 6.7, developed with the Austrian engineering firm AVL. Its code name was "Scorpion", because the turbo and exhaust manifolds sit in the valley between the cylinder heads. It has a compacted graphite iron block, six head bolts per cylinder and Bosch common rail injection. aggregated
The 6.7 has its own weak spot, the Bosch CP4 high-pressure fuel pump, recalled twice on 2020-2022 trucks and covered in our 6.7 problems by year. By our count it has drawn the fewest engine complaints per model year of the four.
Four Power Strokes, two builders
| Engine | Super Duty years | Built by | Supplier name | Injection | Turbo | Engine complaints per model year |
|---|---|---|---|---|---|---|
| 7.3 Power Stroke | 1994.5-2003 | International (Navistar), Indianapolis | T444E | HEUI unit injectors | Single | 61 |
| 6.0 Power Stroke | 2003-2007 | International (Navistar) | VT365 | HEUI unit injectors (second generation) | Single, variable geometry | 196 |
| 6.4 Power Stroke | 2008-2010 | International (Navistar) | MaxxForce 7 | High-pressure common rail | Two in series (compound) | 53 |
| 6.7 Power Stroke | 2011-2026 | Ford | “Scorpion” (Ford code name) | High-pressure common rail (Bosch) | Single, variable geometry | 42 |
Engine facts: Wikipedia, Ford Power Stroke engine and Navistar VT engine (accessed 2026-10-31). Complaints: engine-related NHTSA owner complaints, the sets of our engine comparison, divided by model years sold; a count of reports, not a failure rate (older trucks have had longer to collect them, and fewer owners filed online in the 1990s).
Read the last column with care. A 1999 truck has had 27 years to collect complaints and a 2023 truck three; on the other hand, far fewer owners filed online in the 1990s. The 6.0 stands out either way.
What it means if you own one
- You will see both names. International called these engines T444E, VT365 and MaxxForce 7, so manuals, forums and parts listings may use either name for the same engine.
- The 6.0's reputation comes with a fix list. The problems Ford and Navistar argued over are the ones owners fix today. Our 6.0 bulletproofing guide explains what that word really covers.
- A 2011 or newer Power Stroke is a different engine family, with nothing in common with the Navistar engines but the name.
FAQ
Who made the 7.3 Power Stroke?
International (Navistar) built it in Indianapolis as the T444E and supplied it to Ford, which sold it as the 7.3 Power Stroke from the 1994 model year to early 2003.
Is the 6.7 Power Stroke made by Navistar?
No. The 6.7, introduced for 2011, is the first Power Stroke designed and built by Ford, developed with the engineering firm AVL.
Why did Ford stop using Navistar engines?
The companies fell out over the 6.0. In 2007 Ford said Navistar owed it a share of the engine's warranty costs and had raised prices; Navistar denied it and sued for breach of contract. They settled in January 2009, and Navistar's supply of Super Duty engines ended at the close of 2009.
Go deeper
- Is the 6.0 really that bad? · Buying a used 6.0 · Buying a used 6.4
- Every engine and its years on one page · How the Cummins got into the Dodge
- Platform pages: 7.3 · 6.0 · 6.4 · 6.7
Sources. Wikipedia: Ford Power Stroke engine, International Harvester IDI, Navistar International and Navistar VT engine (CC BY-SA, accessed 2026-10-31; facts restated, not copied). Wards Auto, "Ford wants Navistar diesels", 1 February 2007. The Truth About Cars, "Navistar and Ford settle their differences", 15 January 2009. RV.com, "Ford, Navistar settle lawsuits". Complaint counts: NHTSA owner complaints (US government public domain), the sets of our engine comparison. Torque Index takes no paid placement.