How Navistar Almost Killed Ford’s Powerstroke Lineup

In the automotive world, partnerships are very common. Seeing manufacturers use other company’s technologies, platforms, or engines is nothing new, and a good example of this would be Dodge and Cummins. And Cummins has been supplying the motors for Dodge’s heavy-duty trucks since the 1980s/1990s, and there’s a whole bunch of other examples just like that.

If we rewind the clock a little bit, we can go all the way back to the 1980s when Ford wanted to release their own diesel-powered trucks. Now, this is something that GM and Dodge had already done. They had already come to market, and they were doing very well with their diesel-powered trucks, so it was Ford’s turn to join those two and try and take some market share.

How It Started

International Harvester started development work for their own V8 diesel engine in 1978, and it was based on their existing 446 cubic inch gas engine. It’s a little weird that they were developing a diesel engine off of a gas engine, but for them, it made sense because of decreased tooling cost. They didn’t have to create a whole new, you know, assembly line and a whole bunch of new tools just to put this engine together.

Now, International started that development in 1978, and Ford really wanted to put diesel engines in their trucks in the 1990s. It’s not exactly clear why Ford decided to work with International. Still, nonetheless, they signed a 500 million dollar deal, and that was that International was now the new supplier for the diesel engine in Ford trucks.

That relationship continued all the way up until about 2011 to 2014, when it completely fell apart. While things were great at the start of their partnership, basically everything fell apart at the end, with faulty motors, consumers being screwed over, Ford having to deal with billions of dollars in repairs, and more. So, the question is, what happened between the start of the relationship and the end? How did things go so wrong?

The 6.9L IDI

To understand what went wrong with this partnership, we need to take a step back and look at where this all started, with the 6.9 IDI engines supplied by International for Ford to use in their pickup trucks. Most of you probably haven’t heard of this engine, and that’s because diesel engines weren’t as popular back then as they are now. Finding a working truck with the 6.9 IDI isn’t exactly an easy task.

Ford’s new diesel debuted in late 1982 and went on sale as 1983 models, with the all-new diesel engine being offered as a $2000 optional upgrade. The first advertised power rating for these new diesel trucks was just 161 horsepower and 307 pound-feet of torque. Compared to today’s standards, that’s what you would probably call gutless. Rather quickly, though, that advertised power was increased to 170 horsepower, thanks to a slight bump in the compression ratio.

The 6.9 IDI featured oil-cooled pistons, four-bolt mains, a massive forged crank with 2.2-inch rod and 3.1 inch main journals, a gear-driven cam and injection pump, and a whole lot more. Unlike modern diesel engines, it doesn’t feature any sort of direct injection. Instead, it uses a DB2 rotary pump and pintle type injectors. In 1984, International increased the compression ratio a little bit more, which bumped power a little bit more.

The 7.3L IDI

In 1986 International Harvester went through some changes, and from that point on, they’ll be known as Navistar International. In 1988, International gave the 6.9 IDI a complete makeover, and the most important change that they made was an increase in displacement from 6.9 liters to 7.3 liters. They did this by increasing the stroke by 0.18 inches.

They also modified the heads, head bolts, head gaskets, rocker gear, and combustion chambers for more power efficiency and reliability. The glow plug system was also revised, and they topped it off with new tuning, and bam, this new 7.3L IDI produced 180 horsepower and 338 pound-feet of torque. Still gutless by today’s standards, but at least it’s heading in the right direction. In 1992, there was another small bump in power, but all these changes did create some issues.

Most notably, the increased bore and changes to the cooling system resulted in many 7.3L IDI engines experiencing cavitation damage in the water jacket. This issue could be band-aided with some coolant additives, but ultimately the problem became well-known among Ford truck owners with the 7.3 IDI engine.

The 7.3L IDI Turbo

Now, the old saying that diesel engines and turbochargers go together holds some weight, and as you can see up to this point, pretty much all these diesel engines, the 6.9L IDI and the 7.3L IDI, they’re pretty gutless, they’re pretty slow. We’re talking about 180 horsepower and 300 something pound-feet of torque, it’s pretty weak by today’s standards, and really it was kind of weak back then.

Luckily, International and Ford had figured this out, and they introduced the IDI Turbo, which is basically a 7.3L IDI that had a turbocharger strapped to it. The advertised power for this new turbocharged 7.3L was only 190 horsepower and 385 pound-feet, but it’s widely accepted that Ford underrated this engine. You might be wondering why they’d underrate their new turbocharged engine. After all, it could have helped Ford with sales.

The answer is that Ford and International had been working on the new upcoming 7.3L Powerstroke and wanted to make sure that these new Powerstroke engines were better in every single way, even if that meant fluffing up the power numbers by underrating their current engine. That being said, the IDI turbo was marketed pretty well, but Ford had a heavy focus on high altitude performance rather than raw power output.

Internally, the 7.3L IDI turbo received improved head gaskets, modified pistons with larger wrist pins, inconel exhaust valves, new injectors, injection pump calibration changes, and a few other changes. The minimum boost on the IDI turbo was around five psi, with most of these engines producing 8 to 10 psi in stock form when new. Again, by today’s standards, 8 to 10 pounds of boost for a diesel engine is laughable, but you have to remember this was 1993, and back then, things were different.

A good way to think about these early IDI turbo engines is that they are high compression, low boost engine. Now that’s a lot different compared to modern engines, including the 7.3L Powerstroke, which are low compression high boost, which ultimately results in a lot more power and more efficiency. The Turbo IDI and Powerstroke shared sales in 1994 when the Powerstroke was launched mid-year. In reality, this new 7.3L Powerstroke was a lot like the outgoing 7.3L IDI turbo.

Not in the sense that they shared a lot of parts, although they did share a few parts, more that they were clearly related, and you could see some of that inside the engine, where they shared some designs. Up to this point, the relationship between Ford and Navistar International was going really well. There was no reason for anything to go bad.

They had just dropped that new 7.3L Powerstroke, which is making a ton of power. It was better than anything that they had ever dropped before, and they didn’t know it at the time, but the 7.3L Powerstroke, obviously would go on to become arguably the best Powerstroke engine ever. And really, probably the most reliable Powerstroke engine ever.

The 7.3L Powerstroke

Now, while it doesn’t make a crazy amount of power, and it’s known for leaking from basically every crevice on the motor, enthusiasts love the 7.3L. With the move from the IDI turbo engines to the Powerstroke engines, Ford ditched the mechanically driven injection system in favor of electronic injection. Of course, this upsets some enthusiasts who love the simplicity of mechanically driven injection systems, but it’s something Ford and International had to do in order to stay relevant with GM and Dodge.

From 1994.5 to 2003, the 7.3L Powerstroke was a massive success. Ford’s diesel-powered trucks were selling more than ever, with around 2 million 7.3L Powerstroke engines produced from International’s plant in Indianapolis. It’s also worth noting that the 7.3L Powerstroke is nearly identical to the Navistar T444E engine, which was used in a wide range of applications from school buses to tow trucks.

Throughout the years, Ford and International made a few tweaks, and by 2003 the 7.3L Powerstroke was producing 275 horsepower and 525 pound-feet of torque. A far cry from the weak IDI Turbo engine before it. Of course, all good things have to come to an end, and by the time 2003 had rolled around, emissions regulations were stricter than in 1994 when that Powerstroke engine was first released.

Not only that, GM’s LB7 Duramax and the 5.9L common rail Cummins were already up to 300 horsepower or more, meaning Ford was behind the ball on performance with the Powerstroke engine. Really, it was to the point that Ford and International knew that it’d be easier to develop a new engine with emissions in mind rather than trying to make the 7.3L work with the emissions standard. So, that’s where they came up with the 6.0L Powerstroke.

The 6.0L Powerstroke

And interestingly enough, the 6.0L Powerstroke actually began development in the late 1990s when the 7.3L was at its peak and selling like crazy, so Ford and Navistar knew this was going to happen, and they had plenty of time to prepare for it, and develop an engine. But, the 6.0L is basically where all the problems start with their relationship and the start of the downfall between Navistar and Ford.

Before we get into the issues with the 6.0L Powerstroke, we should look at what makes it different from the outgoing 7.3L and why it was supposed to be so much better with all the advancements they had put on it. Key features include the four-valve cylinder heads, quick spooling variable geometry turbo, a lower voltage and higher pressure version of the HEUI injection system, and a crank case bed plate for superb bottom-end strength.

Ironically, a lot of these features that made the 6.0L Powerstrokes such an improvement over the 7.3L actually ended up being troublesome as the miles racked up. Thanks to the success of the 7.3L Powerstroke, you could argue that some of the 6.0’s problems were exasperated. At the time Ford’s super duty trucks were outselling the competition by quite a bit, which continued when the 6.0L was released.

Ultimately meaning mass production from the very start and possibly missing a few key design flaws in the process. By releasing the 6.0L in 2003, Ford was able to meet the 2004 emissions deadline by an entire year in advance. One of the key features to meeting these new stricter emissions regulations was the use of an exhaust gas circulation system. Unfortunately, this has since been known to be a problematic part.

Common issues with the 6.0Ls EGR system are that the EGR cooler accumulates soot, carbon, and grime buildup. That reduces flow and eventually requires cleaning. Lack of coolant flow through the EGR cooler can also cause it to rupture, and the EGR valve is prone to sticking, thanks to the same soot and carbon accumulation that hampers the performance of the cooler.

Another advancement from the 7.3L to the 6.0L was Ford and Navistar’s usage of a variable geometry turbocharger, the Garrett GT3788V8. Now, this VGT works by using electronically controlled vanes inside the exhaust housing of the turbocharger, which allows it to effectively change the size of the exhaust housing. Now, this basically means it can act like a small turbo or a big turbo, and depending on the RPM and load, it can optimize that accordingly.

At low RPM, the vanes remain nearly closed, increasing drive pressure to aid spool up, and at high RPM, the vanes open completely, providing more exhaust flow. While the system was a great way to increase performance, it’s another part on the 6.0L that’s known for failure, from corrosion and or carbon buildup on the unison ring. The next issue on the 6.0L Powerstroke is the head bolts, which are torque to yield.

Now, it’s kind of surprising that this is an issue on the 6.0L Powerstroke considering torque to yield head bolts are used across the automotive world on a bunch of different engines, but they have a fatal flaw, and that’s when they reach their yield point, or they go past their yield point, they are permanently stretched, and they can no longer provide any significant clamping force. <Meaning, once they stretch they’re done.

They’re not going to clamp the head to the block as strong as you need it. Now, on top of that, it’s not just that the head bolts stretch. It’s that there are only four of them per cylinder on the 6.0L, whereas, on the 7.3L, they were using six head bolts per cylinder. Really, in totally stock form, those head bolts aren’t necessarily that big of an issue. It’s when you start to turn things up that they quickly become a failing point and will basically immediately fail.

Obviously, the head bolts themselves aren’t going to fail, but the head lifts, and then your head gasket fails, creating a whole host of other issues. Other major issues include oil cooler problems, high-pressure fuel pump failure, injector failure, and a lot more. Simply put, all these issues had compounded into a slew of warranty claims from Ford truck owners who needed their trucks fixed from these issues.

Navistar International was supposed to help Ford pay for these warranty claims, which is where the lawsuit started in 2007. Ford was mad that Navistar was increasing the price of their engines and claimed they hadn’t been paying their fair share of the warranty claims. Ford claims to have spent over 1 billion in repairs and recalls on the 6.0L Powerstroke.

They also claimed that their contract with Navistar International allows them to debit Navistar’s invoices to recover those repair costs, and in response, Navistar temporarily stopped shipping Ford’s new 6.4L Powerstroke diesel. Speaking of which, the 6.4L Powerstroke diesel is the last stop on this story and where things get even worse. After just four years, Ford and Navistar replaced the 6.0L Powerstroke with the 6.4L Powerstroke, and they really did this replacement for two reasons.

One, the 6.0L Powerstroke, was incredibly problematic. Ford was facing literally hundreds of millions of dollars of repair and warranty claims, so they wanted to get rid of it. This engine was obviously going to cost them a lot of money in repairs, so it needed to go, and two, the emission standards once again came crashing down, and Ford needed something that was going to meet these new emission standards.

The 6.4L Powerstroke

Now, this new 6.4L Powerstroke made 350 horsepower and 650 pound-feet of torque and was believed to be free of all the problems that plagued the 6.0L. However, you’ll end up seeing that they basically just made one of the worst modern production engines ever. The reliability was improved from the 6.0L to the 6.4L, but it still wasn’t up to standards, especially when you look at something like the products from GM and Dodge at the time.

Interestingly enough, the 6.4L and the 6.0L share the same architecture, which you would think Ford would avoid entirely given all the problems with the 6.0L, but it had a good architecture. It just needed better components to stop all the failures. Arguably the biggest news on the 6.4L, was that Navistar International replaced the HEUI injection system with a high-pressure common rail injection system.

This new injection system provided much quieter engine operation and a pretty big bump in power, plus it reduced emission significantly. To push emissions even further, the 6.4L used a second EGR cooler, a more efficient EGR valve, and a diesel particulate filter. More big changes include the addition of a compound turbocharger setup and a fuel cooling system.

One of the more annoying issues of the 6.4L Powerstroke is that it’s physically massive and really crammed into the engine bay, to the point that a lot of simple jobs on the 2008-2010 Ford trucks require the cab to be removed. Now, while removing the cab makes it easy to work on everything, it also adds thousands of dollars to labor costs for any given repair.

Looking at a few of the parts that cause issues on the 6.4L, we’ll start with the diesel particulate filter. This is a piece of exhaust that is designed to collect soot from the exhaust and then burn it off through a regeneration mode. Put simply, the DPF is known for clogging up and failing and then putting the truck into basically a perpetual regeneration mode.

The next issue is the EGR cooler, which is also plagued on the 6.0L Powerstroke, but now on the 6.4L, there are two of them, doubling up the problem. The fuel system is also known for being very problematic on the 6.4L. The piezoelectric fuel injectors have extremely tight tolerances, and if the contaminants get into the fuel system, it’s basically going to kill the injectors.

There’s also the issue of water getting into the system and rusting parts of the injection system, which can take out the injection pump, injectors, and sometimes the entire engine. On top of that, the K16 injection pump is known for failure at any time there’s a lack of low-pressure fuel supply from the lift pump. Really, Navistar International did rush to put this engine together. It was basically just an attempt to salvage a relationship between Ford and them because the 6.0L had been such a failure.

How it Ended

So, they just needed to slap something together that would meet emission standards and fix the relationship, and instead, they put together something that was even worse than the original problem with the 6.0L. Today, the 6.4L is known as a throwaway engine, in the sense that a lot of times, the engine is literally thrown away and replaced with a new one when problems arise because it’s actually cheaper and more effective to just put in a new motor.

Now, if you look around online, basically everyone will tell you that the 6.4L is a total piece of garbage; absolutely stay away from it. There’s literally nothing good about it, the only cool thing about it is that the compound turbocharger is set up to make a lot of power, but other than that, it’s an absolute piece of junk. It is literally probably the worst modern production engine ever.

In fact, it was such a failure that it basically killed the relationship between Ford and International in 2010/2011. But their contract was up around 2011, so it kind of made sense. The relationship just pretty much ended when the contract ended because Ford obviously did not want to renew with Navistar, and instead, Ford actually went out and developed their own engine, which was the 6.7 Powerstroke.

Now, obviously, this was a huge undertaking for Ford to just develop their own diesel engine. They had been relying on Navistar to build these, design, and build these engines, so it was an extremely expensive and risky proposition, but obviously, it worked off paid out in dividends because the 6.7 Powerstroke is still being used today.

Where the 6.0L Powerstroke only lasted four years and the 6.4L only lasted two years, the 6.7 Powerstroke is still being used, and that’s what is that 11 years later, 12 years later, it’s still being used. It’s a far superior platform than anything Navistar had put together for Ford previously, other than maybe the 7.3L. So, that’s where our story ends.

That’s the story of how Navistar almost killed the Ford Powerstroke lineup. It was basically all good up until they released the 6.0L Powerstroke and that was just not a good engine, and then they tried to make it better with the 6.4L Powerstroke, and literally made it worse, and it cost Ford hundreds of millions, I think even a billion dollars in repairs. And that’s a lot of money, so it pretty much almost ended their Powerstroke lineup entirely.

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