6.4L: Long List of Failures

THE BAD, THE WORSE, AND THE UGLY

With its factory compound turbo system, the debut of common-rail injection on the Power Stroke platform, quick-firing piezo injectors, and 350 hp from the factory, the 6.4L definitely had a lot of promise when it debuted in early ’07. Back then, Ford fans who had already been dealing with the 6.0L’s reliability issues for nearly five years were hopeful the 6.4L would be the great savior for the Power Stroke name. Initial impressions were favorable, but as time has worn on and the miles have racked up, the 6.4L has become notorious for a long list of failures. Many of which cost big money to address.

Today, the 6.4L is often referred to as a 150,000-mile proposition, a throwaway engine, or worse: a ticking timebomb. From its leaking radiators and up-pipes to the high-pressure fuel pump’s propensity to self-destruct, to cracked pistons, this engine is plagued by failures both big and small. Appropriately, it’s the rarest to make it to the 200,000-mile mark before facing something catastrophic. But be careful who you say that to… Despite its frequent and well-documented problems, 6.4L owners who haven’t seen this engine’s ugly side tend to swear by it. So what’s the actual verdict? In the following pages, we’ll explore the 6.4L’s most common failure points and let you decide for yourself.

Pull Quote: “Not only are the 6.4L’s replacement components expensive, but the cab has to be pulled for most major repairs, further driving up the cost of labor.”

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Going from bad to worse, and eventually covering the ugly, we’ll kick things off with the inconvenient failure nearly every 6.4L faces at some point in its lifetime: a leaking radiator. The issue occurs when the crimps that hold the aluminum core to the plastic end tanks stretch. This allows the two to separate. Some attribute the crimp failures to the upper radiator support. They say it allows too much flex to occur at the top of the radiator. Regardless, throughout the 6.4L production run, Ford was never able to rectify the radiator problem.

Ford issued several technical service bulletins (TSBs) regarding the leaking radiator issue. One, in particular, called for the installation of a Venturi Tee. According to Ford, it was to relieve coolant pressure spikes within the radiator. As you can imagine, it didn’t solve the leaking issue. According to most shops around the country, the fact that the radiator splits at the aluminum-to-plastic seams is directly related to pour quality from the factory.

Cracked up-pipes are extremely common on the 6.4L. They typically crack at the bellows (or expansion joints). This causes a loss of drive pressure, a drop in boost, and poor drivability. It also leaves a mess of soot all over the firewall and transmission tunnel, and an audible whistle under the cab. Adding insult to injury, accessing the up-pipes means the cab has to go up in the air. We all know battling seized up-pipe bolts is pretty much a foregone conclusion. Needless to say, it’s a fairly involved (and expensive) fix.

As with any after-treatment-era diesel, emissions-control equipment is prone to failure. The 6.4L was the first Power Stroke to come with a diesel particulate filter. Inevitably, a few growing pains followed. Early issues with active regeneration led to excessive heat being built in the DPF. This led to the infamous flaming tailpipe debacle that prompted a recall. Some early production DPFs even leaked soon after leaving the factory. DPF failures are rampant. Be it from filling the wall-flow style catalyst up due to insufficient regeneration operation or faulty sensors.

As a direct result of the 6.4L’s injecting additional fuel on the exhaust stroke during the regeneration process (which is employed to clean the DPF), the diesel that doesn’t make it out of the cylinders slips past the compression and oil rings and ultimately joins the engine oil down in the crankcase. Of course, diluting engine oil with diesel fuel doesn’t bode well for things like main and rod bearings. Nor the turbochargers or valvetrain.

This is why you’ve heard that 6.4L’s “make oil.” The additional diesel that makes it into the crankcase during regeneration eventually adds up to a substantial amount. In fact, it’s not uncommon to drain five to six gallons (20-24 quarts) of oil out of an emissions-equipped 6.4L during an oil change (note: there should only be 15 quarts). After news of the issue became widespread, most owners began following Ford’s severe conditions service interval of 5,000 miles rather than the normal operating conditions’ recommended 10,000 miles.

The 6.4L Power Stroke’s dual EGR cooler and dual poppet EGR valve were definitely an improvement over the hardware used on the 6.0L. Nevertheless, the EGR system still only functions so long before a problem arises. Extended periods of idling (where wet-stacking occurs) can plug the EGR valve in short order and at very low miles. No matter how you drive, the EGR coolers plug up eventually. The horizontally mounted cooler (the one that’s the first to be exposed to exhaust leaving the heads) usually (and predictably) clogs first.

One negative side-effect of the EGR system (there are many more) is the toll it takes on the aluminum front cover. When super-heated coolant returns through the front cover, cavitation occurs (i.e. flash boiling of the coolant). Over time, the cavitation will eat away at the front cover. Eventually, this will cause a hole to develop. Coolant can sneak through to the crankcase and begin contaminating the engine oil.

Blown head gaskets aren’t as frequent with the 6.4L as they were with the 6.0L, but it still happens. If a 6.4L has been tuned for tens of thousands of miles, don’t be surprised to find coolant residue on the degas bottle. Depending on how it’s driven, a tuned 6.4L without head studs can typically survive 80,000 to 100,000 miles on a 300-plus hp file before lifting a head. Of course, that kind of longevity is directly dependent on the way you drive the truck.

So what keeps the head gaskets alive so long as opposed to the 6.0L? Despite the fact that the cylinder heads are virtually identical between the two engines (which includes the use of four head bolts per cylinder), one major difference is that the 6.4L uses a larger diameter (16mm vs. 14mm) and shorter length head bolts. Still, with enough miles racked up in the 600rwhp range, the added cylinder pressure ends up stretching the 16mm bolts.

Like every other engine in the segment, a quality fastener such as the head studs offered by ARP can make blown head gaskets a non-issue. A studded 6.4L can handle big cylinder pressure. Although, weak spots in the block’s casting (on the lifter valley side of the head bolt bores for cylinder numbers 3 and 5, which are in close proximity to water jackets) can crack. This allows coolant to contaminate the engine oil, and essentially trash the block. Most of the issues associated with cracked blocks stem from head studs being over-tightened. Once more engine builders began observing the manufacturer’s recommended torque specs, cracked block cases declined.

To be sure, there is nothing you can do about a thinly cast area of the block. But there are a few insurance measures you can take when installing ARP head studs. First, chase all threads in the block with a 16×1.75mm tap to clean them up. Second, apply ARP thread sealer to the block threads of each stud that protrude into a water jacket. Third, and most importantly, when threading the studs into the block by hand, bottom them out and then back each one off ¼ of a turn (or 90 degrees). During the torquing sequence, the nuts will inevitably turn the studs. This will ensure the studs don’t dig into the block is key.

A major point of wear in the 6.4L valvetrain occurs at the tips of the rocker arms. Unlike the 6.0L, the 6.4L’s rocker arm ends don’t see the same amount of lubrication. Unfortunately, the engine oil can be heavily diluted with diesel fuel. As a result, what little oil the rocker does see isn’t the best lubricant. You end up with excessive ball pivot wear and the “tick” the 6.4L is notorious for. Equally alarming, it’s not uncommon to find each rocker loose when you pull the valve covers.

As the rocker arm’s ball pivot wears, it will begin to gouge into the valve bridge it rides on. Eventually, the ball pivot will wear completely down within its socket at the end of the rocker arm. And just think, while all this disintegration is taking place, those missing pieces are going somewhere…

Cracked pistons are the catastrophe that keeps on giving for the 6.4L Power Stroke. Regardless of power level, this failure can happen at any time during the engine’s lifespan. In most cases, it occurs in higher mileage engines or engines that’ve seen years of accumulative abuse. The fact that no factory short-block is immune to cracking a piston keeps many 6.4L owners on edge, and perpetually uncomfortable.

It might not be quite as bad as cracking the block, but a cracked piston can certainly render the crankcase irreparable. In virtually every case, the crack begins at the thin edge (or lip) of the piston’s fuel bowl. From there, it spreads across the piston, directly above the centerline of the wrist pin. When it comes to pass, white smoke out the tailpipe and excessive crankcase pressure gives the failure away. On top of your mechanic telling you that you’re going to be down a while.

A lot of the 6.4L’s injection system failures can be traced back to water infiltrating the fuel system. Lack of maintenance whereby the water separator seldomly gets drained allows a greasy, white buildup. Known as coagulation, it forms in the collection bowl, which eventually clogs up the drain valve ports.

Coagulation in the water separator effectively limits the assembly’s water-collecting capacity. Sooner or later water slips by and contaminates the fuel system. Once there, water reacts with the metal it comes into contact with and forms rust.

The 6.4L’s tight tolerance injection system doesn’t tolerate contaminants well. As with other high-pressure common-rail systems, the formation of rust within it creates the perfect storm. It often culminates in a colossal, chain-reaction failure of the Siemens K16 VDO high-pressure fuel pump self-destructing and taking out the piezo injectors with it.

Rubbing salt in the wound (as the 6.4L often does), accessing the high-pressure fuel pump calls for pulling the cab. The K16 VDO is gear-driven at the back of the valley and under a dedicated cover. It’s similar to how the HPOP is enclosed on the 6.0L. You’ve got considerable labor (i.e. money) involved in simply removing it. That’s still before forking over the cash for a new or remanufactured pump and everything else to start fresh.

When the K16 high-pressure fuel pump is headed south it typically throws a P0088 code. Unfortunately, when the K16 begins to self-destruct it’s known to send shrapnel through the rails and into the injectors. The cost of replacing the K16, the rails, the injectors, pulling and cleaning the fuel tank, and everything else the job entails typically starts at $6,000 and goes up from there.

In some cases, K16 debris entering an injector can cause it to stick open. This can melt the piston beneath it. Sadly, in these worst-case scenarios—where K16 failure costs the owner his or her short block—many choose to park the truck and walk away once they’ve seen the repair quote. After all, it’s hard to justify putting $15,000 or more in repairs into a truck. Especially if it’s only worth that much on the used pickup market.

This is a more mild K16-related failure, but one that still calls for pulling the cab. It unfolds when the volume control circuit grounds out. It happens when a hole is worn through the wire sheath of the high-pressure fuel pump harness that passes through the cover gasket. When the bare wire makes contact with the pump, it triggers poor performance or a no-start condition, and P0003, P0004, or P0091 codes.

Ford did issue an updated wiring harness that solves the volume control circuit ground problem (PN 8C3Z-9G805-B). However, if you’ve got a 6.4L that was built before August of 2007, you don’t have one of the lucky engines. When this problem strikes, you’re once again pulling or paying someone to pull the cab to perform what is actually a very simple fix at the back of the valley.

FREQUENTLY ASKED QUESTIONS

What is included in the S300 Single Turbo Down Pipe for the 6.4L Powerstroke?

Price: $300.00

When you purchase the S300 Single Turbo Down Pipe for the 6.4L Powerstroke, you are investing in a high-quality, performance-boosting component. Here’s what you can expect:

Premium Down Pipe: Crafted from durable materials designed to withstand high exhaust temperatures and corrosive environments.
Perfect Fitment: Engineered for a precise fit with the 6.4L Powerstroke engine, ensuring easy installation and optimal performance.
Performance Enhancement: Specifically designed to improve exhaust flow, which can lead to increased horsepower and better fuel efficiency.
Components and Attachments: Comes with all necessary mounting hardware and gaskets to ensure a secure and leak-free installation.
Detailed Instructions: Step-by-step guide included to assist with installation, making it feasible for both professional mechanics and DIY enthusiasts.

Why Choose the S300 Single Turbo Down Pipe?

High-Grade Materials: Built to last, using top-of-the-line metals that resist heat and corrosion.
Optimized Design: Improves your vehicle’s exhaust system, allowing it to breathe better and perform at its peak.
Easy Installation: With included hardware and gaskets, you have everything you need to replace your old down pipe without any hassle.

Invest in the S300 Single Turbo Down Pipe to experience an immediate improvement in your vehicle’s performance, efficiency, and overall driving experience.

What is included in the S300 Air Intake for the 2008-2010 6.4L Powerstroke?

The S300 Air Intake kit for the 2008-2010 6.4L Powerstroke is crafted to elevate your engine’s performance and boost efficiency. Here’s a detailed look at what’s inside the package:

High-Flow Air Filter

Top-quality construction: The kit includes a high-flow air filter designed to maximize airflow while ensuring superior filtration.
Reusable and washable: Built for longevity, the filter can be easily cleaned and reused, saving you money on replacements.

Premium Piping

Aluminum tubing: The air intake features polished aluminum tubing known for its durability and sleek appearance.
Mandrel-bent design: This ensures smooth and unrestricted airflow, improving throttle response and horsepower.

Silicone Couplers and Clamps

Robust silicone material: These couplers are resistant to heat and wear, ensuring a secure fit and long-lasting performance.
Stainless steel clamps: Rust-resistant clamps provide a tight and reliable seal, preventing leaks and ensuring optimal air intake pressure.

Comprehensive Installation Kit

Detailed instructions: Step-by-step installation guides make the process straightforward, even for DIY enthusiasts.
All necessary hardware: Bolts, nuts, and other essential components are included, so there’s no need for additional trips to the hardware store.

Performance Enhancements

Turbo response: The optimized airflow directly contributes to quicker turbo spool-up times.
Increased horsepower: Expect noticeable gains in horsepower and torque, enhancing your vehicle’s overall performance.

Key Benefits

Improved fuel economy: With more efficient airflow, your engine breathes better, potentially increasing miles per gallon.
Enhanced engine sound: Enjoy a throatier and more aggressive engine sound as a result of the improved air intake system.

Install the S300 Air Intake for your 2008-2010 6.4L Powerstroke and experience a blend of enhanced performance, improved fuel efficiency, and a more aggressive engine tone.

Why does the 6.4 Powerstroke have poor fuel economy, and what parts can improve it?

The 6.4 Powerstroke engine, known for its impressive power, unfortunately struggles with fuel economy—a common concern among its drivers. The primary issue lies in the diesel particulate filter (DPF), which, although effective in reducing harmful emissions to meet strict environmental standards, significantly hinders fuel efficiency. This is particularly noticeable in stop-and-go city driving where the fuel economy drops further.

How to Improve Fuel Efficiency

Fortunately, there are solutions to enhance fuel economy without sacrificing the necessary emissions compliance:

Cold Air Intake: By allowing more cold air into the engine, this component can improve combustion efficiency, leading to better fuel economy.
Upgraded Intercooler: Enhancing the intercooler can lower the intake air temperature, improving engine efficiency and, consequently, fuel consumption.
Tuner (ECU Reprogramming): Tuning devices can adjust engine parameters to optimize performance. When calibrated correctly, a tuner can improve fuel economy while keeping emissions systems intact.

Investing in these aftermarket parts can help mitigate the fuel economy issues associated with the 6.4 Powerstroke engine, all without compromising the vehicle’s emissions compliance.

What should be done if piston failure is suspected?

If piston failure is suspected, it is advisable to replace all the pistons, along with any other worn components, to ensure a thorough repair and prevent further issues.

What are the symptoms of piston failure?

Symptoms of piston failure include noticeable white smoke emitted from the exhaust, a drop in engine compression, reduced power output, and engine misfires.

What preventative measure can be taken to avoid frequent clogging of the EGR coolers?

Installing a coolant filtration system can help extend the life of the coolant, thus preventing the coolers from clogging as quickly.

How many EGR coolers are present in the 6.4-liter Powerstroke, and why is this important?

There are two EGR coolers in this engine, which is significant because it means there is a higher chance of experiencing issues, as both coolers can potentially become clogged.

What symptoms indicate cracked up-pipes in the 6.4 Powerstroke, and what is the solution?

Cracked up-pipes are extremely common on the 6.4L. They typically crack at the bellows (or expansion joints). This causes a loss of drive pressure, a drop in boost, and poor drivability. It also leaves a mess of soot all over the firewall and transmission tunnel, and an audible whistle under the cab. Adding insult to injury, accessing the up-pipes means the cab has to go up in the air. We all know battling seized up-pipe bolts is pretty much a foregone conclusion. Needless to say, it’s a fairly involved (and expensive) fix.

Symptoms to Watch For

Soot Accumulation: Excess soot in the engine compartment, especially on the firewall or hood, is a telltale sign.
Whistling or Hissing Sounds: You might hear a hissing noise under the hood, indicating a leak.

The Solution

The only effective solution for dealing with cracked up-pipes is replacement. However, don’t settle for factory parts. Instead, look for quality aftermarket options. They often boast superior design and construction, plus many come with lifetime warranties, ensuring a more durable and reliable fix.

By understanding these symptoms and opting for the right replacement parts, you can restore your 6.4L Powerstroke’s performance and avoid future headaches.

Why is it not advisable to use factory parts for replacing cracked up-pipes?

Factory parts may not offer the same level of design quality and durability as aftermarket options, which can lead to recurring issues.

Are there any benefits to using aftermarket parts over factory parts for this issue?

Aftermarket parts often provide superior design, better construction, and may come with lifetime warranties, making them a more reliable choice.

What is the recommended solution for dealing with cracked turbo up-pipes?

The best course of action is to replace the cracked up-pipes with high-quality aftermarket parts rather than factory parts.

What auditory signs might indicate a problem with the turbo up-pipes?

Listen for a hissing noise under the hood while the engine is running, which could signal a leak.

What visual indicators suggest there might be an issue with the turbo up-pipes?

Look for excess soot accumulation in the engine compartment, particularly on the firewall or hood.

What causes oil dilution in the 6.4 Powerstroke engine, and how can it be fixed?

“as a direct result of the 6.4L’s injecting additional fuel on the exhaust stroke during the regeneration process (which is employed to clean the DPF), the diesel that doesn’t make it out of the cylinders slips past the compression and oil rings and ultimately joins the engine oil down in the crankcase. Of course, diluting engine oil with diesel fuel doesn’t bode well for things like main and rod bearings. Nor the turbochargers or valvetrain. This is why you’ve heard that 6.4L’s ‘make oil.’ The additional diesel that makes it into the crankcase during regeneration eventually adds up to a substantial amount. In fact, it’s not uncommon to drain five to six gallons (20-24 quarts) of oil out of an emissions-equipped 6.4L during an oil change (note: there should only be 15 quarts). After news of the issue became widespread, most owners began following Ford’s severe conditions service interval of 5,000 miles rather than the normal operating conditions’ recommended 10,000 miles.”

Understanding the Problem

The phenomenon of oil dilution in 6.4 Powerstroke engines stems from the emissions process designed to clean the Diesel Particulate Filter (DPF). This process involves injecting extra fuel, which does not completely burn off and instead mixes with the engine oil. This mixture compromises the oil’s lubrication properties, affecting critical components such as the main bearings, rod bearings, and turbochargers.

Addressing Oil Dilution

To tackle oil dilution, regular maintenance is key. Here’s how you can mitigate the problem:

Frequent Oil Changes: Follow a more frequent oil change interval, such as 5,000 miles under severe conditions, to manage the diluted oil levels effectively.
Oil Quality: Utilize high-quality oil that meets or exceeds OEM standards to ensure optimal performance and protection.
Monitor Oil Levels: Regularly check oil levels to detect any significant increase, which indicates diesel intrusion.

By understanding the causes and taking proactive measures, you can better protect your 6.4 Powerstroke engine from the adverse effects of oil dilution.

What maintenance practices can help manage oil dilution?

Monitoring the oil levels frequently is crucial to detect any excessive capacity, which can indicate oil dilution. Regular maintenance and oil changes ensure that any excess diesel fuel is removed from the system.

How can oil dilution be fixed or mitigated?

To mitigate oil dilution, it’s important to check and change the oil regularly. Using high-quality oil that meets or exceeds OEM standards, along with quality parts like Motorcraft filters, can also help manage the issue.

Why is oil dilution problematic for the engine?

Oil dilution is problematic because the presence of diesel fuel in the oil reduces its lubricating properties. This can lead to insufficient lubrication of critical engine components, potentially causing damage over time.

What is the nature of the extra fluid during an oil change?

The extra fluid observed during an oil change in a 6.4 Powerstroke engine is diesel fuel, not oil. This occurs due to a specific emissions process that causes fuel to mix into the oil.

What are the additional problems caused by the diesel particulate filter (DPF) in the 6.4 Powerstroke?

Early issues with active regeneration led to excessive heat being built in the DPF. This led to the infamous flaming tailpipe debacle that prompted a recall. Some early production DPFs even leaked soon after leaving the factory. DPF failures are rampant. Be it from filling the wall-flow style catalyst up due to insufficient regeneration operation or faulty sensors.

The DPF on the 6.4 Powerstroke, while initially designed to reduce tailpipe emissions, is notorious for causing additional headaches. Beyond the initial problems of excessive heat and recalls, vehicle owners reported persistent issues, including:

Clogging: Over time, soot and particulates accumulate, leading to blockages that can severely affect performance.
Leaking: As previously mentioned, leaking was a concern right from the start, sometimes occurring shortly after the vehicle left the factory.
Sensor Failure: Faulty sensors can disrupt the regeneration process, causing the system to malfunction and leading to further complications.

Fixing these DPF problems can be both difficult and costly, often necessitating the replacement of multiple diesel parts. However, aftermarket solutions offer a way to circumvent these issues, providing systems that outperform their original counterparts.

Are there any solutions or alternatives to the problems caused by the DPF?

Alternatives such as aftermarket DPF systems are available and may perform better than original manufacturer components.

What is the primary function of the DPF?

The main role of the DPF is to cut down on emissions coming from the exhaust.

What specific problems does the DPF cause?

The DPF can lead to issues such as becoming blocked, leaking, and malfunctioning sensors.

What is the recommended solution to the radiator issue?

To address the radiator issue, it is recommended to upgrade to higher-quality aftermarket parts, such as an aluminum radiator designed specifically for the 6.4-liter Powerstroke engine.

What is the primary cause of the radiator issue?

The primary cause of the radiator issue is the subpar design of the radiator from the factory, which makes it prone to leaks.

Why do cracked pistons occur in the 6.4L Power Stroke engine, and what is the solution?

Understanding and Solving Cracked Pistons in the 6.4L Power Stroke Engine

Cracked pistons are a critical issue in the 6.4L Power Stroke engine, and the root cause boils down to an intrinsic flaw in the piston design. Specifically, cracks tend to form around the lip of the fuel bowl, a weak spot exacerbated by extensive use and high mileage.

Why Does This Happen?

Design Weakness: The piston’s structural integrity is compromised due to its initial design, making it vulnerable to stress and heat.
High Mileage Stress: Engines with significant mileage experience more wear and tear, increasing the likelihood of cracking.
Cumulative Damage: Even minor imperfections in the piston can snowball into more severe defects over time, leading to catastrophic engine failure.

The Solution

Replacement with Aftermarket Pistons:
- Upgrading to tougher, well-crafted aftermarket pistons is the most effective solution. These components are designed to withstand increased pressure and temperatures, preventing cracks from forming.
Preemptive Measures:
- Consider installing these aftermarket pistons before issues arise, especially if the engine is approaching high mileage. This proactive approach can save money and prevent further damage.

While the replacement can be an investment, it is crucial for ensuring the longevity and reliability of the engine. Keeping an eye on the piston condition and opting for robust aftermarket options can significantly mitigate the risk of catastrophic engine failures.

What are the signs of cracked exhaust pipes in the 6.4L Power Stroke engine, and how can they be fixed?

What symptoms indicate cracked up-pipes in the 6.4 Powerstroke, and what is the solution?

Symptoms to Watch For

Loss of Power:A significant decrease in engine power is a strong indicator of an exhaust leak.
Soot Accumulation:Excess soot in the engine compartment, especially on the firewall or hood, is a telltale sign.
Whistling or Hissing Sounds:You might hear a hissing noise under the hood, indicating a leak.

The Solution

The only effective solution for dealing with cracked up-pipes is replacement. Full replacement, especially using aluminized aftermarket hardware, is crucial as these parts provide enhanced durability over factory options. Many aftermarket solutions come with superior design and construction, plus lifetime warranties, ensuring a more durable and reliable fix.

By understanding these symptoms and opting for the right replacement parts, you can restore your 6.4L Powerstroke’s performance and avoid future headaches.

What is the only resolution for cracked up-pipes?

Complete replacement of the affected pipes is necessary to resolve the issue.

What is the recommended type of replacement hardware?

It is advisable to replace the cracked pipes with aluminized aftermarket components for improved durability.

What is the auditory sign associated with this issue?

A hissing sound emanating from the engine area can signal a cracked exhaust pipe.

What are the visible signs of an exhaust leak?

Look for soot accumulation on the firewall or underneath the hood, particularly in models from 2008 to 2010.

What is a key performance symptom of cracked exhaust pipes?

A notable decrease in engine power is often a strong indicator of an exhaust leak in the 6.4L Ford Power Stroke engine.

What are the top five common problems with the Ford 6.4L Power Stroke engine?

“Today, the 6.4L is often referred to as a 150,000-mile proposition, a throwaway engine, or worse: a ticking timebomb. From its leaking radiators and up-pipes to the high-pressure fuel pump’s propensity to self-destruct, to cracked pistons, this engine is plagued by failures both big and small. Appropriately, it’s the rarest to make it to the 200,000-mile mark before facing something catastrophic. But be careful who you say that to… Despite its frequent and well-documented problems, 6.4L owners who haven’t seen this engine’s ugly side tend to swear by it. So what’s the actual verdict? In the following pages, we’ll explore the 6.4L’s most common failure points and let you decide for yourself.

Leaking Radiator

Going from bad to worse, and eventually covering the ugly, we’ll kick things off with the inconvenient failure nearly every 6.4L faces at some point in its lifetime: a leaking radiator. The issue occurs when the crimps that hold the aluminum core to the plastic end tanks stretch. This allows the two to separate. Some attribute the crimp failures to the upper radiator support. They say it allows too much flex to occur at the top of the radiator. Regardless, throughout the 6.4L production run, Ford was never able to rectify the radiator problem.

Ford issued several technical service bulletins (TSBs) regarding the leaking radiator issue. One, in particular, called for the installation of a Venturi Tee. According to Ford, it was to relieve coolant pressure spikes within the radiator. As you can imagine, it didn’t solve the leaking issue. According to most shops around the country, the fact that the radiator splits at the aluminum-to-plastic seams is directly related to poor quality from the factory.

Poor Fuel Mileage

It’s safe enough to say nobody enjoys poor fuel economy. The 6.4L suffers while driving in traffic or at slow speeds, mostly due to the diesel particulate filter’s (DPF) demand for fuel during regeneration. The more frequently these regeneration events happen, the worse the fuel mileage becomes. While it’s difficult to recommend methods to counter this without veering into illegal territory, optimizing intake airflow with CARB-approved systems and ECM calibration can provide some relief.

Fuel in Oil

As a direct result of the 6.4L’s injecting additional fuel on the exhaust stroke during the regeneration process (which is employed to clean the DPF), the diesel that doesn’t make it out of the cylinders slips past the compression and oil rings and ultimately joins the engine oil down in the crankcase. Of course, diluting engine oil with diesel fuel doesn’t bode well for things like main and rod bearings. Nor the turbochargers or valvetrain.

This is why you’ve heard that 6.4Ls “make oil.” The additional diesel that makes it into the crankcase during regeneration eventually adds up to a substantial amount. In fact, it’s not uncommon to drain five to six gallons (20-24 quarts) of oil out of an emissions-equipped 6.4L during an oil change (note: there should only be 15 quarts). After news of the issue became widespread, most owners began following Ford’s severe conditions service interval of 5,000 miles rather than the normal operating conditions’ recommended 10,000 miles.

Cracked Pistons

Cracked pistons represent one of the more severe problems for the 6.4L, with poor piston design being the primary culprit. Cracks develop at the lip of the fuel bowl, and although it can happen to any engine, high-mileage powerplants are particularly susceptible. This issue can be a precursor to even more catastrophic failures, and the only repair is to replace all eight pistons with aftermarket options—a costly endeavor.

Cracked-Up Exhaust Pipes

A significant loss of power is another telltale sign of exhaust leaks. Finding soot on a 2008 to 2010 rig’s firewall or beneath the hood, and hearing a hiss coming from the engine area typically means one or both up-pipes is or are cracked. Full replacement, preferably with aluminized aftermarket hardware, is the only resolution.

By understanding these key issues, you can grasp why the 6.4L Power Stroke has garnered its infamous reputation, and you can better prepare for the necessary interventions to keep your engine running smoothly.

What are the preventative steps mentioned to avoid these issues?

Preventative measures include adding a core-support brace for the radiator, optimizing engine airflow, and maintaining a regular maintenance schedule at 4,000- or 5,000-mile intervals to monitor oil levels and prevent fuel dilution.

How common are these problems?

The leaking radiator and fuel in oil are prevalent issues affecting nearly all 6.4L Ford Power Stroke engines. Poor fuel mileage and cracked pistons are also frequent, particularly in high-mileage engines. Exhaust leaks are common, as indicated by the frequent occurrence of cracked up-pipes.

What are the recommended solutions or preventative measures for each problem?

The leaking radiator should be replaced with a high-quality aftermarket aluminum version. Improving fuel mileage involves optimizing intake airflow with approved systems and tuning, along with adding an aftermarket lift pump. Regularly checking oil levels and performing maintenance at shorter intervals can help prevent damage from fuel in oil. Replacing pistons with aftermarket options is the solution for cracked pistons. Exhaust pipe issues require a full replacement with durable aftermarket parts.

What are the consequences of each problem?

A leaking radiator can cause severe engine overheating and damage. Poor fuel mileage results in increased fuel costs and inefficiency. Fuel in the oil can lead to significant internal engine damage. Cracked pistons can trigger catastrophic engine failures. Exhaust leaks result in power loss and potential damage from soot accumulation.

What are the specific causes of each problem?

The leaking radiator is caused by engine vibrations and inadequate bonding between the core and plastic tanks, leading to cracks. Poor fuel mileage stems from the diesel particulate filter’s fuel requirements for regeneration. Fuel entering the oil system is a result of diesel injection during the exhaust stroke, which mixes with the engine oil. Cracked pistons are due to flawed piston design, particularly at the fuel bowl lip. Exhaust leaks occur because of cracks in the up-pipes.

How does a leaking radiator affect the 6.4L Power Stroke engine, and what is the recommended solution?

A Common Problem with Serious Consequences

The leaking radiator isn’t just an inconvenience; it can lead to severe engine damage due to overheating. The separation of the core and plastic tanks, often exacerbated by engine vibrations, allows coolant to escape. This can compromise the engine’s ability to maintain optimal temperatures, risking costly repairs or even engine failure.

A Common Problem with a Clear Solution

If you see a puddle of coolant underneath your 6.4 truck, it’s probably not a blown head gasket. This engine is notorious for developing a leaky radiator due to its flawed factory design. The most effective solution is to replace the factory radiator with a higher-quality alternative. Aftermarket options, such as an aluminum 6.4-liter Powerstroke radiator, offer improved durability and reliability. These parts are specifically designed to address the weaknesses of the original radiator, ensuring a long-lasting fix for the persistent leaking issue.

To prevent further issues, consider adding a core-support brace. This step can be taken before or after a radiator failure and helps stabilize the radiator, reducing the stress on those vulnerable joints.

By upgrading to a better radiator and taking preventative measures, you’ll not only solve a recurring problem but also enhance the overall performance and longevity of your vehicle’s cooling system.

What preventative measures can be taken?

Installing a core-support brace can help prevent the radiator from failing by providing additional stability, either before or after any leaks occur.

What are the potential consequences of a leaking radiator?

If not addressed, a leaking radiator can lead to severe engine damage due to overheating, putting the entire powertrain at risk.

What causes the radiator to leak?

The leaks are primarily caused by engine vibrations and inadequate bonding at the connection points between the plastic tanks and the radiator’s core.

Why is the 6.4L Power Stroke engine considered problematic compared to other Ford diesel engines?

The core of the 6.4L’s problems lies in two significant areas: a fundamentally poor design and the premature failure of emission-control devices. These flaws have led to a myriad of issues that are both costly and complex to resolve. The design shortcomings mean that the engine struggles to maintain reliability, while the emission-control devices, introduced as new technology at the time, often fail long before anticipated.

The expectations set by its advanced features quickly gave way to the harsh reality of its limitations. The lion’s share of issues stem not just from component failures but from an overarching design that wasn’t built to last. This combination makes the 6.4L a notorious chapter in the history of Power Stroke engines, highlighting the cost of innovation without longevity.

How do these issues differ from typical engine problems?

These issues are distinct because they stem from design flaws and premature failures of emission-control devices, which should have had a longer lifespan, rather than typical wear and tear or maintenance-related problems.

What are the fundamental causes of the 6.4L Power Stroke engine’s problems?

The core issues with the 6.4L Power Stroke engine arise from its flawed design, which has led to various components failing sooner than expected, particularly its emission-control systems.