The 6.4L Powerstroke diesel engine was first introduced in 2008 for use in Ford’s Super Duty trucks including the F-250, F-350, and F-450. The turbocharged diesel engine was capable of producing 350 horsepower and 650 lb-ft of torque.
But is the 6.4 Ford diesel any good? Sad to say, it isn’t a very good engine. Ford discontinued its use just two years after.
If you happen to own a vehicle that has this engine under the hood, you better get yourself acquainted with the issues plaguing it. So, what are the common 6.4L Powerstroke problems? Here are 15 of them. We know it’s a lot. But as consolation, we’re including some of the ways you can fix these issues.
1. DPF Traps Soot
The 6.4L Powerstroke is the first Power Stroke engine to feature a diesel particulate filter (DPF). It’s designed to reduce emissions from the exhaust. Paired with Ford’s active regeneration system, the use of the DPF was meant to meet tightening emission regulations at the time of its release. Unfortunately, the initial implementation of the DPF and the regeneration system was quite crude, resulting in poor fuel economy. Many of the issues in this list actually involve these systems.
The DPF in the 6.4L Powerstroke can clog over time due to some fault or failure in the active regeneration process. A clogged DPF can decrease engine performance and affect fuel efficiency.
How to Fix: To prevent DPF from clogging, make sure to use the recommended engine oil during regular maintenance and ultra-low sulfur diesel for fuel. A severely clogged DPF would require either manual cleaning or replacement.
2. Emission Problems
Some 6.4L Powerstroke owners have reported emission issues with their vehicles such as light smoke coming out of the exhaust. Often, problems are caused by poor maintenance. A more severe symptom is the form of heavy visible smoke coming out of the exhaust pipe. Usually, the smoke is thick and white. This is often related to either the DPF issue or exhaust gas recirculation (EGR) components. Sometimes, a clogged DPF can even cause strange odors to emanate from the engine bay.
How to Fix: Routine maintenance should prevent this. Replacing air filters and spark plugs help the engine burn fuel cleaner. If the symptoms are more severe, have a qualified mechanic check the condition of your DPF and your EGR systems. Replace components that are found to be faulty.
3. Poor Fuel Economy
There’s no denying it. The 6.4L Powerstroke is a guzzler. In the Ford F-250, the engine can only get 10.3 MPG. With age and wear and tear of parts and components, you will most likely get worse fuel economy with fewer miles from a gallon of diesel.
How to Fix: We can’t preach having regular and proper maintenance performed on your engine enough to prevent many of the 6.4L Powerstroke problems. That said, you can also try modifying your driving habits to get more value out of your gas money. Don’t mash the gas pedal only to brake suddenly in stop-and-go situations. Avoid idling for long periods of time unnecessarily.
4. Faulty EGR System
Aside from the DPF, the 6.4L Powerstroke’s EGR system is also suspect, particularly the EGR valve and the coolers. The coolers are meant to lower the exhaust gas’ temperature after getting rerouted by the EGR valve. The kicker? This diesel engine doesn’t have just one EGR cooler. It has two. And either can get clogged or break down over time. A common sign is having white smoke coming out of the exhaust pipe.
How to Fix: First, check the EGR valve. If you have excess moisture or coolant around the valve or in the housing, it’s likely that the valve has gone bad. Next, check the condition of your coolers. Replace these if needed. Some owners even just do away with the entire EGR system but know that your vehicle may not pass emission standards. Depending on where you are, check if this is even a legal option.
5. Leaking Radiators
Powerstroke engines have a history of coolant leaks. The 6.0L version spewed coolant due to blown head gaskets. For the 6.4L Powerstroke, however, leaking radiators are often the cause. The OEM factory radiator was constructed with a combination of plastic and metal parts. The crimps on the plastic ends tend to get undone. Once a gap forms, coolant then leaks. If your coolant levels decrease drastically, see coolant puddles underneath the engine bay, or if your truck tends to overheat, have your radiator checked for leaks.
How to Fix: The best remedy is to replace the OEM radiator with a better aftermarket one. Aftermarket parts don’t have the design faults of the original part from Ford.
6. Up-Pipe Expansion Joints Crack
If you’ve already noticed, there’s really plenty of issues concerning the 6.4L Powerstroke’s exhaust system. The expansion joints in the exhaust up-pipes can crack due to the repeated heating and cooling (which is part of the exhaust system’s nature) and excessive vibrations. The up-pipe connects the exhaust manifold to the turbocharger. Cracks in the expansion joints can lead to hissing noises and loss of power due to the erratic flow of gasses into the turbo.
How to Fix: If you experience any of these symptoms, check the expansion joints. This can be tricky to check on the OEM factory part since it has a mesh construction. As an alternative, you can go for aftermarket parts that have the more solid bellow or accordion construction. Make sure you also get new gaskets when replacing the up-pipe.
7. Problematic Oil Cooler
What makes the 6.4L Powerstroke a nightmare to fix is that some symptoms may be caused by different issues. While it’s a good rule of thumb to explore the DPF and EGR systems first, your issue might be coming from yet another faulty part. The 6.4 Powerstroke also has a problematic oil cooler. You may experience some power loss or degraded engine performance if your oil is running too hot. Compare your coolant and oil temperature levels. If there’s 15 degrees or more difference between the two, it’s likely that the oil cooler is going or has gone bad. It’s common for the oil cooler to clog up.
How to Fix: The problem with the Power Stroke oil cooler is that it can’t be cleaned. You can either get an OEM or aftermarket oil cooler to replace the faulty on in your diesel engine.
8. Residual Fuel in the Oil System
Ideally, the fluids that cycle through your engine like the coolant, oil, and fuel shouldn’t mix. But there are times when fluid from one system gets into the other. Fuel, for example, can enter the crankcase. This happens when the fuel isn’t fully burnt off during combustion.
How to Fix: This can be fixed by performing an oil change during the recommended intervals. You can also have an engine oil flush but avoid doing this with every oil change.
9. Cracked Pistons
Another problem stemming from poor design is cracking pistons. The 6.4L Powerstroke pistons are designed to have a bowl which is common for diesel engines. However, the OEM pistons in this Ford diesel engine is poorly designed that these bowls can be the ones to cause cracks. Once a fissure forms in this area, the crack can then run the entire length of the piston. An engine with a cracked piston will not perform well due to loss of compression. You may also experience knocking or vibrations.
How to Fix: A qualified mechanic can check the condition of your pistons. To fix them, you can replace them with aftermarket pistons which don’t suffer from the design fault of the OEM part.
10. Cylinder Washing
Cylinder washing is similar to what happens when fuel gets into the oil system. However, in this case, it’s caused by the active regeneration system. Diesel fuel gets injected late in the engine’s exhaust stroke. Since the fuel doesn’t get burnt, it “washes” the cylinder. The oil layer protecting the engine gets stripped off by the diesel. Unlubricated parts are subject to friction damage.
How to Fix: Unfortunately, this one’s just one of the innate problems with the 6.4L Powerstroke. Frequent oil changes should help ensure that the lubrication is in optimal condition to protect the engine.
11. Water in the Separator
Engines are equipped with a fuel-water separator. It’s basically a filter that ensures that only clean diesel is sent to the engine. In the 6.4L Powerstroke, the fuel-water separator can get clogged, which means it can’t effectively filter out moisture. Once there’s excess water in the system, it can also get into other components and encourage corrosion to form. It can damage fuel injectors, the injection pump, and other parts. Sludge can even form in the separator’s drain valve sticking it shut.
How to Fix: To prevent failure, you have to drain the fuel-water separator frequently. An aftermarket solution is to install a fuel lift pump kit which has better filters than the factory separator.
12. Wiring Chafe
Wiring chafe happens when the electrical wires’ insulation get stripped off. It isn’t a unique thing to the 6.4L Powerstroke. Many vehicles can experience them. Excessive vibrations can cause wires to rub against other parts, taking off the insulation. Heat cycles can also cause the insulation to crack and fail. Age also degrades wiring insulation. With this Ford engine though, it’s the wiring at the high pressure fuel pump that often suffers from heavy chafing. Exposed wires can lead to shorts or disconnection. Without the high pressure fuel pump working, fuel won’t reach the engine and the engine will stall or not start.
How to Fix: This is a known issue and Ford already rolled out a solution with a new wiring harness part that has a protective piece to prevent further chafing from happening.
13. Front Cover Cavitation
The 6.4L Powerstroke is prone to cavitation of the front cover. Without getting into the advanced physics of it, air pockets can form inside the engine’s cooling system which creates some form of turbulence inside. When they happen repeatedly and quickly, they can result in the development of holes or cavities. In the case of the 6.4L Powerstroke, the area often affected is the front cover. Having holes in the front cover can cause coolant to leak out.
How to Fix: This can be prevented by following Ford’s prescribed cooling system flushing intervals. Another option is to use special coolant additives.
14. Oil Dilution
When changing the oil in your 6.4L Powerstroke, there may be times when there seems to be an excess of lubricant that’s drained from the system. You typically need 15 quarts or 14.2 liters of engine oil for a routine oil change. But what you drain out can be much more. This is a sign of oil dilution. What’s mixed with your oil is diesel. This phenomenon is very much related to the engine washing and active regeneration issues. The extra diesel ends up getting mixed with the rest of the engine oil. Diluted engine oil doesn’t perform well, resulting in higher temperatures and the degradation of the engine.
How to Fix: Since the causes of engine oil dilution are pretty much latent to this Power Stroke engine, you may just have to live with it. Make sure that you use the recommended diesel engine oil and perform maintenance at regular intervals.
15. Wear Issues with the Rocker Arms
In an engine, the rocker arms are parts of the valve train which transmit camshaft movement towards the intake and exhaust valves. The rocker arms in the 6.4L Powerstroke are notorious for wear issues. When a rocker arm pops off, you may hear a loud popping noise coming from the air intake side of the engine. The engine can still perform but there will be that noticeable pop or misfire from the cylinder with the faulty rocker arm.
How to Fix: A mechanic can remove engine cover and check the condition of the rockers for wear. To prevent excessive wear on the rocker arms, make sure that you change your oil frequently.
6.4 Powerstroke Reliability: Is It Worth the Risk?
Is the 6.4 Power Stroke a reliable engine? Not really. As you can see, this is quite a lengthy list of issues concerning this Ford diesel engine.
Considering that the model years of Ford trucks that used this engine are already more than a decade old, purchasing a used vehicle with this engine may not be worth it.
If you’re wondering how many miles will a 6.4 Power Stroke last? It’s supposed to be rated for 150,000 to 200,000 miles. But with these issues, a number of Super Duty owners have found themselves swapping engines well before the engine’s supposed to go out.
But if you already own one and want to keep the vehicle for whatever reason, it would be wise to keep the truck properly maintained. There are ways to “bulletproof” the engine with aftermarket parts and modifications but these can be quite expensive.