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Common 6.4L Powerstroke Problems & Their Solutions

Most Common Issues 6.4L Powerstroke Owners Encounter

While the 6.4L Powerstroke offered some improvements over the 6.0, they still frequently encounter problems. Most of these problems can be attributed to the new 6.4L Powerstroke’s emissions systems. They did successfully reduce tailpipe emissions but the early designs of the DPF and EGR system are flawed at the very least. Emissions have improved over the years as Ford’s latest 6.7L Powerstroke experiences dramatically lower emissions system failures. There are other 6.4L Powerstroke problems that are unrelated to the emissions devices though. Leaking radiators and cracked up-pipes are also common issues. If you want to know all of the most common 6.4L Powerstroke problems, keep reading. We’ll also give you our recommendations for preventing them, and solutions to make sure these problems never happen again!

Oil Dilution

Oil dilution is an extremely common problem that 6.4L Powerstroke owners face. Have you ever changed your engine oil on your 6.4 by yourself? You might have been surprised that after draining the oil out of your truck. Quarts and sometimes even over a gallon of extra oil can be removed when changing your engine oil. It’s not really oil though. What you’re experiencing is oil dilution. That extra liquid is diesel fuel. When your 6.4 undergoes active regeneration, diesel is injected late in the exhaust stroke. It then travels into the exhaust stream, elevates EGTs and burns off hydrocarbons from the diesel particulate filter.

Oil dilution is an unfortunate by-product of the process. Why is Oil dilution a problem? Diesel doesn’t offer the same lubricating properties as your engine oil does. This can lead to increased wear and tear on crucial engine components. Cylinder washing can also occur. Cylinder washing is when the fuel removes the thin layer of coil coating the cylinders. While Oil dilution is a major problem, you don’t have to be a victim to it.

The Fix For Oil Dilution

First and foremost, check your engine oil frequently. Once a week take a look at your dip stick. If you’re over max oil capacity, change the oil and oil filter immediately. Don’t use the 10,000 oil change intervals recommended by your owner’s manual. Stick to a severe service schedule when it comes to maintenance on your 6.4L Powerstroke. Use high quality Oil that meet or exceeds OEM specs. You can find our recommended 6.4L Powerstroke engine oil here.

Leaking Radiators

Unlike the 6.0L Powerstroke, a puddle of coolant underneath your truck isn’t because of a blown head gasket. 6.4L Powerstrokes are notorious for developing radiator leaks because of the poor radiator design. The crimps on the ends of the radiators tend to separate, causing the ends to leak.

The Solution for a 6.4L Powerstroke Leaking Radiator

Unfortunately, there isn’t a fix for this other than replacing the radiator. Even if your stock radiator hasn’t failed yet, it’s a good idea to be proactive. Mishimoto’s aftermarket aluminum radiator is a perfect solution for the problem. They even have an additional support bar that helps reduce front end flex to protect your radiator!

Poor Fuel Economy

6.4L Powerstroke fuel economy is terrible. The major reason for the 6.4’s lack of mpgs is none other than the new diesel particulate filter. Active regeneration uses diesel to increase EGTs and clean the dpf. Unfortunately, that’s diesel fuel being used for something other than propulsion. City driving and driving in heavy traffic make mpgs go down ever further as they will result in more frequent active regeneration cycles.

Getting Higher MPGs in a 6.4L Powerstroke

If you want to improve fuel economy in your 6.4L Powerstroke you’re going to have to spend some money. While a straight pipe exhaust and a tuner will greatly increase your mpgs, deleting or turning off emissions devices is federally illegal. Instead, you’re going to want to invest in aftermarket accessories like a cold air intake, aftermarket intercooler, and a programmer or tuner that doesn’t delete your emissions devices. Many tuners are now CARB approved and emissions compliant. Check out our favorite 6.4L Powerstroke performance upgrades here!

Clogging Diesel Particulate Filter

The primary responsibility of the diesel particulate filter is to capture unburnt hydrocarbons before they exit the tailpipe. While the DPF does this successfully, over time the filter can get clogged. This occurs more frequently in early DPF systems that use the post-injection style active regeneration. While a clogged filter doesn’t sound very severe, removing and cleaning the DPF is very labor intensive. They’re very expensive to replace too!

Solution to Clogged DPF

When your DPF is clogged, most likely your truck will derate. Your speed is limited and overall performance is a fraction of what it normally is. This needs to be taken care of immediately. If you are experiencing frequent diesel particulate filter problems, consider in investing in an aftermarket 6.4L Powerstroke DPF from Bully Dog. They’re more efficient than the stock dpf and way easier to work on. They can be removed and cleaned easily and everything is bolt-on. Bully Dog claims some impressive performance improvements from their DPF upgrade too!

Cracked Up-Pipes – Soot on Firewall

Is your 6.4L Powerstroke experiencing excessive soot in the engine compartment? Is there soot on the firewall or the hood area? Can you hear a loud hissing noise from under the hood? A very common issue with the 6.4 is cracking up-pipes. The cracking occurs on the expansion joints and can cause a huge loss of power.

Solution to Cracked Up-Pipe Expansion Joints

Unfortunately, your only option with cracked up-pipes is to replace them. Don’t go with another set of factory up-pipes though! There are plenty of aftermarket up-pipes that offer superior construction and even life-time warranties. Check out these Up-Pipes from Rudy’s Diesel or MBRP.

Clogged EGR Coolers

The 6.4L Powerstroke’s EGR Coolers reduce the temperature of hot exhaust gases after they are re-routed by the EGR valve. Coolant is used in this process which over time can break down, clogging the EGR cooler. Similar to the 6.0L Powerstroke, 6.4s experience EGR Cooler failure often. Unfortunately, the 6.4L Powerstroke has two EGR coolers than can fail! That’s twice the headache!

Preventing Clogging EGR Coolers

As a preventative measure, invest in a coolant filtration system. Mishimoto and Sinister Diesel both make relatively cheap kits that extend coolant life. Make sure you also follow a severe maintenance schedule too. By changing your coolant frequently, you can reduce the amount of problems down the road. Aftermarket EGR Coolers can also offer superior performance compared to factory ones.

Mishimoto Coolant Filtration System 6.4L Powerstroke
Using a coolant Filtration system like the Mishimoto Coolant filtration kit pictured above can help extend coolant life! Plugged EGR Coolers are one of the most common 6.4L Powerstroke Problems.

High Pressure Fuel Pump Wire Chafing

Early model year 6.4L Powerstroke are susceptible to chafing on the high pressure fuel pump harness. Over time, vibrations can cause the wires to be exposed. Once exposed, you run the risk of shorting your high pressure fuel pump. That’s an expensive repair you don’t want to risk! Luckily there is an easy solution.


If you have a late model 6.4, you don’t have to worry about this issue. Ford was well aware of this problem. They corrected this problem in late model trucks by adding a protective covering to the wire harness. If the wires on your HPFP are exposed, purchase Ford’s replacement harness. It’ll come with a protective covering so you won’t have the same problem again.

Front Cover Leaks

Front cover leaks can develop overtime, which can cause coolant to leak into the crankcase. This is another reason it is very important to check your dipstick frequently. You can often catch a problem before it leads to a total engine rebuild. Frequently, leaks develop near the water pump area. Many believe these leaks occur due to cavitation.


If you have a front cover leak, you will have to replace it. It won’t be a cheap repair either. The best thing you can do is be vigilant about your 6.4L Powerstroke’s maintenance. Get a coolant filtration device. Invest in quality coolant and the proper SCA/DCA coolant additive.

Fuel-Water Separator Problems

Add one more part to your list of things that clog on the 6.4L Powerstroke! The fuel-water separator can clog if you don’t drain it frequently enough. Because of the high pressure fuel system used in these trucks, they are extremely susceptible to fuel system failures. If your fuel-water separator clogs, eventually it’ll get to a point where water is allowed to reach your fuel system.


Don’t wait for your fuel filter change interval to drain your fuel-water separator. Try and drain your fuel-water separator at least once a month! If you have significant build-up, you can clean it out manually!

Other 6.4L Powerstroke Resources

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Founder of Diesel Resource and a complete diesel head. Has a little bit of problem buying too many trucks. Learn more about him by checking out his truck.