The 6 Most Common Ford 6.4 Powerstroke Engine Problems

The 6.4 Powerstroke only had a few short years in Ford trucks, in part due to new emissions restrictions but also in part to its mediocre reliability. While it did receive a few improvements over the previous 6.0 Powerstroke, the 6.4 is still prone to a number of common problems, and a few major ones at that.

The 6.4 Powerstroke is known to experience issues the DPF system, oil cooler, radiator, up-pipes, and pistons. We’re going to discuss each of these problems in-depth and provide some thoughts on overall reliability based on our experience owning a few of these in the past.

Ford 6.4 Powerstroke Common Problems

• Leaking Radiator
• DPF Failure
• Up-Pipe Cracking
• Clogged Oil Cooler
• Fuel Dilution
• Cracked Pistons

1) Radiator Leaks

If you notice a puddle of coolant under the 6.4 Powerstroke the radiator is the likely culprit. The plastic ends of the radiator tend to crack or separate and develop leaks. The radiator usually lasts approximately 100,000 miles before issues start to arise. However, improper maintenance and care like letting the engine overheat can cause to the radiator developing issues sooner.

If too much coolant is lost you may start to experience rapid overheating. In this case, it’s important to shut the engine down quickly to avoid further damage. Either way, a radiator leak should be treated as an urgent and important repair. This is especially true if you have a severe radiator leak. Overheating can lead to major internal components like the pistons and valves warping which will require a full engine rebuild.

Radiator Leak Symptoms

• Visible coolant leaks
• Overheating
• Steam from engine bay

It’s normally pretty straight-forward to notice a leaking radiator. Look for any visible leaks under the truck. You may also notice steam from the engine bay if coolant is leaking onto hot parts. Lastly, overheating can occur rapidly if the coolant loss is severe enough.

Replacement Options

If you intend to keep your truck for the long-term we highly recommend upgrading the radiator. Mishimoto radiators are a common option for the 6.4 Powerstroke. However, at nearly $900 they’re certainly not cheap. You can also go for the OE radiator or alternative aftermarket options. Those can set you back about $200-500 depending on the exact radiator. Labor is generally about 2 hours for the radiator so add in a couple hundred bucks for that. All in all, replacement costs for the radiator can run about $400-1000+.

An upgraded radiator can go a long way in reducing EGTs and improving reliability, especially if you do a lot of heavy towing. Therefore, we generally recommend spending a few hundred extra bucks to get a performance radiator if you work your truck pretty hard.

2) DPF Clogging

Diesel particulate filters (DPF) have been problematic parts on many modern diesel engines, and the 6.4 Powerstroke isn’t an exception. This was the first diesel truck from Ford to use a DPF. A DPF is meant to capture particulates before they exit the exhaust. This helps improve emissions, however it also leads to headaches with the filter clogging.

The commonality of this problem leads a lot of people to delete the DPF. It can cause a number of issues once the filter becomes too clogged. DPF clogging is also harder on the engine and turbo. This is because a clogged DPF can cause excess back-pressure. The engine then has a harder time getting rid of hot exhaust gases, which can increase stress on many parts.

Symptoms of a Clogged DPF Filter

• Power loss
• Long crank
• Fault codes

As the filter clogs the engine will experience a lot of extra back-pressure. This often results in power loss as the engine struggles to remove exhaust gases quickly. You may also notice long cranks or receive fault codes indicating an issue.

Cleaning or Deleting the DPF

If you’re DPF is clogged there are a few viable solutions. Often pulling the filter out and cleaning it is the cheapest solution. Though, that won’t stop the DPF from potentially clogging again shortly after. That’s a big reason many owners decide to completely delete the DPF. However, deleting the 6.4 Powerstroke DPF may cause legal and emissions testing concerns. Aftermarket diesel particulate filters are another option, but they can be pretty pricey.

3) Up-Pipe Problems

The exhaust up-pipe is another common problem on Ford 6.4 Powerstroke engines. Up-pipes connect the exhaust manifold to the turbo. It passes exhaust gases to the turbo which are then used to help the turbo produce boost. Expansion joints on the up-pipes are prone to cracking, especially with age and mileage. The cause of the issues usually boils down to vibration and heat cycles.

Up-pipes are a pretty simple but important part of the exhaust system. When an up-pipe develops a crack it creates an exhaust leak and can cause excess diesel soot buildup and also cause the turbo to spool more slowly which puts added stress on the turbo. When the joints crack they can cause excessive soot in the engine bay. You’ll also likely notice a loud hissing noise from the engine bay. This is a pretty simple problem on the 6.4 diesel, so we’ll leave it at that.

Failure Symptoms

• Hissing from engine bay
• Excessive soot in engine bay
• Slow turbo spool
• Power loss

When the joints crack and begin leaking you’ll typically hear a hissing sound and notice lots of soot building up in the engine bay. You may also experience some power loss.

Upgrading or Replacing the Up-Pipe

It’s a good idea to upgrade to aftermarket pipes once the stock ones give out. Otherwise, you may be back in there fixing the same problem a few years down the road. You can find some solid options for the 6.4 diesel like this for under $400. Labor can be a hassle so it’s definitely a good idea to upgrade to up-pipes that won’t run into the same problems.

The factory up-pipes are pretty restrictive and not performance oriented. Upgrading the up-pipes will improve exhaust flow and increase turbo spool. However, the EGR system is connected to the stock 6.4 Powerstroke EGR which makes it common to do an EGR delete while upgrading the piping.

4) Oil Cooler Clogging

As with the DPF, oil coolers are another problematic area due to clogging. Sometimes EGR failures are incorrectly diagnosed, and the real issue at hand is a clogged oil cooler. The 6.4 Powerstroke oil cooler is responsible for cooling the engine oil – exactly as the name sounds. An oil cooler is similar to a radiator or intercooler that has a bunch of passages inside it that funnel oil around. It uses coolant in separate passages to cool the oil, and those passages may become blocked over time. When this occurs the engine oil temps may rise higher than normal.

Keep an eye on your engine oil and coolant temperatures. The two should typically remain within about 15 degrees of each others. If you notice the 6.4 Powerstroke temps are deviating too much chances are the oil cooler is on its way out. There’s no way to clean the oil cooler once it clogs, so complete replacement is usually required.

Symptoms

• Oil/Coolant temp deviation
• Oil overheating

As mentioned above, the oil and coolant temperatures should remain within 15 degrees of each other. If the oil is consistently getting too hot then the 6.4 oil cooler may be too clogged to operate effectively.

Replacement Options

The OEM oil cooler runs around $350-500. However, if you replace with the OEM part you may be replacing it again in another 50,000 to 80,000 miles. They sometimes last longer, but it’s a risk you must be willing to accept. Otherwise, Mishimoto offers an oil cooler upgrade for a mere $150 that comes with a lifetime warranty. Considering how frequently these fail we recommend upgrading to an aftermarket oil cooler to prevent having to replace the factory one over and over again.

5) Fuel Dilution Problems

Active regeneration is the process that attempts to help keep the DPF clean. The Ford 6.4 diesel does this by injecting fuel during the exhaust stroke. This allows the fuel to exit the cylinder and flow downstream in the exhaust. This helps keep the DPF cleaner and burn off harmful emissions. However, there’s an inherent flaw to the way Ford designed this system.

Some engines use an extra injector to spray fuel directly into the exhaust stream. The 6.4 Powerstroke injects the fuel into the cylinders on the exhaust stroke. This allows small amounts of fuel to deposit on the cylinder walls where it can then contaminate the engine oil. Some fuel dilution of the oil is OK and shouldn’t cause any harm.

However, if too much fuel mixes with the oil that can affect the oils ability to properly cool and lubricate the engine. This could lead to premature wear and tear on the engines internals. This ultimately is really bad for engine longevity.

How to Avoid Fuel Dilution

There really aren’t any symptoms or specific fixes for the fuel dilution problems on the 6.4 Powerstroke. Instead, we’ll discuss a few ways to minimize fuel dilution and reduce the risk of it causing premature wear.

First, avoid excessive idle time as the cylinders cool down during idle. This increases the likelihood of fuel sticking to the cylinder walls and diluting the oil. It’s also a good idea to allow the engine to warm up before subjecting the engine to heavy loads.

Lastly, we recommend having an oil analysis done from time to time. It’s pretty cheap and will tell you just how much fuel is mixing into the oil. You can then adjust your oil change intervals to account for the fuel dilution.

6) Cracked Pistons

This is one of – if not – the least common engine problems on the list. However, it’s one of the more serious issues so cracked pistons are worth the quick mention. This is most common on higher mileage trucks, especially north of 200,000 miles. However, piston failures can and do occur on lower mileage engines. When it comes to adding performance mods to the 6.4 Powerstroke, adding additional generally increases the likelihood of piston failure significantly. If you are looking for big power gains you’ll want to look into upgraded pistons.

Ultimately, the pistons on this engine simply aren’t that durable. That’s not to say they’re terrible, and this problem may be blown out of proportion to some extent. Nonetheless, the “fuel bowl” in the piston is typically where the cracks first develop. They can then get much worse and lengthen across the entire piston. If it’s bad enough you can begin losing parts of the piston and causing catastrophic engine damage.

Piston Failure Symptoms

A few symptoms that may indicate piston issues include:

• Excessive smoke
• Loss of compression
• Power loss
• Misfires

Piston failures on the 6.4 Powerstroke can result in excessive white smoke from the exhaust. You may also notice a loss of compression if you perform a compression test. That can in turn lead to power loss and misfires if the cylinder isn’t building proper compression.

Piston Replacement

Since pistons are an internal part of the 6.4 diesel it’s not a cheap replacement. The engine will need to be opened up so it’s a very labor intensive job. There’s also somewhat of a conundrum on higher mileage 6.4’s. If you’re going to open up the engine to replace one faulty piston you’re likely looking to keep the truck for a while longer. At that point, it likely makes sense to replace all 6 pistons and some other parts while you’re in there.

Of course, that can add a lot of costs especially if you plan to upgrade a few things in the engine. It’s a good idea to do this stuff if you intend to keep the engine running for a long time. Otherwise, a cracked piston very well may not be worth the cost depending on current engine mileage and condition.

Ford 6.4 Powerstroke Reliability

How reliable is the Ford 6.4 Powerstroke turbodiesel? This is a tough one to discuss. Some swear by the engine and claim it was a massive improvement over the previous 6.0 Powerstroke. Others have had terrible experiences with the engine and dub it one of the least reliable Ford diesel engines. Reality likes falls somewhere in between the two.

The 6.4 Powerstroke isn’t alone here. It was made in an era where emissions equipment was becoming more and more complication. We skipped over a few of those problems in this post that may also be considered common. Nonetheless, a lot of failures like DPF, EGR, oil coolers, etc are due to emissions laws and additional equipment required. A lot of this can be deleted to make the engine more reliable. Though, the engine also suffers from a few unrelated issues like radiators, pistons cracking, HPFP wire chafing, etc.

That said, we’ll give the 6.4 Powerstroke average remarks for reliability. It’s certainly not as reliable as some of the older legends like the 7.3 Powerstroke or 5.9 Cummins. However, it’s a totally different ball game now days with all of the emissions stuff so it’s not a totally fair comparison.

Summary

Ford only used the 6.4 Powerstroke for two short years as they quickly introduced their own engine that was built in-house. Unfortunately, the 6.4 Powerstroke hasn’t earned the greatest reputation, either. Some consider it a great improvement over the 6.0 while others think 6.4 is just as bad. It’s a different era with all of the strict emissions requirements.

All that said, the 6.4 Powerstroke earns average remarks for reliability. Sure, it’s not on the same level as the 7.3 PS or 5.9 Cummins, but it’s a different era. Maintain your diesel well and upgrade stuff as problems pop up. It might cost a little money, but with the right upgrades you can significantly increase reliability and longevity.