It doesn’t matter how many diesel engine articles we make, there are always Ford guys in the comments swearing up and down that the 6.0L Powerstroke is a great engine and it’s Ford’s fault for cranking up the power, and it’d be fine if it made the intended 180hp and all this stuff. You guys remind me of all the Subaru people that swear the EJ is a reliable engine, and it’s just bad maintenance from bad owners that gives it a bad name. Meanwhile, they’re on their third motor in two years.
Anyways, I wanted to get to the bottom of this and find out if the 6.0L Powerstroke is really as bad as people claim it is, or are the Ford guys right? Is it actually a decent engine that was ruined by Ford’s demands for more power? And, can it actually be reliable with the right modifications in place to fix the design flaws found all over the engine. So, get your popcorn and get comfortable; we’re going to look at every issue on the 6.0L Powerstroke, how to fix the issues, common modifications to improve longevity, and a whole lot more.
Where Did it Come From?
Before we get deep into the 6.0L, I think we should quickly look at where it came from and why Ford ditched the 7.3L Powerstroke in favor of this engine. After the success of the 7.3L Powerstroke from 1994.5 to 2003, Ford was facing new emissions standards coming into play from the government that we’re going to be enforced in 2004.
Ordinarily, this wouldn’t be an issue. You could just make some adjustments to your emissions equipment or add new emissions equipment to meet stricter standards. The problem was the 7.3L Powerstroke had no emissions components on it, and it wasn’t designed to use emissions components at all. While they technically could’ve tried to adapt the 7.3L Powerstroke with modern emissions parts, namely an EGR system, there’s no guarantee that it would’ve worked well and still made the target horsepower level that Ford was looking for.
So, Ford and Navistar knew that it would be better to develop an all-new engine rather than trying to update the old dinosaur 7.3L Powerstroke engine, which is how the 6.0L came to be in Ford’s F-Series trucks. I do want to note, that the 6.0L Powerstroke is based on the Navistar International VT365 engine, which is arguably slightly better due to a handful of reasons that we won’t get into with this article.
Compared to the 7.3L Powerstroke, the 6.0L was a big jump in terms of performance and emissions. A few key features include the four-valve cylinder heads, a quick-spooling variable geometry turbocharger, a lower voltage and higher-pressure version of the HEUI injection system, and a crankcase bed plate for superb bottom-end strength. Funny enough, a lot of the “advancement” on the 6.0L Powerstroke are also the same things that cause issues.
In terms of power, the 6.0L Powerstroke produced 325hp and 560lb-ft to 570lb-ft of torque, which was a pretty massive upgrade from the 7.3L Powerstroke, which only produced 275hp and 525lb-ft of torque at its best. The VT365, on the other hand, is detuned quite a bit and produces 175hp to 250hp and 460lb-ft up to 620lb-ft, depending on the application.
I think it’s also quickly worth noting that the 6.0L was mentioned in Ward’s 10 Best Engines of 2003 for all of its advancements. Of course, it was a new engine at that time, and all the issues we’re about to get into were uncovered just yet. Keep that in mind next time somebody touts their favorite engine being a Ward’s Best Engine award winner. At the end of the day, that award doesn’t mean much of anything.
Okay, so getting into some of the issues of the 6.0L, let’s start with the added emissions systems since those are some of the main culprits in the 6.0’s long list of issues and bad designs. First up, let’s look at the EGR cooler.
#1 EGR Cooler
Now, as a quick refreshed, the EGR cooler has one job, and that’s to cool exhaust gases down before they enter back into the intake. Otherwise, you’d have blazing hot exhaust gases entering the engine, and that would cause a whole host of other issues on top of being really bad for performance.
In previous articles, I’ve mentioned that exhaust gas recirculation systems are implemented to burn fuel that wasn’t burned on the first engine cycle. While that’s still true, the main function is to actually lower combustion temperatures by basically diluting the air/fuel mixture with a small amount of exhaust gas. With this in mind, it’s easy to understand why an EGR cooler is needed because cooler exhaust gases will help lower combustion temperatures more than hot exhaust gasses would.
Unfortunately, the EGR coolers on the 6.0L Powerstroke aren’t particularly reliable. What’s even more frustrating is that a failing EGR cooler will give you similar symptoms as a blown head gasket, which is coolant in the exhaust. It’s not uncommon to see a failing EGR cooling misdiagnosed on the 6.0L as a blown head gasket, and vice versa. On top of that, it’s not an easy job to complete, with it generally taking 10 to 12 hours to replace the EGR coolers on this engine.
The EGR coolers typically experience failure in the form of cracking. You have to remember that this system is dealing with crazy hot exhaust gases and, over its life, will heat and cool hundreds or thousands of times. On top of that, exhaust soot can clog the EGR cooler with time. This is especially true on trucks that spend a lot of time idling. Once the EGR cooler starts to get plugged, it becomes much less effective and won’t cool the exhaust gases properly.
I want to quickly mention that a lot of the EGR cooler failures also stem from the 6.0L Powerstroke’s oil cooler issues, which we’ll get to later in the article. But, basically, the oil cooler can get plugged up, and that will coolant supply over to the EGR cooler, and then when the EGR cooler gets too hot from lack of coolant, it will internally rupture and crack, which then lets coolant into the exhaust.
#2 EGR Valve
Combined with the EGR cooler issues is the EGR valve. The EGR valve is responsible allowing the cooled exhaust gases to enter back into the intake. It works by using two valves that are connected with a shaft. Because exhaust soot likes to stick to everything and make everything dirty, it also coats the shaft and the valves of the EGR valve. This can cause the EGR valve to either stick open or closed, which will then throw a check engine light and make your truck run poorly.
While the 6.4L Powerstroke is a turd, and we’ve made a whole article on that, Ford did attempt to fix the EGR valve sticking issue by using a much stronger electric motor to force the EGR valve open and close with a lot more force so that it wouldn’t get stuck.
There are a few different ways to fix the EGR cooler and EGR valve issues. Cleaning it with your regular maintenance is definitely recommended, but really that only delays the inevitable issues. One of the more popular and not exactly legal solutions is to simply delete the EGR system entirely. There are also some aftermarket EGR coolers out there, but for the most part, it seems like deleting the system entirely is the best way to ensure that it doesn’t pop back up. Thanks to all the aftermarket kits out there, it’s relatively easy, although still a very time-consuming job.
#3 Oil Cooler
Okay, moving on from the EGR issues, let’s take a look at the next big problem. Just like Anakin Skywalker, the 6.0L Powerstroke does not like the sand people. More specifically, when the oil cooler gets plugged up from the sand, it causes the oil temperatures to jump up, which then causes a whole host of other issues, including lack of coolant flow to the EGR, as we mentioned before.
If your oil cooler gets clogged from sand and gunk in your coolant, it’ll negatively affect the injectors, high-pressure oil pump, turbo, engine bearings, and a whole lot more. The only thing that sucks is that with a handheld tuner to monitor oil temperatures, catching this issue before it’s too late is really difficult.
On top of the possibility of the oil cooler becoming clogged, they’re also known to crack, which then introduces allows coolant and oil to mix, which yet again causes even more issues and is easy to diagnose improperly. The preventative fix for this is to add a coolant filter, which basically filters out the sand and gunk before it reaches anything and causes damage, and then you can replace the filter occasionally with your regular maintenance.
#4 HPOP Failure
Unfortunately, the oiling issues don’t stop there. Remember earlier when we mentioned the 6.0L’s use of HEUI injectors? That means that high-pressure oil is needed for the injectors to function. More specifically, the 6.0L Powerstroke requires a minimum of 500 PSI of oil pressure to start the engine. Combine that with the fact that the high-pressure oil pump is problematic, and you can see why the next set of problems are so annoying.
The high-pressure oil pump gets its oil from the oil reserve within the block at the front of the lifter valley. The oil gets there from the low-pressure oil pump, which is responsible for simply moving oil around the engine as any normal low-pressure oil pump does.
The oil in the reserve in the valley of the block feeds the high-pressure oil pump at the rear of the valley, which the high-pressure pump is driven by a rear gear train. The job of the high-pressure oil pump is to provide pressurized oil for the fuel injectors. This outlet pressure is controlled by the injection pressure regulator, also known as IPR.
There are a few things that can cause the 6.0L’s high-pressure oil pump to fail. Most notably, debris in the oil can very easily destroy the pump, but the first place you should actually look is at the IPR, where there’s a small metal screen that can get clogged up.
There’s also the inlet strainer, which is a filter that is supposed to stop debris from getting to the high-pressure oil pump, but unfortunately, this filter uses a low-quality mesh screen that is known for tearing. Once it’s torn, it’s no longer filtering as it should, and then you can debris entering directly into the high-pressure oil pump, which can tear it apart and cause it to fail.
#5 LPOP failure
If you thought the high-pressure oil pump issues were bad enough, it’s made worse by the fact that the low-pressure oil pump also has issues, and since the low-pressure pump is responsible for feeding the high-pressure pump, you can see the chain of reaction from one poorly designed part to another. Really, the low-pressure oil pump isn’t that problematic, but it is known for walking outwards and running into the front cover.
#6 High Pressure Oil Issues
The oiling issues we just went over are made even worse by the fact that the 6.0L Powerstroke and the VT365 both have a ton of o-rings all over the engine, which can cause damage, but most notably cause the high-pressure oil pump not to function correctly and then your truck won’t run because the injectors aren’t working, all from an oil ring. The main culprit of the o-ring issues is on the standpipe.
The standpipes are the tubes that supply oil to the oil rails for the injectors. Oil flows from the high-pressure oil pump to the oil brand, then to the stand pup, into a check valve, then into the oil rail. In multiple spots, there’s a possibility for leakage, with the most common leak coming from the o-ring on the standpipe. When an o-ring on the standpipe leaks, you’ll end up with basically not enough high-pressure oil to function the injectors properly.
Basically, the same thing applies to the dummy plug, where oil leakage can stop the oil rail from having enough pressure to feed to the injectors.
#7 HEUI Injector Problems
That leads us directly to the next major issue on the 6.0L Powerstroke, which is the HEUI injectors. Since the injectors rely on high-pressure oil to function properly, issues occur when oil begins to break down and sludge up the injector spool valve.
When the spool valve gets sludged up, the injector doesn’t work properly. More specifically, you’ll experience significantly worse fuel atomization and irregular injection events. If the issue is left for too long, it can permanently kill the injectors.
The fix for this comes in the form of oil additives that help to slow down or prevent the oil breakdown from occurring. Replace your oil often as you’re supposed to and use the right additives to prevent oil breakdown from sludging up the spool valves in the injectors.
Moving on from the oiling issues, let’s take a look at the fuel injection control module, also known as the FICM. This little box is what controls the injection events of the injectors, which need to be extremely precisely timed in order for the engine to run correctly. Functionally, the FICM is very similar to the IDM you’ll find on the 7.3L Powerstroke. To put that more simply, the FICM sends electrical pulses to the injector coil, which allows the spool valve to open and high-pressure oil to activate the fuel side of the HEUI injector.
There are a couple of things that cause issues with the FICM, most notably inadequate voltage for it to function correctly. If the voltage drops down, the injector coils will operate in a delayed fashion, and this can also cause the spool valve not to function correctly. The culprit of the lack of voltage is either dying batteries or dying alternators.
Leave it up to Ford to find a way to make a dying battery cause your fuel injectors to fail.
To make matters even worse, dying batteries can permanently damage the circuits in the FICM. Luckily, it’s not too hard to access the FICM since it’s right on top of the motor over the driver’s side valve cover.
Speaking of which, a lot of people online report experiences of their FICM overheating and their trucks refusing to start until the engine bay cools down. It’s almost like putting the FICM on top of the engine and right next to a blazing hot turbocharger was a bad idea.
#9 VGT Problems
Remember that new fancy variable geometry turbo that Ford added to the 6.0L Powerstroke? Well, unfortunately, it’s another source of problems for the 6.0L. When it’s functioning properly, the Garrett GT3782VA on the 6.0L is actually a pretty decent turbo, but getting it to function perfectly can be a challenge, especially as the miles rack up on your truck.
On the compressor side, this turbo is functionally identical to a standard fixed geometry turbo, but on the exhaust side, things get quite a bit different. The VGT works by using turbine vanes that are movable. When the vanes move, exhaust flow across the turbine wheel changes. If I put that more simply, this basically allows the turbo to act as a small turbo at low RPM for improved response and a bigger turbo at higher RPM for more top-end power.
The issue with the VGT is that soot and carbon can build up on the unison ring, which can cause it to stick or even seize up entirely. If the unison ring gets stuck, you’re either stuck with a really big turbo or a really small turbo, depending on where it is stuck in its range of motion. This issue is more common on trucks with a lot of idle time, where the unison isn’t active and can easily get stuck in place.
Aside from the unison ring, there’s also the possibility of the exhaust backpressure sensor getting clogged with soot. When this sensor or the line gets clogged up, it’ll give the truck’s PCM incorrect readings, and that will force the turbine vanes to act improperly.
#10 TTY Head Bolts and Head Gaskets
Of course, this wouldn’t be a 6.0L Powerstroke article if we didn’t talk about the most known issue of all with these engines, which is the head bolts and the head gaskets.
There are a few things wrong here: most notably is the use torque-to-yield head bolts, which aren’t new or special for modern engines. The issue with this style of head bolt is that it has a limited range of force that it can deal with. If you go past that yield range, the maximum clamping force of the bolts drops.
The other issue is that the 6.0L Powerstroke only uses four bolts per cylinder, meaning the entire load is spread across four 14mm bolts, which are bigger than the 12mm bolts found on the 7.3L, but the big difference there is that the 7.3L uses six bolts per cylinder. As to why exactly they thought four bolts per cylinder would be enough, I’m not entirely sure, and for reference, the Duramax and 5.9 Cummins engines from the same time period use six bolts per cylinder as well.
So, we’re talking about bolts that lose their maximum clamping force when stretched too hard and only four of them per cylinder. What happens is under heavy load and boost pressure, the heads can lift off the block and blow a head gasket.
With the head lifting, combustion can leak into the coolant system, and as a result, the cooling system quickly becomes pressurized and causes more issues. To be fair, though, the VT365, with its lower power rating, doesn’t suffer from head bolt stretching or head gasket failure really at all. And, in totally stock form, the 6.0L Powerstroke also rarely ever sees this issue. Really, it doesn’t become much of an issue at all until you start to turn the power up on the 6.0L.
Luckily, this issue is well known, and it’s not a complicated thing to solve. Simply swap out the torque to yield head bolts with aftermarket head studs. Not only will this get rid of the stretching issue, but aftermarket head studs will also provide significantly more clamping for, which means you can crank the power way up without the heads lifting off the block.
The last few things I want to mention on the heads are that they’re prone to cracking inside the injector bores of the heads. The cracks might be really tiny, but they can cause some really big issues. It’s also worth noting the rocker arms are well known for failing.
While Ford guys are right to say that the 6.0L’s issues are made worse when you crank the power up, they’re wrong to call the detuned VT365 found in industrial applications a “reliable” engine. Those detuned 6.0L Powerstroke engines still suffer from the same EGR issues, coolant flow issues, high-pressure oil pump issues, and more.
Of course, you have all the old geezers that are saying to leave your truck stock, and if they aren’t race trucks, and if you want to go fast, buy a car and blah blah blah. Listen, old man, we all like going fast, even if that means cranking up the power on an unreliable engine and making it even more unreliable.
Really, the original intention for the 6.0L Powerstroke was like 180hp, but Ford obviously needed that to be much higher in order for them to compete with what Ford and Dodge were hiring. The VT365 is an industrial engine that was pretty much just cranked up and plopped into the Superduty as the 6.0L Powerstroke.