By Bob McDonald
Diesel engine specialist
If there is one engine that plagues the mid-size diesel world, you would have to say that it is the 6.0L Power Stroke.
This engine has the worst repair history that has plagued and continues to plague Ford truck owners today. Even though the engine was only produced from 2003 to 2008, truck buyers often steer away from these engines when purchasing a diesel truck.
One comment often heard is, “Why did International stop producing the 7.3L engine?”
Well, there are some areas that need to be covered as to why the 6.0L came into existence and some remedies for the problems that have absolutely ruined the Ford truck reputation for these model years.
The 6.0L came into existence because the EPA demanded tighter emissions laws for diesel engines. Even though the 7.3L was branded as the reliable workhorse for Ford, it would never be able to pass the tighter emissions laws that were going to come into effect for 2004.
In saying that, I often feel that owners of 7.3L Power Stroke engines don’t realize that their engine was designed to meet emissions also.
That was why the HEUI design of the 7.3L was released in 1994.
Tougher emission laws were coming into effect in the mid ’90s, so they were ahead of the game as far as meeting emission standards and having a very dependable engine with the 7.3L.
This was one of the reasons that these engines were fitted with a catalytic converter.
To meet the emission standards of 2004, the EPA would require diesel engines to be cleaner. These standards meant that fewer nitrogen-oxide levels of diesel exhaust could be released into the air.
For International, this was the start of the snowball that would slowly start its descent down the long hill.
The only way to cut down on emissions was to utilize an EGR (Exhaust Gas Recirculation) valve and come up with a more efficient engine. In saying that, you have to realize that the 7.3L was a good engine, but it was not very efficient.
As soon as you install an EGR valve on a diesel engine, power drops pretty quickly. If you are wondering why, let me explain.
When incorporating an EGR valve on a diesel engine, the object is to bring exhaust gas back into the intake manifold to be re-burned.
When the exhaust gas enters the intake manifold, you have displaced the oxygen that was being brought in from the outside air for combustion.
So then, combustion temperature drops because there was not a complete burn. This in turn makes soot, which starts clogging up everything.
But, before you can introduce exhaust gas into the intake manifold on a diesel engine, you have to cool it.
Under a load, diesel exhaust gas temperatures can get as high as 1,000° F or more. So, exhaust gas travels through what is known as an EGR cooler.
This is a cooler that is circulated with coolant from the engine, and is mounted under the intake manifold.
Exhaust gas travels out of the manifold through an opening in the pipe, which then enters the cooler before exiting into the intake manifold.
One of the problems that the 6.0L had was that the EGR cooler would not “live” too long. Over a period of time, the coolers would bust from the exposure to the extreme heat.
When this happened, antifreeze would seep out into the exhaust system causing steam. A lot of times, owners would often notice this when they pulled up to a stoplight.
Clouds of steam would pass by them while they were waiting for the light to change.
Owners would often notice a puddle of antifreeze under the vehicle after being parked for several hours. Sometimes they would ignore the EGR cooler leak and continue to drive the vehicle until one day the engine wouldn’t turn over.
What would happen was the cooler would leak into the exhaust system overnight.
The leak would be so bad that the exhaust manifolds would fill up with coolant, which would run into a cylinder with an exhaust valve open.
This would cause the engine to hydro-lock, which could bend a connecting rod when trying to start the engine.
Powering Up the Power Stroke
There was a lot at stake for International. Not only did they build a smaller engine that is more efficient and able to carry an EGR valve, but it also had to make power.
Customers wouldn’t want an engine with less power. So, the 6.0L was a great accomplishment versus the 7.3L. It is still an HEUI design, but now has four valves per cylinder.
The combustion chambers in the pistons have been redesigned along with the addition of a VGT (Variable Geometric Turbo).
When making a smaller package, you tend to lose room for fasteners. By redesigning the HEUI engine, the cylinder heads went from six head bolts per cylinder to four.
Which should not be a problem, but the engine was faced with a lot of boost, especially if you install a programmer.
The VGT was designed to utilize boost throughout the rpm range.
If you remember, the 7.3L made great torque down low and wouldn’t make boost until the engine was up in the rpm range. With the small 6.0L, in order to make power down low, you had to make more boost to propel the engine.
This would prove to be a problem with four head bolts per cylinder.
The bolts in question are called torque-to-yield, meaning that when they are torqued down properly, they stretch to the correct limit and clamp the gasket.
But, what happens when you force a high level of boost into the engine, stretching the bolts more?
You end up with an over-stretched bolt that unclamps the head gasket and causes a leak.
So, one of the many problems was leaking head gaskets. Just because you may have had them replaced once didn’t mean that you wouldn’t have to replace them again.
Having the turbo as a variable geometric style meant problems as well.
The turbo was a great addition by Garrett, but having soot in the exhaust system from the EGR valve meant that the “vanes” would stick.
The vanes of the VGT are on the exhaust side of the turbo and are controlled by an actuator that is fed with oil pressure from the engine, which is used to cool the turbo.
The actuator is controlled by the PCM and will move the vanes, which are mounted to a rotating plate with oil pressure.
The vanes actually change the way the exhaust gas enters the turbo and spins the exducer wheel.
So the turbo speed is controlled by the PCM based on input from the other sensors of the engine.
This is a great way to make power throughout the entire rpm range until the vanes stick due to soot buildup.
With a smaller engine package you have to start coming up with inventive ways to place things on the engine. A great example would be the oil cooler.
If you remember the 7.3L, the oil cooler was mounted externally on the driver’s side of the engine, just below the deck of the cylinder block.
If there were anyproblems, the oil cooler could be accessed fairly easily for repair.
But on the 6.0L, the oil cooler is mounted inside the top of the engine under the oil filter.
There aren’t really any issues with leakage as much as the cooler itself becoming clogged.
Because of the design of the cooler, over a period of time, the passages become clogged, causing a rise in oil temperature.
Because oil is used to lubricate the turbo and operate the injectors, along with cooling the pistons, this becomes a major problem.
These are the most common failures of the 6.0L engine.
But because of updates and the help of the aftermarket, a lot of the 6.0L issues can be solved to make this engine very reliable.
We’ll start with the EGR cooler. There are two ways to approach this.
One would be to delete the cooler and delete the EGR valve. Of course in doing this, the engine would no longer be emissions compliant.
This really doesn’t seem to matter too much to a lot of owners unless the state they live in has tough emission laws.
One kit that I have found to have great success with is the EGR delete from Gillett Diesel (www.gillettdiesel.com) from Bluffdale, UT. The delete kit comes with all the necessary gaskets and hardware to delete the EGR cooler.
Another solution to the problem is to install a better cooler made to handle the job. This would be from Bullet Proof Diesel (www.bulletproofdiesel.com) from Mesa, AZ.
Their EGR cooler has a totally redesigned cooler core made entirely from stainless steel, which will not fail from normal stress like the OEM style.
Either choice of repair will take around four to five hours of labor.
One thing that I will say is, either way you choose, if the vehicle has some miles on it, take the time to replace the oil cooler.
While you’re removing the intake to perform this repair, it would be wise to go ahead and replace the oil cooler while you will be looking right at it.
This is where you would have to make another decision.
The OEM cooler is going to cost around $350 from the dealer. You can replace the cooler with this part, but remember, you may be faced with this repair again.
My suggestion is to ask the customer if they plan keep the vehicle for many more years. If they do, you may want to recommend to them a better cooler like the one also offered from Bullet Proof Diesel.
Their design moves the oil cooler to the front of the vehicle. The oil cooler will no longer be mounted inside the engine.
So, if problems would arise in the future, the repair would be a lot simpler to address. The only drawback is the price.
This style of cooler does cost more than OEM, but the design and integrity is way far superior.
Something else that I always encourage is to clean the turbo, especially if you’re going to delete or replace the EGR cooler.
The turbo has to come off of the engine in order to remove the intake to access the EGR cooler. So why not take the time to clean the turbo? This isn’t a hard job, but you’ll need to pay attention to how the turbo comes apart.
Loosen the large clamp around the exhaust housing of the turbo. Next, pry the exhaust housing away from the body of the turbo. Lay the turbo on a bench with the intake side facing up.
When prying the exhaust housing away from the turbo, the vanes will remain in place on the exducer side so you can see how they are oriented in the turbo. Take the time to clean the vanes along with the rotating plate.
A lot of times you’ll notice that not only does the turbo contain soot, but also rust and scale that will cause the vanes to stick. Once this cleaning is performed doesn’t mean that it won’t happen again. But, it may give you a better understanding of how the turbo functions.
The last thing to talk about would be the head gaskets. This repair is going to come sooner or later. My suggestion is to fix this the first time. There are two different repairs that I’ve found that will cure the problem.
If you purchase OEM-style gaskets, they will work just fine. The gasket material is MLS (Multi-Layer Steel), which has been used by automakers for several years now.
The only reason I see gaskets fail are due to the bolts that stretch. So you can use the OEM head gaskets, but I suggest the use of head studs.
The choice of head studs would be from ARP (Automotive Racing Products), which has been manufacturing quality fasteners for the racing industry for years.
The studs are formed from a material like hardened chrome-moly, which has a tensile strength of 190,000 psi. Once installed correctly, these studs will never stretch, which should never cause any fatigue on the gasket.
The only problem with running MLS head gaskets is the deck surface and head surface must be absolutely smooth. This is referred to as the RA (Roughness Average). If there are imperfections in the surface of the block or head, it will need to be machined in order to obtain the proper seal.
When MLS head gaskets are torqued, they often leave imperfections in the deck of the block and head because the steel gasket is embedding itself into the surface. If you are faced with this situation, there is another option for repair.
There is a 6.0L head gasket made by Hypermax for these imperfections. The gasket is made of a graphite material just like the ones used on the 7.3L engines.
In addition, the cylinders are insulated with stainless steel “fire” rings, which completely seal the cylinders. These gaskets live under the toughest conditions and will not blow unless you add more than one programmer to your vehicle.
Most head gaskets on the 6.0L engine tend to fail quicker when a programmer is installed. Most aftermarket companies try to keep their programmers at around 65 hp for this engine.
Some companies will offer more, but you play at your own risk. Adding more power tends to accelerate the stretching of the head bolts.
By installing a head gasket from Hypermax, most programmers can be installed without any detrimental effects. Hypermax even guarantees them to 650 rear wheel horsepower. If your engine makes more than 650 hp at the rear wheel, you’d have to be installing more than one programmer. They tend to call this “stacking” chips.