Well, you’ve come to the right spot! Recently, we had a chance to exchange emails with C.J. Snyder, a diesel engine mechanic that’s an expert on the Ford 6.0 liter diesel engines. He’s agreed to let us share some of the incredible expert knowledge he shared with us on why the fuel injection system can be so picky (especially with Biodiesel) and what you can do about it to keep issues to a minimum. He’s preparing to run his own 6.0 liter Ford on Biodiesel. Check out all the great things he’s doing to get the truck ready! He goes into great detail about why he’s making the changes and what the issues with the injectors are
Prepping Ford 6.0 Liter Diesel Injection System for Biodiesel
Regarding the issues with bio[diesel] and the fuel injectors in a 6.0, I will be using a centrifuge on the processed biodiesel to filter it down to a very fine level (from what I understand, I can expect 1-2 microns), as far as making sure the injectors are fed the correct amount of fuel pressure, I will be installing a regulated return fuel system on the truck (along with head studs and many other upgrades to “bulletproof” the truck).
How The Injection System Works
The stock fuel system regulates fuel pressure at the fuel filter bowl on top of the engine, before the injectors. It then goes through a pair of small steel hard lines, through small banjo bolts to the front of the heads. It then goes through a channel machined in the heads that the injectors bisect, so the fuel fills up the first injector, then the next and so on in series. At the back of the head, there is a block-off plug that closes off the channel that the fuel is in. This is called a “dead-head” system.
Upgrading The Setup
The regulated return fuel system eliminates the factory regulator and replaces it with a block-off plate, the fuel goes through a set of larger hard steel lines through much larger banjo bolts to the front of the heads, where it fills up the injectors in series like before. The big difference is that the regulated return system removes the block-off plugs at the back of the heads, and instead plumbs in banjo bolts and a set of hard steel lines that come out of the back of the heads, they then feed into an adjustable pressure regulator, which regulates the fuel pressure after the injectors, ensuring the injectors get full fuel flow at all times. The regulator then dumps any unused fuel into the stock return line, then sends it back to the tank. At the regulator, there is a port where I will be inserting a pressure sensor, so I can use my EDGE Insight CTS monitor on the inside of my cab to see the fuel pressure. The big issue that people have with the 6.0 injectors (besides self destructing duel to lack of fuel flow) is the lack of lubricity in the ULSD we get at the pump. All the moving parts in a 6.0 injector need lubrication to keep them happy, and ULSD doesn’t have enough. Biodiesel is pretty much the best you can get as far as lubricity is concerned, so they should like it just fine.
We asked C.J. if the rear injectors on Fords typically were the first to go. Check out what he said (and how to prevent it from happening).
Yes, the injectors at the back of the engine (typically cylinders. 7 and 8) tend to take a crap first for 2 reasons. One is the lack of lubricity from the ULSD, which is sort of the fuel equivalent of Coors Light (beer flavored water), in fact that is the single biggest issue.
However, there is a second reason that a lot of people don’t realize, and that is the fuel also acts as a coolant. Remember, the nozzle of the injector is sticking out in the combustion chamber, which gets up to about a million degrees, and all of the heat that gets absorbed by the nozzle gets transferred to the rest of the lower parts of the injector.
Couple that to the fact that the up-pipes that lead from the exhaust manifolds to the turbo run up the back of the engine, the HPOP (High Pressure Oil Pump) sits in the back of the engine and the turbo sits in the back of the valley of the engine, and it gets to be like a pressure cooker for the rear cylinders. If there isn’t enough fuel getting to the rear injectors (like if fuel pressure was too low), then the fuel can’t absorb the heat out of the injectors and transfer it to the cylinders during combustion, and the injectors get very hot and, in some cases, the metal reaches it’s fatigue point. I’ve actually seen the tips of injectors melted off, they fell into the cylinders and were forcibly introduced to the tops of the pistons, and everyone had a bad day (except the mechanic that got to put in a long block, like me!) The other thing that causes that is water in the fuel. It can actually cause a small steam explosion in the tip of the injector and blow the tip off!
Another thing you can do to alleviate heat build up in the rear cylinders is to install a coolant circulation line kit. You drill into the coolant jackets in the back of the cylinder heads, and plumb in a set of braided stainless lines that go to the thermostat housing, so the coolant at the back of the heads doesn’t have to go through the rest of the engine and absorb even more heat before it goes to the radiator.
He also had another side note about the fuel pressure issue too…
As a side note regarding fuel pressure in the 6.0, Ford knew about the injectors sensitivity to low pressure. To try and alleviate that problem, they released what is called the “blue spring upgrade”. The stock regulator is nothing more than a spring loaded poppet valve. When fuel pressure exceeds about 55 psi (like at idle, assuming everything is working properly”, the pressure pushes the valve open against the spring pressure, and dumps the excess fuel to the tank.
Unfortunately, keeping fuel pressure at that level at idle, coupled with the fact that the spring fatigues over time and weakens, and it can affect throttle response off-idle and power output at WOT.
So, Ford came out with the “blue spring upgrade” which is nothing more than a stronger spring that is also about a half inch longer. This bumps fuel pressure up to about 65 psi at idle, and helps to hold more pressure at WOT. There are kits that allow you to mount a pressure gauge in the cap of the secondary fuel filter, but that means you have to either pop the hood to check pressure (at idle only please!) or mount an aftermarket gauge somewhere on the inside of the truck.
As long as fuel pressure doesn’t drop below 45 psi, you’re good to go. The step up from the “blue spring upgrade” is the regulated return fuel system. I would recommend doing it to any one who wants their injectors to last (regardless of fuel type), and I would consider it a mandatory upgrade on trucks running an aftermarket tune, bigger injectors, or both.
One more thing regarding the 6.0 injection system;
I have spoken at length about the fuel side of the injection system and how you need to be careful with fuel quality and pressure and various modifications you can do to keep that system happy, but there is a whole other side to the injection system that demands just as much, if not more attention and diligence, and that is the oil side.
The 6.0 (and 7.3) use what is called a HEUI injection system. HEUI stands for Hydraulically-actuated Electronically-controlled Unit Injector. That basically means the injector is fired using high pressure engine oil, but controlled electronically by the FICM (Fuel Injection Control Module (on the 7.3 it is called the Injector Driver Module, or IDM)). The best way to think of the construction of a 6.0 injector is like a hypodermic syringe. The needle of the syringe is the nozzle of the injector. The chamber that holds whatever it is you are injecting on the syringe is the fuel barrel of the injector. The seal between the plunger and the chamber of the syringe is the “intensifier piston” (more on that in a bit) in the injector. Your hand pushing on the plunger of the syringe is the high pressure oil in the oil barrel of the injector. The oil system is as follows; some engine oil, after it goes through the oil cooler, gets sent to the HPOP (High Pressure Oil Pump). It gets pressurized to a certain psi, up to 4500 if the PCM calls for it, it then goes through the Snap-To-Connect (STC) fitting (one of the real problem children on a 6.0, can cause hot-start problems if it fails).
From the STC fitting, it goes through 2 branch tubes that sit in the bottom of the engine valley in the back of the block. They then lead into the stand pipes, which go up through the heads and carry the engine oil to the high pressure oil rail. The oil rail is what supplies the oil to the injectors.
The whole high pressure oil system has many points of failure that can lead to hot-start and no-start problems, and it will take me an eternity to run though them all, so I will just focus on the injectors themselves. The first thing the oil encounters in the top of the injector is the spool valve. This is the valve that controls the flow of oil into the injector. The spool valve is just a small bar of steel that has a hole drilled in it off-center that sits in a chamber that allows it to slide back and forth. On either side of the chamber are 2 electro-magnetic coils, one is for “open”, one is for “close”.
When it is time to open the injector, the FICM sends 48 volts of electricity through the wiring harness to the “open” coil. This creates an EM field around the coil and drags the spool valve over to one side. When it does this, the off-center hole in the valve lines up with the opening in the top of the injector and allows the pressurized oil into the oil barrel of the injector. The oil barrel of the injector is sealed off from the rest of the injector by the intensifier piston (remember him from earlier?), but the piston is able to slide up and down, it is held in the “up” position by a spring.
The oil is under such pressure that it overcomes that spring tension and pushes the piston down. Now remember, the fuel barrel under the piston is already filled with fuel, so when the piston starts to come down, the fuel pressure skyrockets from between 45-70 psi to over 20,000 psi (because you can’t compress a liquid, so pressure climbs much more than with a vapor), and it starts looking for a way out.
The fuel inlet through the side of the injector has been sealed off by a reed valve (I think?), so the only way out is through the nozzle, which is sealed with the pintle. But, the pintle has a spring at the top of it, so the now-pressurized fuel forces the pintle up against the spring and injects itself into the cylinder.
Once all the fuel is injected, there is no longer any pressure holding the pintle up, so it comes back down and re-seals the nozzle. At the same time, the FICM has stopped sending voltage to the “open” coil, and has instead sent it to the “close” coil, which drags the spool valve to the other side of the chamber, closing off the oil barrel from the rest of the oil system, the spring on the intensifier piston pushes it back up, dumping the oil back into the crankcase, thus ending the injection event. (Whew, sorry there is no short-hand for explaining this process)
Because the injector relies on engine oil to fire it, and that spool valve has very tight tolerances in it, you would assume that clean oil is a must, and you would be correct. Most of the 6.0 injector failures you hear about are due to spool valve failure caused by varnish building up on the inside of the chamber that the spool valve sits in. It will cause a very noticeable misfire, and has even earned a name from 6.0 enthusiasts, called “stiction”, a combination of “sticking” and “friction”. To stop this problem from happening, there a few things you can do.
1- Use a good quality semi-synthetic or full synthetic oil (I use Shell Rotella T6 5w40 because at about $23 for a 5qt. jug, it’s cheap and my local Wal-Mart has it.)
2- Change your oil at least every 5K miles, if you are using it hard, go closer to 3K, you cannot stretch out the intervals like a 7.3
3- If you really want your oil to stay clean, do what I did and get a “bypass oil filtration” kit, I recommend the combo coolant filter and oil filter kit from MKM Customs (Sinister Diesel). After all of your oil goes through your factory “full flow” filter, about 20% gets drawn off through a new filter cap they send you, through a braided S.S. line to a second filter. The one I use as a Amsoil EaBP 100 filter which takes it down to a much finer micron level. It then goes through another brained S.S. line to an new oil fill cap they supply, where it is returned to the crankcase. With regular Blackstone Labs testing, this has been known to double or even triple oil change intervals!
Ford themselves know about spool valve problems, especially in cold weather, so they have a strategy in the FICM called an “Inductive Heating” strategy. On a cold morning, when you turn the ignition to the “on” position to wait for the glow plugs to heat up, you will also hear a very loud and fast paced clicking noise from the engine. That is the FICM cycling all of the spool valves in the injectors at one time (which is what burns up FICM’s, but that’s another discussion) to try and overcome stiction. If you already have a misfire that you think might be caused by stiction, you can add an additive called Rev-X to your oil. Do not add it to your crankcase through the fill tube though, remove your oil filter and the standpipe for the filter and pour it into the hole under where the fill tube would be, that leads straight to the HPOP, so you can make sure that the injectors see the Rev-X ASAP. Be warned though, Rev-X really isn’t a permanent fix, after guys have used it to get rid of stiction and they changed their oil, the stiction-misfire sometimes came back.
Issues with the 6.4 Liter Ford Engines & Biodiesel (2008-2010)
One more thing regarding finicky fords. If you hear about anyone trying to run biodiesel concentrations higher than the recommended b5 in a 6.4 (2008-2010), especially in one with a steel tank like an f350 and up with a utility body or dump bed on it, tell them to knock that [#$%^] off immediately.
Besides the issue with the DPF that you are already aware of, the trucks with the steel tanks have been experiencing an issue that has been dubbed “delamination”.
The steel tanks are actually 2 layers, an inner and an outer layer. The inner layer, even with ULSD, starts rusting, and flakes of it fall off and get sucked up by the fuel pickup. They then make their way to the DFCM (on a 6.0, it is known as the HFCM, basically the same thing, a pump, primary filter (10 micron), heater, and water separator).
Because these are nice sharp pieces of rust, they shred their way through the filter and go to the secondary filter on top of the engine (3 or 5 micron, can’t remember exactly), shred that, then go through the fuel cooler (looks like an oil cooler, has a little tiny coolant reservoir on top of it, sits behind the filter bowl), goes into the HPFP (High Pressure Fuel Pump), trashes that, then to the injectors where they create unholy amounts of carnage.
All of this awesomeness leads to a full fuel system replacement which requires removal of the cab to accomplish (care to guess the labor cost of that?)
Here’s the best part. Standard fuel filter change intervals on a 6.4 are every other oil change, or 10K miles.
The “EXTREME SERVICE” interval backs that down to every 5K miles. What most owners of these trucks don’t realize is that about 95% of these trucks fall into the “EXTREME SERVICE” standards.
At the dealership I worked at, I personally witnessed several of these trucks come in for this service. They had been lifelong customers and followed the service intervals to the letter, except the fuel filter changes because Ford didn’t tell them and they didn’t know better.
We would disconnect one of the lines into the fuel cooler, and take a very small extendable magnet and stick it down in the cooler. If we brought up pieces of rusted steel with the magnet, we would pull the service records, discover they hadn’t been changing the filters enough, and FORD WOULD REJECT THEIR WARRANTY CLAIM! In other words, they would be about $6,000 out of pocket for the repair.
Parts cost, about $3000
Labor, around 30 hours at about $120/hr, about $3500
Sticking the customer with the cost because they did what they were told, priceless.
Given the crud eating nature of biodiesel, I can only imagine how much worse this situation would be made by using more than b5, just something I wanted to make you aware of.
Talk about awesome knowledge!!! He’s agreed to field any of your questions down in the comments section too, so shoot away!
Also, as an aside, if you’d like to learn more about the 6.0 liter diesel engine, be sure to check out this awesome video series on YouTube by a diesel engine mechanic that works on nothing but Ford diesel engines!