Injector Cup Failure in Powerstroke

Injector cups are a very vital part of the internal workings of a Powerstroke diesel engine, whether it is a 6.0L or a 7.3L.  The injector cup seals the cooling system from the injector inside the cylinder head.  When the injector cup fails, you will no longer have a seal between the fuel system and the coolant system.  Because of the higher pressure of the fuel system, the fuel goes into the coolant. This video addresses how to identify the problem, how to diagnose the problem and how to repair the problem.

Indentifying the Problem

The number one indicator of a problem with an injector cup is fuel in your coolant.  Usually, fuel will overtake the cooling system and push past the cap.  It is important to identify fuel in the cooling system early because the longer it stays in there, the more damage it does to all the rubber components of the cooling system. This bottle is cracked and broken down from the petroleum reacting with the plastic.  During your under-hood inspection, if you see your coolant bottle is overfilled or overflowing in any way, pop the coolant cap off and inspect it.  Often, when you remove the cap from the truck, this seal will be deformed and expanded from reacting with the petroleum. This particular truck came in with the coolant cap replaced because the rubber seal was all deformed from reacting with the petroleum.

Diagnosing the Problem

Once you identify that you have a problem in your cooling system and there is fuel in the coolant, then it is time to do some investigation.  This diagnostic procedure is fairly involved and requires a pump to pressurize the cooling system.  You are going to have to take the injectors out which requires removal of the valve covers, the valve cover gaskets, and all of your fuel injectors. While you have the injectors removed, now is a good time to replace the seals and check your glow plugs to make sure that they are all in working order.  It will be easy enough to replace them all now while you have it apart.

With the valve covers are off and injectors removed, it is easy to see down into the injector cups with relative ease.  Some on the passenger side by the air conditioning box can be a little challenging but they can be done.  It is really important that you take some brake cleaner and good clean towels (not fuzzy towels that will leave fuzz inside this system, good clean shop towels that have been used a bit and are washed and nice, dry and clean) and clean the individual cups.

Use the pump, pressurize the cooling system, and watch the injector cups very closely in each of the 8 cylinder holes to find which one has the leak.  With each hole clean and dry, it should be relatively easy to see the coolant emerge.  With the system pumped up, you can see the coolant form and push down into the cup.  You have to be very patient and keep the system pressurized.  It is helpful to have a friend pump the system while you are observing each individual cup.  The only way you are ever going to see this leak is if the cup is extremely clean and dry.  If you look very careful and take your time, you will find the injector cup that is leaking, or two or three.  In this particular situation, we have identified that the number 2 cylinder which happens to be an easy cylinder is the one that is actually leaking.  More often than not, we recommend that you replace all eight, but this particular customer does not have the time or inclination and does not want a warranty so we are just going to replace the one cup.

Parts and Tools

Now that you know which cup(s) you are dealing with, order the injector cup(s). If you do not have a Ford dealer that has one in stock, sometimes you can get them from International, but you’ll have to twist their arm to look it up for you because they don’t like to sell parts for Fords.  You will also need the removal tool and the installation/driver tool.  With the removal tool, you thread it down into the cup.  There is a puller that grabs the top of the hole and extracts the cup from the hole.  The installation/driver tool is simple and straight forward – Stone Age technology.  You put it down in the cup and drive it in carefully with a hammer.

Repairing the Problem

Depressurize the system and remove the pump.  Then crawl under the truck and drain the coolant because once you get the cup loose, the coolant is going to drop right down into the combustion chamber which we don’t want to have happen.  Once you have the coolant out of the system, now is the time to thread in the extraction tool.  We are going to remove the exhaust side rocker arm and the front rocker arm so we have visual access.  It is not really necessary for the extraction process, but when you start working on some of the rear cylinders, it might be a good idea to get these rocker arms out of the way for ease of accessibility.

I am a real stickler about the parts coming off and going back in exactly the same spot.  Order of parts and how they went in is crucial as far as I am concerned.  If an engine has 100,000 miles on it, and that tip of that rocker arm has been working on the tip of that particular push rod for all these miles, then why am I going to go and mix it up with something else?  The wear patterns have established themselves and it just seems to be a good idea to make sure that each part goes back together exactly as it came out.

So this upper nut (12 point, ½ inch or 13 mm head) actually drives the tool down into the cup.  Right now, we are actually threading the tool down into the cup.  It will take 8 or 9 turns.  You don’t want to push it when you get it to the bottom.  Don’t stress it.  When it is bottomed, it is bottomed.  Once the tool is driven into the injector cup, the outer nut is tightened down against the retaining ring and this is how it gets pulled out.  You have to use a deep ¾ inch socket, 19 mm.  Out she comes.  It gives very easily.  Having the right tools goes a long way towards having a happy outcome.

Now that the injector cup is loose, it is just a matter of pulling the whole shebang right out.  Just like playing operation when you were a kid.  Now that we have it apart, it is apparent that the injector cup has a long crack in it, probably caused by heat and materials, heating up and cooling down.  It will cause a stress fracture in the injector cup.  Now, get the hole that the injector cup goes into clean, clean, clean, clean.  You can’t get it too clean and dry before we install the injector cup.  There will be some residual glue in the hole.  It is absolutely imperative for all of that stuff to get cleaned out of there using whatever tools are necessary to do so.  It will take more than just wiping around in there with some damp rag to get this clean.  The cup has to seal against a clean, dry surface in order for this to be a successful repair.  A little wire brush like you use for cleaning solder off of cooper pipes works really good to reach down in there and clean that hole out.  You might get a little debris inside the cooling system, but we are going to have to flush all this nasty mess out of there anyway.  Now you are going to have to clean and clean and clean, brake cleaner, towels, whatever it takes to get that space clean.  I cannot over stress this.  Once you get it all nice and cleaned out, put some air down in there and blow all the residual pieces out.  Watch your eyes.  Don’t let it blow back into your eyes.  If that brake cleaner gets in your eyes, it will sting like a son of a gun.

We are going to use Permatex Threadlocker Green to seal this cup.  Slide the cup onto the installation tool.  You will notice a rubber o-ring on the installation tool.  It is crucial that the o-ring is there, because that is what holds the cup on there when you turn it upside down.  You will be pointing downhill with this and you need the o-ring to hold it on there.  Make sure the cup itself is dry and clean using brake cleaner so that our sealer will actually seal like it is suppose to.  Take a little bit of seal using a paint brush or swab and put it on the surfaces inside the head where the cup makes contact.  The cup makes contact down at the very bottom and around the very top.  Those are the only places that make contact.

The idea of the brass cup is to keep the injector cool.  Brass is used because it transfers heat the best.   The tip of the injector is right in the middle of the fire and keeping them cool is the key to having them last.  Set time on the Threadlocker is fairly quick.  You have to get it on there and get it knocked in the hole fairly quick.

You don’t need the biggest hammer you own to do this; a light tap is all you need until she bottoms out.   You will feel and hear it once it sets.  Now you can pull the installation tool out and your injector cup is installed.  Make sure you put the cap back on the Threadlocker so you have it next time.  If you don’t put the cap back on this stuff, it will harden inside within 24 hours.

This is what a nice new clean injector cup looks like installed in your cylinder head.  I like to get the injector nice and clean with new seals and installed as quickly as possible so it will hold the cup in place while the sealer is curing.  Once it is in there, even if you hustled it up, it will still be a couple hours until you are going to start the engine, which is plenty of time for the Threadlocker to seal.

With the truck back together, you are going to have replace hoses, and possibly water pump, thermostat, and all of the rubber seals that have been affected in the cooling system.  How long the fuel was in the coolant will determine how much damage was done to the cooling system.  I have seen some where we have had to put water pump, radiator, heater core, all the hoses, thermostat, because the problem had been there for a very long time.

In this situation, having the correct tools is absolutely crucial.  These are available on the internet.  I believe Snap-on can order them.  It is about $500 worth of tools to make this happen, but to do it right the first time, that is what it requires. ~Bill Hewitt