I thought I would post my experience with rebuilding my own injectors.

First a disclaimer: I am not a professional and far from it, just a DIY type of guy on a limited budget. Therefore I encourage any of the more knowledgeable people on this site to correct any errors in what I say or do and to add any information that I didn't include.

I purchased the 406 Injectors tool kit for this rebuild simply to be sure I had what I needed. It came in very handy, especially the holder that clamps into the vice and the 1/2 drive adapter plate for removing and installing the valve body.
The rebuild kit I used is also from 406 Injectors and is their deluxe kit.

Disassembly:

First step is to remove the exterior O-rings. A dental pick type tool works well to lift the o-ring so it can be cut with a razor blade.


The copper crush washer can be worked free with a razor knife:


Next the injector is placed in the vice holder. There is a pin that inserts through the side of the holder into the holes in the injector to hold it from spinning.


The solenoid screws are the first to be removed. Note: be sure to get a feel for how tight these screws are because the heads strip very easily if you over tighten them.


As you begin to remove these items pay special attention to the orientation. The solenoid connector faces the elongated area of the hold down clamp.
When the solenoid is removed you will see the spacer (note hole alignment runs in same direction as solenoid connector) and armature.


Once the spacer is removed you can check the armature clearance with a feeler gauge. I found it easier to do this on reassembly since that is when any spacers will be added.
Removing the Armature screw requires a special tool supplied in the kit. It is not very tight since it is a small diameter screw but you will need a wrench to hold it in place while removing. (Note the direction the Armature is facing for reassembly purposes.)


You will now see the top of the poppet valve that the armature screws into.
The four screws for the retainer will need to be removed. The poppet valve spring is compressed by the retainer so there will be some upward pressure. (Note the oil port must also face the elongated portion of the hold down clamp.)
When removing the poppet valve assembly from the valve body oil will leak out so wrap a rag or towel around the base of the injector.


On the underside of the poppet valve retainer is guide bushing and spacer that are held in place by an internal o-ring.
(Note: The poppet valve spring will be replaced so it can be discarded.)


Remove the internal o-ring and discard:


I placed all these parts into a basket that gets inserted into my Berry's Chemtool parts cleaner can. They will be soaked for at least and hour and then thoroughly cleaned using a spray can of carb cleaner to flush out internals and the small ports)

Next remove the valve body from the cap assembly using the supplied tool:


The intensifier piston is retained in the valve body by an internal o-ring. To get it out you will need to apply some air pressure to the the port in the poppet valve chamber.


In this next picture you will see the port I am referring to and the air gun I used. You just support the valve body in your had with a rag underneath to catch the intensifier piston when it comes out. Only a very short burst of air is required.



Once the piston is out you will need to remove the internal o-ring and the external o-ring on the valve body.


The portion remaining in the vice holder will contain a spring and plunger which will be reused.


Now you can remove the cap from the vice holder and remove the contents. This is where you need to pay very close attention to how the parts are assembled. I will detail reassembly later but for now getting a visual of the assembly will help.


Here it is laid out in assembly order:


There are four long pins and two short pins used in the assembly.
The short spring will be replaced as will the two check ***** that I will show in the next couple of pictures.
This is the barrel assembly:


The retaining band is removed the check ball discarded.


Next is the stop assembly. There is a plate on the top that retains the check ball and check plate. The ball will be replaced and can be discarded.


The next item is the spacer assembly. There is stop pin, nozzle spring and lift spacer inside.


Last is the nozzle and plunger:


All of these parts are thoroughly cleaned.
Using the plastic tube on the carb cleaner spray can will let you check that all the nozzle ports are clear and functioning.
The valve body and cap will need to have the o-ring grooves cleaned on a wire wheel.

Assembly:

With everything clean I began reassembly by placing the cap on the table to use as holder while assembling the internals.

First the nozzle and plunger (Note: I cover these with WD40 during installation.)


Next is the short locating pins:


The spacer sleeve is then installed on the pins and then the lift spacer is inserted into the sleave. There is really only one way to install these. If unsure hold it up to the light and you see only one hole goes all the way through, put the pins in the other two holes.


Install the new spring and stop pin:




Install two long locating pins and the stop body facing upward with the check plate installed and a new check ball.


Install the stop plate:


Next the barrel assembly with a new check ball installed:


Now remove the entire assembly from the cap and carefully balance it on your finger while inserting it into the cap.


Insert into the cap and then place into the vice holder. Once in the holder you will want to grab the nozzle and turn it to make sure the entire internal assembly spins with the nozzle.




Using needle nose pliers insert the last two locating pins:


Install plunger and spring:


You will now need to install the intensifier piston internal o-ring. I dipped this in motor oil and found that if you can get the leading edge to start into the groove the rest will follow as you push it into place. I used a plastic tool so as not to damage the o-ring.


Dip the intensifier piston in motor oil and install into valve body. You will need to push this all the way in to help with installation of body to cap.


Coat the outer o-ring in motor oil and install on the valve body.

Now pour a small amount of motor oil over the spring and plunger assembly, then carefully place the valve body onto the cap. You can lift up on the nozzle slightly with your finger to help align the locating pins on the barrel with the valve body. Begin screwing the valve body into the cap by hand making sure the nozzle is turning at the same time. Use the adapter plate and torque to 70 ft lbs.


Next you will need to install the internal o-ring into the poppet retainer:



Dip the poppet guide into motor oil and install the spacer and guide into the retainer:


Dip the poppet valve in motor oil, install new spring and then insert into valve body.
Fill the chamber with motor oil and then install the hold down clamp with the elongated end opposite the poppet chamber port recess as pictured. Install the poppet valve retainer by applying downward pressure to compress the poppet valve spring and inserting screws. (Note: the oil port on the retainer should also point to the elongated end of the clamp.)




(Note: I installed the poppet valve assembly in the orientation above because that is what it looked like when taken apart. Not sure if it makes any difference.)

Install the Armature and check clearance. I strove to get .003" minimum or a tight .004" clearance.



If you need to add a spacer, remove the Armature and put it over the screw.


Install spacer with holes aligned with retainer port.
Then install solenoid with connector toward elongated end of hold down clamp. Remember the armature must run in the same direction as the magnetic surfaces of the solenoid. Don't over tighten solenoid screws as they will strip easily.


Remove injector from holder and invert on table, then install external o-rings making sure they aren't twisted when installed.
Install the new crush washer (I used a socket to press it on with) and you are done.

Finished product:

 

Amazing job! Reps sent Jim. We all look forward to you reporting back soon about their performance.

 

Reps sent, great job and write up and I'm also looking forward to the follow up. I hope it's 100% a winner.

 

Subscribing. Been thinking about doing that to mine since they are the originals.

 

I am anxious as well to get this truck running again. My thoughts are that it will run considerably quieter and that my cold starts won't be so rough anymore. #2 had failed the Buzz test and I couldn't get a .002" shim to even start under the edge of the armature.

Also found that the top injector bolts were all under torqued. A couple of them were just above finger tight and the rest were maybe 40 in lbs. Cleaned up the threads and using blue loctite I reinstalled and torqued to 125 in lbs.

The glow plugs are fairly new and all looked like they were operating just fine.

Wish I could hurry the mail system up a bit.
While waiting for the replacement core I plan to do some clean up work and inspection of the wiring and connectors.

 

There is a school of thought (of which I am a member of the class) that the injector bolts are not coming loose but rather, the injector is sinking deeper into the hole, which results in the bolts not being as tight.
Loctite won't remedy that issue.

 

The problem with that theory is the injector sinking into the hole isn't going to reduce the torque on the upper bolt since the clamp rides on the shoulder of the bolt not the threads. At least in my way of thinking.

The injectors were completely out of the truck when I checked the upper bolts.

 

Aaaaaa ok on the upper bolt, I missed that part.

 

Reps sent, thanks for the picture write up as well. Hope they run as smooth as your job went. Wonder if the rebuilders change any other parts then you did.

 

Reps sent, looks simple from this end. But how are you too do about a flow test? Just curiou or is it not necessary?

 

I guess my flow test will be when I fire it up.

Once it is up and running I will give a report on difference in cold starting, mpg and performance.

 

Jim, which tool are you using to remove and install the injectors? There are a couple different flavors out there, would be good to know what you are using, since you are very brave to rebuild your own injectors.

 

I used a flat ended pry bar that I use in carpentry work.
To install them I held the back of the injector with my left hand applying slight pressure toward the intake while holding the clamp forward and then tapped on the center of the solenoid with a soft faced dead blow hammer until it seated.
There is a very distinct sound when the crush washer makes contact.

If there is a better way I am all for it. Had some trouble with the injectors at the back of the engine because of the tight space.

 

Superb!

I can offer some tips on the basics.

1. I use these pry bars. I believe it is the #3 out of 4 (not largest) in size



Remove your UVCH and valve cover gasket (if separate) first. Remove lower injector bolt completely (lay them out by number/position to keep all mating pieces together).

Use one hand below injector and slide the big retainer bracket upwards so the bigger part of the hole slides out from under the upper bolt head. While holding it there, place edge of pry bar under a meaty part of that bracket where it won't hit anything and securely place bend of the bar on the surface of the head where it won't slip.

Ensure you have enough room to push the handle down, each injector requires a slightly different angle/position.

Pry on the bar a bit and make sure your bracket isn't getting hung up on the bolt or anything. I usually make two pry efforts. One to clear the bolt head, then another to finish the removal. Hold the bracket the whole time. It's safer.

Be sure you have firm and solid placement of your bar. You don't want to slip and hit the injector or something else on your truck.

2. Injector top 4 bolts. I believe they are T-10 (?) torx. I HIGHLY recommend a battery impact/driver, very LIGHTLY bumped to break them free. Hold it in very straight an square with firm force.

This is the one I use, with the socket, not the square socket end. Very minimal force is needed. (Not sure what that plastic hanger is, stock pic)



I use a socket adapter and torx socket, though they do make torx bits for the drivers, too. I just don't have that set handy.






I had started with a ratchet, but it was clear that despite my best efforts it was going to slip/strip. Changed to the above and a very firm and square hold and a light bump and they were broken loose, then removed by removing the bit from the driver and spinning by hand.

3. Paint pen is what I used to maintain orientation on the armature plate and such. It wipes off easily with cleaner. Only takes a dot.

4. Internal oring installs. Slickest thing I saw when I struggled with an internal oring in a hydraulic cylinder rebuild was a too with three fingers on it. Two go inside the oring, one outside that rolls between the outside ones and moves towards the center of the circle. Sort of pinches but not kinks the oring, reducing its diameter slightly to aid installation.

This is similar, though it shows the outer fingers rotating about the middle and going outwards. Same difference I suppose.



A similar result can be had using curved opened forceps for the outer fingers and a small rod in between, used like chopsticks except squeezing the tops together moves the rod in between the forceps' fingers jaws.

5. Reinserting injectors into the tight back spots is easier if you use a small block of 2x4, maybe 10-12 inches long and a rubber mallet.

Soak the injectors in a cutoff jug of new oil for a minute or so, near the injector hole, and lift it out and with a rag under but not touching the injector, insert it straightaway into the hole and get it started by hand.

To complete the install, firmly brace the end of the 2x4 on the center of the solenoid, as straight aligned with the injector as space allows. Hold it firmly not to slip, smack the top end of the 2x4 with the mallet. It makes a distinct sound when firmly seated, learn to recognize it

This trick was recently taught to me by a buddy who helped with my injectors. HUGE help Be careful and bear in mind you don't want to damage the injectors or orings. Multiple small but firm strikes are better than a sledgehammer blow

6. Before reinstalling the valve covers, make sure all your harness wires are down inside the lip of the head (no pinching of wires allowed), and they all clear the rocker arms and push rods. I like to make a downward bend in the glowplug wires especially. Takes up slack and keeps some tension on the wires to hold them downward. (a dip in the slack of the wire instead of tucked to the side or something else)

Maybe some of these tips can help

Again, superb writeup, thanks! Reps sent

 

My injector core still hasn't arrived so no updates. Hoping it arrives by Monday afternoon.
The wait is killing me.