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Posted by Rich on 11/15/11  ~  Posted in: Crack Repair and Detection

This is a brief "walk-through" of rebuilding the casting injector seat. If you have never done this kind of operation you should NOT use this information as your only instruction. This is meant to simply show the various tools in the order in which they are typically used and is intended for professional technicians who are already familiar with this process.



Tools used for this document are all contained in the Irontite Cummins ISX / QSX Injector Casting Repair Kit pictured above.

1) Remove the old injector sleeves

a) Using the Cummins sleeve remover, remove the old injector sleeve from the injector holes in the casting.

2) Suggested procedures to clean up any “casting distortion” and/or “sealing serrations”:

a)  In a machining center (seat & guide machine), using casting seat cutter (416-6156-28) with the driving arbor (414-6114-10) and the appropriate guide bushing (416-6156-32) clean up the casting seat with a .002 to .003 cut (.005 maximum).

b)  In cutting, the seat cutter should be operated at about 60/80 RPM and should be kept well lubricated at all times with our Irontite Tap-O (468-9920-08).

If removal of more casting material is required, then it is advised to install one of our taper threaded repair plugs in order to build up this casting seat area.

3) Preliminary Check

Frequently small cracks may appear on the face of the head at the injector hole area. If these cracks extend beyond the area that will be cover by the replacement plug, then these collateral cracks will need to be repaired. Their location on the face of the head should be clearly marked so they can be subsequently repaired using Irontite A-200 or A-235 Plugs.

It is important that this repair of these collateral cracks be done after the injector hole repair is completed and the replacement plug has been torqued into the injector hole. Otherwise, the torqueing in of the replacement plug might have a tendency to open up the collateral crack.

In some instances it may be desirable to drill a hole at the end of the collateral crack before starting the injector hole repair in order to relieve the casting stress at the collateral crack.

4) Enlarging the Injector Hole

With the pilot (416-6156-62) in the enlarging counterbore (434-6513-20), from the face side of the cylinder head, guide the pilot into the injector hole and cut out the injector area of the casting, it will then be ready for the tapered reamer and in turn the tapered tap.




NOTE: Unless cracks extend to the valve seat area, valve seats do not need to be removed during nose plug machining and installation.

5) Reaming the Injector Hole
With reamer (407-5213-10) and driver (449-6933-30) and coming from the face of the head, ream out the injector hole, operating the reamer at about 60/80 RPM. Do not ream too deep, just enough to get the tap started with a few threads is sufficient. Keep reamer well lubricated with Irontite Tap-O (468-9920-08)
or Irontite Micro Finish Tap & Lube (468-9910-16).




6) Tap the Injector Hole
With Tap (407-5313-30) tap the reamed hole for the installation of the “J” Plug. While tapping, keep the tap well lubricated with Irontite Tap-O (468-9920-08) or Irontite Micro Finish Tap & Lube (468-9910-16).




7) Install and Drill the Replacement Plug
Clean the tapped casting area and the “J” tapered plug with a quality cleaner. It is recommended to place Ceramic seal (468-9120-16) on the casting area along with the threads of the plug. Thread the plug into the casting and torque to 200 ft lbs of torque.

Turn the casting over, and coming in from the spring side of the casting, using the taper length drill (416-6156-26) and drill bushing (416-6156-19) drill the plug all the way through.


8)  Face off and peen the outer end of the plug
Turn the casting back over with the face up using the end facing counterbore ( 416-6156-61) and pilot (416-6156-62)  Face off the outer end of the replacement plug.  Bring it down to about 1/16” above the face of the casting.




Now peen the outer rim of the plug, always peening away from the center of the plug.  After peening the outer rim of the plug, smooth off the end of the plug.  If the head is to be resurfaced later, bring the end of the plug down to about 1/32” above the face of the head.  If there is not to be any later resurfacing of the head, then finish off the end other plug smooth with the face of the casting.

9)  Check for any collateral cracks
At this stage, after the plug has been installed, check the area around the plug to determine if any small cracks extend beyond the perimeter of the plug.  If so, these cracks should be now repaired, using the Irontite crack repair process.

After any such repair is completed, make certain that the surface of the head is smoothed as desired.

10)  Cut a new injector seat in the rebuilt area
Cut a new injector seat in the rebuilt injector seat area of the casting using the casting seat cutter (416-6156-28) along with the driving arbor (414-6114-10) and guide bushing (416-6156-32).




One very important feature in cutting the new seat is to cut it to the correct depth.  This seat depth is controlled by the use of the gage finger (433-6991-00) and the casting seat cutter gage (416-6156-29) in conjunction with the dimensional pilot at the end of the cutter.

Mount the gage finger on the casting with the flat surface of the gage finger directly below the injector hole.

Now, cut the new injector seat, bringing the cutter slowly down until the dimensional pilot at the end of the cutter bottoms on the casting seat cutter gage.

Here again a allowance must be made for any head resurfacing that may be contemplated later in the rebuilding process by shimming up the seat cutter gage on the gage finger accordingly.

In cutting, the seat cutter should be operated at about 60/80 RPM and should be kept well lubricated at all times with our Irontite Tap-O (468-9920-08)
or Irontite Micro Finish Tap & Lube (468-9910-16).

Irontite is a leading manufacturer of Carbide Casting Seat Cutters like the one used in this operation.  We work hard to make our Seat Cutters as precise and durable as possible for the best results.  You can see from this image, the detail in workmanship that goes into each and every product we make.



So when you need tooling for Diesel Repair or if you are dealing with Crack Detection, Irontite is

The Choice of Professionals Worldwide for Over 50 Years