PAWL 3082674 - Caterpillar

3406, 3406B, 3408 Truck EnginesOn the above Truck Engines, some head bolt holes in the cylinder block may have worn or damaged threads. Here is a salvage procedure that can be used to replace the threads and reuse the block.
Remember, this procedure is limited to the repair of only two bolt holes in each block head face (or bank), and to only one hole per cylinder bolt pattern (six holes per pattern). Various Heli-Coil ® installation tools are used. Do NOT use the oversize Heli-Coil Twinsert Inserts to repair these holes.
The first three machining steps, counterboring, drilling, and retapping in that order, are shown in the illustration. Next, check the threads with Gauge No. 1441-12 to a depth of 2.62 ". Then, install No. 1191-12 CN by 1.5" Heli-Coil Insert to a depth of 1.105 " to 1.111" deep.
Drilling and tapping prior to installation of the Heli-Coil insert in the head bolt hole.The special tap and the thread gauge are included in the Heli-Coil insert kit.