CYLINDER HEAD AS 4952730 - Caterpillar

Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.Problem
Certain remanufactured engine long blocks and engine cylinder heads have improperly installed core plugs. These core plugs will loosen during engine operation causing flooding of the engine with coolant, and engine failure. The affected parts were built prior to 1April 2012. The complete engine serial number prefixes that are affected are KCM, and LET. The following long block part numbers must be inspected: 20R-0163, 20R-0182 and 20R-0763. Only engines and long blocks using remanufactured 357-7396 Cylinder Head casting are affected.The 357-7396 Cylinder Head casting has a 6 mm (0.24 inch) deep step in the bore where the core plugs are inserted near the rocker stands. This requires that the cup plugs be installed deeper into the cylinder head. Cylinder heads must be inspected and reworked if shallow plugs are found. Solution
Inspection of remanufactured complete engines and long blocks should be done for components that were built prior to 1April 2012. The start date of the problem is unknown, but is expected to be no earlier then November 2011. However, the only known failure occurred after five hours of engine operation, and few affected engines are currently in the field.
Illustration 1 g03052516
Close-up view of part number on cylinder headThe cylinder head part number is cast externally, and is visible between the valve cover bolts near the number 2 inlet port (from left, inlet port at top). Refer to Illustration 1.
Illustration 2 g03052520
View of new bore with step
Illustration 3 g03055216
Close-up view of core plug at correct depthInspect the core plugs for the proper depth. If the depths of the core plugs are 1.5 mm (0.06 inch) from the surface of the cylinder head or less, the core plugs must be removed and reinstalled to the proper depth.Procedure for Removal and Installation of Core Plugs
Drain the coolant from the engine.
Remove the valve cover, and rocker assembly in order to expose the core plugs.
Remove the core plugs.
Clean out old sealant from the plug bore.
Install the new 3B-0623 Cup Plug with blue Loctite item number 11358. Drive the core plug to a depth of 7 mm (0.28 inch) from the surface of the cylinder head. The core plug must be at least 1 mm (0.04 inch) past the step.
Reassemble the valve cover, and rocker assembly.
Fill coolant. Refer to Operation and Maintenance Manual for more information.
Contact a Caterpillar Reman representative in order to get labor for reworking under parts warranty.