SHAFT-AXLE 6G6407 - Caterpillar

Probable Causes
NOx Reduction System (NRS) cooler
Cylinder head gasket
Cylinder head
Cylinder blockRecommended Actions
Note: The procedures have been listed in order of probability. Complete the procedures in order.
Table 1
Troubleshooting Test Steps Values Results
1. NRS cooler
A. Check the NRS cooler for leaks for utilizing the "On Engine Test Procedure". Refer to Systems Operation, Testing, and Adjusting, "Exhaust Cooler (NRS) - Test".
NRS cooler
Result : The NRS cooler has a leak.
Repair: Replace the NRS cooler. Refer to the Disassembly and Assembly manual for the correct procedure.
Result : The NRS cooler does not have a leak.
Proceed to Test Step 2.
2. Cylinder head gasket leak
A. Check the cylinder head gasket for leaks.
Cylinder head gasket
Result : The cylinder head gasket is leaking.
Proceed to Test Step 3.
Result : The cylinder head gasket is not leaking.
Proceed to Test Step 3.
3. Cylinder head
A. Check for cracks in the cylinder head. Perform a leak test on the cylinder head. Refer to the Systems Operation, Testing, and Adjusting, "Cylinder Head - Inspect" for the correct procedure.
Cylinder head
Result : A crack is found in the cylinder head.
Repair: Repair the cylinder head or replace the cylinder head. Refer to the Disassembly and Assembly manual.
Proceed to Test Step 4.
Result : The cylinder head is OK.
Proceed to Test Step 4.
4. Cylinder Block
A. Check for cracks in top face of the cylinder block. Refer to the Systems Operation, Testing, and Adjusting, "Cylinder Block - Inspect" for the correct procedure.
Cylinder head
Result : A crack is found in the cylinder block.
Repair: Repair the cylinder block or replace the cylinder block. Refer to the Disassembly and Assembly manual.
Repair: Assemble the cylinder head with a new cylinder head gasket. Refer to the Disassembly and Assembly manual.
Result : The cylinder block is OK.
Repair: Assemble the cylinder head with a new cylinder head gasket. Refer to the Disassembly and Assembly manual.