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The CAT D6C and Its Radiator Core Configuration
The Caterpillar D6C dozer, produced during the 1960s and 1970s, was a mid-size crawler built for grading, pushing, and land-clearing tasks. It featured a rugged design, mechanical simplicity, and a reputation for reliability in harsh conditions. Powered by a six-cylinder diesel engine, the D6C was widely adopted across construction, forestry, and agricultural sectors. Caterpillar, founded in 1925, had by then become the global leader in earthmoving equipment, and the D6 series was one of its most successful product lines, with tens of thousands of units sold worldwide.
One of the key components in the D6C’s cooling system is the radiator core—specifically, the 4N-6298 core, which is used across multiple serial number ranges. This core requires precise gasket matching to ensure proper sealing between the top and bottom tanks. However, discrepancies in parts manuals and dealer databases have led to confusion and misidentification of the correct gasket part numbers.
Serial Number Conflicts and Gasket Mismatch
The issue often arises when the parts manual or dealer system recommends a gasket that physically does not match the radiator core’s bolt pattern or dimensions. For example, part number 6N-4950 is commonly listed for machines with serial numbers 10K8969 and above. However, for machines in the 10K7953 to 10K8968 range, the correct gasket is 1P-2520—even though both are associated with the same 4N-6298 radiator core.
This discrepancy suggests that while the core remains consistent, the tank configuration or bolt layout may differ slightly between serial number ranges. In one case, a gasket labeled 6N-4950 was twice the size of the required part and had too many bolt holes, rendering it unusable.
Common gasket part numbers for the 4N-6298 core:
Parts cross-referencing systems are designed to simplify ordering, but they can introduce errors when older machines are involved. Many of these systems were digitized from microfiche or paper catalogs in the 1980s and 1990s, and optical character recognition (OCR) mistakes may have corrupted part numbers or descriptions.
In some cases, a part number like 1P-2520 may be listed as superseding 6N-4950, implying interchangeability. However, physical differences in gasket shape, bolt count, or thickness can make them incompatible. One technician noted that even a cross-referenced gasket shrunk by nearly an inch due to age and storage conditions, further complicating fitment.
To avoid misidentification:
When the correct gasket cannot be sourced, operators sometimes resort to fabricating their own using rubber sheet stock. A roll of 1/8" nitrile or neoprene rubber can be cut to match the flange pattern using a cardboard template. While not ideal for high-pressure applications, this method can provide a temporary seal for low-pressure radiator tanks.
Fabrication steps:
The Importance of Serial Number Accuracy
Caterpillar machines rely heavily on serial number identification to match parts correctly. Even a single digit error can result in the wrong gasket, filter, or seal. The D6C’s serial number prefix “10K” must be followed by the full six-digit sequence to determine the correct configuration.
Tips for accurate parts ordering:
Conclusion
Ordering parts for legacy Caterpillar machines like the D6C requires more than just a part number—it demands attention to serial number ranges, physical verification, and sometimes creative problem-solving. When manuals and dealer systems conflict, field experience and careful inspection become the most reliable tools. Whether sourcing a gasket or rebuilding a radiator assembly, precision and patience are key to keeping these classic machines running strong.
The Caterpillar D6C dozer, produced during the 1960s and 1970s, was a mid-size crawler built for grading, pushing, and land-clearing tasks. It featured a rugged design, mechanical simplicity, and a reputation for reliability in harsh conditions. Powered by a six-cylinder diesel engine, the D6C was widely adopted across construction, forestry, and agricultural sectors. Caterpillar, founded in 1925, had by then become the global leader in earthmoving equipment, and the D6 series was one of its most successful product lines, with tens of thousands of units sold worldwide.
One of the key components in the D6C’s cooling system is the radiator core—specifically, the 4N-6298 core, which is used across multiple serial number ranges. This core requires precise gasket matching to ensure proper sealing between the top and bottom tanks. However, discrepancies in parts manuals and dealer databases have led to confusion and misidentification of the correct gasket part numbers.
Serial Number Conflicts and Gasket Mismatch
The issue often arises when the parts manual or dealer system recommends a gasket that physically does not match the radiator core’s bolt pattern or dimensions. For example, part number 6N-4950 is commonly listed for machines with serial numbers 10K8969 and above. However, for machines in the 10K7953 to 10K8968 range, the correct gasket is 1P-2520—even though both are associated with the same 4N-6298 radiator core.
This discrepancy suggests that while the core remains consistent, the tank configuration or bolt layout may differ slightly between serial number ranges. In one case, a gasket labeled 6N-4950 was twice the size of the required part and had too many bolt holes, rendering it unusable.
Common gasket part numbers for the 4N-6298 core:
- 6N-4950: For later serial numbers (10K8969-up)
- 1P-2520: For earlier serial numbers (10K7953–8968)
- 1P-9178: Often used for bottom tank sealing
- 1P-2512 and 1P-2680: Associated with top tank plate assemblies
Parts cross-referencing systems are designed to simplify ordering, but they can introduce errors when older machines are involved. Many of these systems were digitized from microfiche or paper catalogs in the 1980s and 1990s, and optical character recognition (OCR) mistakes may have corrupted part numbers or descriptions.
In some cases, a part number like 1P-2520 may be listed as superseding 6N-4950, implying interchangeability. However, physical differences in gasket shape, bolt count, or thickness can make them incompatible. One technician noted that even a cross-referenced gasket shrunk by nearly an inch due to age and storage conditions, further complicating fitment.
To avoid misidentification:
- Always verify gasket dimensions before installation
- Count bolt holes and compare to the tank flange
- Consult legacy paper manuals when digital sources conflict
- Contact multiple suppliers to confirm part compatibility
When the correct gasket cannot be sourced, operators sometimes resort to fabricating their own using rubber sheet stock. A roll of 1/8" nitrile or neoprene rubber can be cut to match the flange pattern using a cardboard template. While not ideal for high-pressure applications, this method can provide a temporary seal for low-pressure radiator tanks.
Fabrication steps:
- Trace the flange pattern onto cardboard
- Transfer to rubber sheet and cut with utility knife
- Punch bolt holes using gasket punch set
- Apply non-hardening sealant to both sides before installation
The Importance of Serial Number Accuracy
Caterpillar machines rely heavily on serial number identification to match parts correctly. Even a single digit error can result in the wrong gasket, filter, or seal. The D6C’s serial number prefix “10K” must be followed by the full six-digit sequence to determine the correct configuration.
Tips for accurate parts ordering:
- Record the full serial number from the data plate
- Cross-check with engine and frame serial numbers
- Use legacy manuals when available
- Avoid relying solely on dealer databases for older machines
Conclusion
Ordering parts for legacy Caterpillar machines like the D6C requires more than just a part number—it demands attention to serial number ranges, physical verification, and sometimes creative problem-solving. When manuals and dealer systems conflict, field experience and careful inspection become the most reliable tools. Whether sourcing a gasket or rebuilding a radiator assembly, precision and patience are key to keeping these classic machines running strong.
