Usage:
D399 Engines (35B1275-2618 and 91B628-924);
G399 Engines (49C348-538)
- SUPPLEMENT: 05/12/80
SERVICE MAGAZINE, APRIL 23, 1979, PAGE 6 AND 7. The article "Inspection Of Oil Pump After Long Periods Of Service Can Prevent Engine Damage" gave a specific range of serial numbers for D399 and G399 Engines on which the oil pump needed to be inspected after long periods of service. This recommendation is now extended to all D399 and G399 Engines that have the serial number prefixes shown.
Also, if S.O.S. tests show more than normal amounts of steel in the oil and/or if there is excessive (too much) gear noise from the oil pump, remove the pump and disassemble it to check for damage.
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New oil pump assemblies with a higher capacity were used on the above engines for better lubrication. Later improvements were made to these pumps for better internal (inside) lubrication, and the gear hardness was increased for longer service life. Later pump assemblies shown in the parts chart have other improvements, and/or can be used with a shut-off attachment.
On engines with the serial numbers shown that have the original pump assemblies, some pitting of the gear teeth is possible after long periods of service. The recommendation is to inspect the oil pump after approximately 10,000 hours of engine operation. If the gear teeth are badly pitted, install a new shaft assembly and gears. If the end cover, body and manifold are badly damaged, a new pump assembly will be needed. The parts chart shows components of the original pump assembly, which can be ordered for replacement of worn parts. All the parts shown have the latest design improvements, but the part numbers did not change. Inspection of the oil pump, and repair if necessary, can prevent high cost damage to the engine.
