Usage:
C-10 (2PN, 8YS, 3CS),
C-12 (1YN, 9NS, 2KS) Truck Engines
When investigating the cause of coolant in the engine oil, or high sodium levels found during engine oil sampling, first, remove the oil pan and pressure test the cooling system. Look for coolant leakage from the water pump seal or other locations in the engine. Removing the oil pan to inspect for coolant leakage is especially important on C-10 (2PN1-Up, 8YS1-02559) and C-12 (1YN1-Up, 9NS1-06949) Truck Engines. The water pumps on these truck engines have a smaller diameter weep hole than the 153-8053 Water Pump that is currently used in production on C-10 (8YS-02560-Up) and C-12 (9NS06950-Up) Truck Engines. The earlier water pump's weep hole is susceptible to becoming plugged with dirt. If the weep hole becomes plugged, coolant can leak into the engine instead of dripping out of the weep hole. Unless the oil pan is removed and the true cause of the internal leak is found, you may encounter unnecessary repairs that will not eliminate the internal leakage problem. Always remove the oil pan and pressure test the cooling system first.