Posted on December 1, 2020 3176C, 3406E and 3456 Industrial Engines Troubleshooting – Coolant Contains Oil Probable Causes Oil cooler Cylinder head gasket Cylinder head Cylinder liner Cylinder block Recommended Actions Oil Cooler Check for leaks in the engine oil cooler core. If a leak is found, install a new oil cooler core. Refer to the Disassembly and Assembly manual. Check the driven equipment oil cooler (if equipped). Drain the crankcase and refill the crankcase with clean engine oil. Install new engine oil filters. Refer to the Operation and Maintenance Manual. Cylinder Head Gasket Remove the cylinder head. Refer to the Disassembly and Assembly manual. Check the cylinder liner projection. Refer to the Systems Operation/Testing and Adjusting manual. Install a new cylinder head gasket and new water seals in the spacer plate. Refer to the Disassembly and Assembly manual. Cylinder Head Check for cracks in the cylinder head. If a crack is found, repair the cylinder head and/or replace the cylinder head. Refer to the Disassembly and Assembly manual. Cylinder Liner Check for cracked cylinder liners. Replace any cracked cylinder liners. Refer to the Disassembly and Assembly manual. Cylinder Block Inspect the cylinder block for cracks. If a crack is found, repair the cylinder block or replace the cylinder block.