Symptom
Combustion leaks can be identified by coolant overflowing from deaeration tank or air bubbles in the coolant.
Cause
• Failed injector sleeve
• Failed air compressor
• Failed head gasket
• Failed EGR cooler
• Porous or cracked cylinder sleeve
The likely cause of combustion gas leakage to the cooling system is past the injector sleeve in the cylinder head. A failed cylinder head gasket or porous / cracked cylinder sleeve is possible. However, this should not be considered unless there is evidence of engine overheating or high engine mileage without proper coolant conditioning.
Tools
• Radiator pressure testing kit
• Plastic surge tank cap adapter
• Cylinder head test plate
• Water supply housing pressure adapter
• Thermostat opening pressure adapter (cylinder head)
• Hose pinch-off pliers (2)
Procedure
1. Is the engine equipped with an air compressor?
• If yes, do step 2.
• If no, do step 3.
2. Close off both coolant hoses for the air compressor with hose pinch-off pliers. Test the system again.
• If coolant continues overflowing from the deaeration tank, do step 3.
• If coolant stops overflowing from deaeration tank, repair or replace the air compressor.
3. Remove injectors following the procedure in the Engine Service Manual.
4. Install radiator pressure tester with the appropriate adapter.
5. Pressurize cooling system to 96 kPa (14 psi).
6. Look for coolant leaking around the injector sleeve and into the cylinder bore.
• If a leak is noticed, replace the leaking injector sleeve and test again.
• If no leak is noticed, replace all six injector sleeves and test again.
• If coolant continues to flow into cylinders after all injector sleeves were replaced, do step 7.
7. Remove cylinder head from engine, perform all inspections, and pressure test cylinder head to verify leak path. Follow the procedure in the Engine Service Manual.
• Inspect cylinder head gasket for coolant leaks.
• Verify crankcase and cylinder head surface flatness using a straight edge and feeler gauge.
• Check cylinder liner protrusion.
8. Test the cylinder head with pressure test plate to validate the repair.
