80545M Mariner PROPELLER NUT

Probable Causes
Leaks in hoses or connections
Leaks in the radiator and/or expansion tank
Leaking heater core
Leaking water pump
Leaks in the engine oil cooler
Leaking core plug
Leaking cylinder head gasket Recommended Repairs
Leaks in Hoses or Connections
Check all hoses and check all connections for visual signs of leakage. If no leaks are seen, look for damage to hoses or loose clamps.Leaks in the Radiator and/or Expansion Tank
Pressurize the radiator and the expansion tank with the 9S-8140 Pressurizing Pump and check for leaks.Leaking Heater Core
Pressurize the cooling system with the 9S-8140 Pressurizing Pump and check for leaks.Leaking Water Pump
Check the water pump for leaks before starting the engine. Start the engine and look for leaks. If there are leaks at the water pump, repair the water pump or install a new water pump.Leaks in the Engine Oil Cooler
Check the engine oil cooler for external leaks. Repair the engine oil cooler or replace the engine oil cooler.Leaking Core Plug
Inspect the core plugs for leakage. Replace any leaking core plugs with a new core plug.Leaking Cylinder Head Gasket
Look for leaks along the surface of the cylinder head gasket. If you see leaks, install a new head gasket. Inspect the spacer plate for leakage. Tighten the bolts that hold the cylinder head to the proper torque according to the Specifications Manual.Coolant Leaks At The Overflow Tube
Probable Causes
Faulty pressure cap
Abnormally high coolant temperature
Insufficient expansion tank capacity
Leaking cylinder head gasket
Faulty fuel injection nozzle adapterRecommended Repairs
Faulty Pressure Cap
Check the sealing surface of the pressure cap for damage. Also check the sealing surface of the radiator for damage. Ensure that the cap is sealing correctly. Check the opening pressure of the pressure cap valve with the 9S-8140 Pressurizing Pump. Also check the sealing ability of the pressure cap valve with the pressurizing pump.Abnormally High Coolant Temperature
As the temperature of the coolant increases, the pressure inside the cooling system increases. When the coolant overheats, the pressure will overcome the sealing ability of the radiator cap. This will cause coolant loss through the overflow tube. If the temperature of the coolant is running too high, refer to Troubleshooting, "Coolant Temperature Above Normal".Insufficient Expansion Tank Capacity
The expansion tank can be a part of the radiator or the expansion tank may be a separate unit. The expansion tank capacity must be large enough to contain the coolant as the coolant expands. Ensure that the expansion tank is installed correctly. Ensure that the size meets the recommendations of the OEM.Leaking Cylinder Head Gasket
Remove the radiator cap while the engine is running. Look for air bubbles in the coolant. Bubbles in the coolant are an indication of a leak in the head gasket. Remove the cylinder head from the engine. Check the cylinder head and the cylinder liners for cracks. Check the head gasket surface of the cylinder block for cracks. Inspect the spacer plate for flatness. Install a new head gasket. Tighten the bolts that hold the cylinder head to the proper torque according to the Specifications Manual.Faulty Fuel Injection Nozzle Adapter
Check the fuel injection nozzle adapter for cracks. Inspect the fuel injection nozzle adapter's gasket for damage. Install a new fuel injection nozzle adapter's gasket and tighten to the proper torque. Refer to Disassembly and Assembly, "3406C Truck Engine".Internal Leaks
Probable Causes
Faulty fuel injection nozzle adapter
Leaking cylinder head gasket
Faulty cylinder liner O-ring sealRecommended Repairs
Faulty Fuel Injection Nozzle Adapter
Check the fuel injection nozzle adapter for cracks. Inspect the fuel injection nozzle adapter's gasket. Install a new fuel injection nozzle adapter's gasket and tighten to the proper torque. Refer to Disassembly and Assembly, "3406C Truck Engine".Leaking Cylinder Head Gasket
Remove the radiator cap while the engine is running. Look for air bubbles in the coolant. Bubbles in the coolant are an indication of a leak in the head gasket. Remove the cylinder head from the engine. Check the cylinder head and the cylinder liners for cracks. Check the head gasket surface of the cylinder block for cracks. Inspect the spacer plate for flatness. Install a new head gasket. Tighten the bolts that hold the cylinder head to the proper torque according to the Specifications Manual.Faulty Cylinder Liner O-ring Seal
Drain the crankcase and remove the oil pan from the engine. Pressurize the cooling system and inspect the cylinder liners for leaks. Refer to Disassembly and Assembly, "3406C Truck Engine".