09130-05851 GOVERNOR ASSY, MEC Denso Cross

Coolant Leaks At The Overflow Tube
Possible Causes/Corrections Defective Pressure Cap Or Relief ValveCheck the sealing surfaces of the pressure cap and the radiator to be sure the cap is sealing correctly. Check the opening pressure and sealing ability of the pressure cap or relief valve with the 9S8140 Cooling System Pressurizing Pump Group. Engine Runs Too HotIf coolant temperature is too high, pressure will be high enough to move the cap off of the sealing surface in the radiator and cause coolant loss through the overflow tube. See "Overheating" in Cooling System Troubleshooting Section. Expansion Tank Too Small Or Installed WrongThe expansion tank can be either a part of the radiator or it can be installed separately from the radiator. The expansion tank must be large enough to hold the expansion of the coolant as it gets warm or has sudden changes in pressure. Make sure the expansion tank is installed correctly, and the size is according to the recommendations of the truck manufacturer. Cylinder Head Gasket Leakage Or Crack(s) In Cylinder Head Or Cylinder BlockRemove the radiator cap and, with the engine running, look for air bubbles in the coolant. Bubbles in the coolant are a sign of probable leakage at the head gasket. Remove the cylinder head from the engine. Check cylinder head, cylinder walls and head gasket surface of the cylinder block for cracks. When the head is installed, use a new head gasket, spacer plate gasket, water seals, and O-ring seals.Inside Leakage
Possible Causes/Corrections Cylinder Head Gasket LeakageIf the cylinder head gasket leaks between a water passage and an opening into the crankcase, coolant will get into the crankcase. Crack(s) In Cylinder HeadCrack(s) in the upper surface of the cylinder head, or an area between a water passage and an opening into the crankcase, can allow coolant to get into the crankcase. Crack(s) In Cylinder BlockCrack(s) in the cylinder block between a water passage and the crankcase will let coolant get into the crankcase.