106871-4375 ZEXEL F 019 Z20 252 BOSCH INJECTION-PUMP ASSEMBLY f019z20252 1068714375

COOLING SYSTEM FLOW DIAGRAM
1. Cylinder head. 2. Aftercooler. 3. Water temperature regulator housing. 4. Coolant outlet from radiator. 5. Air compressor. 6. Bypass water line. 7. Coolant outlet to aftercooler. 8. Water manifold. 9. Coolant outlet to water manifold. 10. Cylinder block. 11. Oil cooler. 12. Coolant inlet to water pump. 13. Water pump. 14. Shunt line. 15. Radiator. 16. Vent line. 17. Upper chamber. 18. Bleed tube. 19. Lower chamber.This engine has a pressurized cooling system. Coolant is circulated by a belt driven, centrifugal type water pump. A water temperature regulator, located at the left front of the cylinder head, restricts coolant flow through the radiator until the coolant reaches operating temperature.The water pump has two outlets. One outlet directs coolant through a passage in the water temperature regulator housing to the aftercooler, to lower the temperature of inlet air in the inlet manifold. The other water outlet directs coolant through a water manifold in the side of the cylinder block, to cool engine lubricating oil. Coolant flows from the water manifold around the cylinder liners, into the cylinder head and around the precombustion chambers. Both streams of water join at the water temperature regulator.The water cooled air compressor receives coolant through a tube that is connected to the water manifold in the side of the cylinder block. Coolant returns through a tube from the air compressor head to the diesel engine cylinder head.Until the coolant reaches the temperature required to open the temperature regulator, coolant bypasses the radiator and flows directly back to the water pump.When the coolant reaches the temperature required to open the temperature regulator, coolant is then directed to the radiator lower chamber.The upper chamber of the radiator receives any air in the lower chamber by way of the bleed tube. Any air in the engine is vented to the radiator upper chamber thru the vent line. The shunt line from the upper chamber to the inlet of the water pump provides for rapid filling of the system.A pressure relief cap assembly is used to control the pressure in the cooling system, and prevents loss of coolant through the radiator overflow tube.Pressurizing the cooling system serves two purposes. First, it permits safe operation at coolant temperatures higher than the normal boiling point, providing a margin of cooling for intermittent peak loads. Secondly, it prevents cavitation in the water pump, and reduces the possibility of air or steam pockets forming in the coolant passages. Proper operation of the pressure relief cap assembly is essential. A pressure relief cap allows pressure (and some water, if the cooling system is too full) to escape when the pressure in the cooling system exceeds the capacity of the pressure cap. Loss of pressure will cause steam to form when coolant temperature is above the normal boiling point.Cooling System Components
Water Pump
The centrifugal-type water pump has two seals, one prevents leakage of water and the other prevents leakage of lubricant.An opening in the bottom of the pump housing allows any