Cooling System Components And Flow; Cylinder Block Diagram; Cylinder Head Diagram; Thermostat Diagram - Dodge D250 1990 Service Manual

Cooling System Components and Row
Page 7-2
Cooling System
Cooling System Components and Flow
The following illustration identifies the significant features of the coolant system.
1. Coolant is drawn from the radiator by the integrally mounted water pump. The output from the water pump
empties into the oil cooler cavity of the cylinder block.
2. The coolant then circulates around each cylinder and crosses the block to the fuel pump side of the engine.
3. Coolant then flows up into the cylinder head, crosses over the valve bridges and down the exhaust manifold
side of the engine to the Integral thermostat housing.
4. As the coolant flows across the head toward the thermostat housing, it provides cooling for the injector nozzle.
When the engine is below operating temperature, the thermostat is closed, and the coolant flow bypasses the
radiator and goes to the water pump inlet via internal drillings in the block and cylinder head.
When operating temperature is reached, the thermostat opens, blocking the bypass passage to the water pump and
opening the outlet to the radiator.
• Never operate the engine without a thermostat. Without a thermostat, the coolant will not flow to the radiator
and the engine will overheat.
Coding System
DODGE Turbo Diesel
B
6
Cylinder Block
1. Coolant Inlet
2. Pump Impeller
3. Coolant Flow Past
Oil Cooler
4. Coolant Flow Past
Cylinders
5. Coolant to Cylinder
Head
6. Transmission Oil
Cooler
7. Coolant Flow to
Transmission Oil
Cooler
8. Coolant Flow from
Transmission Oil
Cooler
It
II %
Cylinder Head
1. Coolant Flow from Cylinder Block
2. Coolant to Thermostat Housing
\ Thermostat
' Closed
1. Coolant Flow Past Injector 5.
2. Thermostat 6.
3. Coolant Bypass Passage
4. Coolant Flow to Pump Inlet
3 1
Open
Bypass Closed
Coolant Flow Back
to Radiator