Nitro 2WD V6-4.0L (2007)
Coolant Reservoir: Description and Operation
Operation
Coolant Recovery Pressure System
COOLANT RECOVERY PRESSURE SYSTEM
As the engine warms, the coolant in the closed system expands. The pressurized bottle accepts the expanding fluid. Then, when the thermostat opens and
a high demand for coolant is placed on the system, the pressurized surge tank side of the bottle can supply the temporary additional volume of coolant
demanded by the system. Once the water pump catches up with the flow demand, the tank returns to equilibrium. A separate compartment in the bottle
accepts the overflow coolant which is then drawn back into the primary side of the bottle when the engine and coolant cool down
The advantage of the pressurized system is that any excess air in the cooling system is routed to the top of the bottle via a vent hose at the thermostat
housing to the bottle. This air accumulates at the top of the pressurized volume in the bottle (the highest point in the system) and is forced out of the
system through the pressure cap. This keeps the system properly deaerated and maintains pressure in the cooling system to prevent water pump cavitation
The diesel bottle has an additional vent line back to the radiator that is immersed in the coolant bath at the bottle. This also ensures air at the radiator is
routed back to bottle for expulsion and that a constant head of liquid is present at the radiator.
Coolant Recovery Non-Pressure System
COOLANT RECOVERY NON-PRESSURE SYSTEM
The coolant reserve/overflow system works in conjunction with the radiator pressure cap. It utilizes thermal expansion and contraction of coolant to keep
coolant free of trapped air. It provides a volume for expansion and contraction of coolant. It also provides a convenient and safe method for checking
coolant level and adjusting level at atmospheric pressure. This is done without removing the radiator pressure cap. The system also provides some
reserve coolant to the radiator to cover minor leaks and evaporation or boiling losses.
As the engine cools, a vacuum is formed in the cooling system of both the radiator and engine. Coolant will then be drawn from the coolant tank and
returned to a proper level in the radiator.
