Cooling System Operation - Jeep J-10 Series 1982 Technical & Service Manual

1C-1
COOLING
SYSTEMS
Piga
Coolant 1C-3
Coolant Recovery System 1C-14
Coolant Temperature Gauge 1C-15
Cooling System Diagnosis 1C-17
Cooling System Maintenance 1C-16
Cooling System Operation 1C-1
Cylinder Block Heater 1C-15
Drive Belt Adjustments 1C-24
Fan Assembly 1C-12
Fan Shroud 1C-14
GENERAL
The cooling system regulates engine operating tem
perature by allowing the engine to reach normal oper
ating temperature as soon as possible, maintaining
normal operating temperature and preventing over
heating (figs. 1C-1, 1C-2 and 1C-3). The cooling system
also provides a means of heating the passenger com
partment and cooling the automatic transmission fluid.
The cooling system is pressurized and uses a centri
fugal water pump to circulate coolant throughout the
system.
COOLING SYSTEM OPERATION
For four- and six-cylinder engines (with the engine
operating), the belt-driven water pump forces coolant
into the front of the cylinder block (adjacent to number
one cylinder) where water jackets route it around all the
cylinders. The coolant then passes upwards through
holes in the cylinder head gasket into the cylinder head
to cool the valve seats and valves. The coolant exits at
the front of the cylinder head into the thermostat hous
ing. If the coolant temperature is below 195°F (90°C),
the thermostat is closed and all coolant flows to the
front and through the intake manifold to assist fuel
vaporization. Coolant flows out the rear of the intake
manifold to the heater valve and (if open) to the heater
core. The coolant returns to the water pump from either
the heater core or heater valve (if closed) to be
recirculated.
Below 195°F (90°C) coolant does not flow through the
thermostat but flows to the front and through the intake
INDEX
Page
General
1C-1
Hoses 1C-9
Intake Manifold-
-Six-Cylinder Engine
1C-9
Radiator 1C-10
Serpentine Drive Belt Diagnosis
1C-27
Specifications
1C-30
Thermostat
1C-9
Tools 1C-35
Water Pump
1C-6
manifold. Above 195°F (90°C) part of the coolant flows
through the thermostat to the radiator and returns to
the pump inlet from the bottom of the radiator.
Heat from the coolant is used to warm the intake
manifold and assist fuel vaporization.
NOTE: The exhaust gas recirculating coolant temper
ature override (EGR CTO) valve and vacuum advance
CTO valve sensors are in contact with engine coolant.
For eight-cylinder engines, coolant is forced from the
center of the engine timing case cover through side out
lets into both banks of the cylinder block. It flows
through the water jackets around all cylinders and up
through holes in the cylinder block and head gaskets
into the cylinder heads to cool the valve seats and valves.
Coolant then flows through the cylinder heads to pas
sages at the front of the heads and through the intake
manifold to the thermostat. In the right cylinder head,
coolant is forced into an intake manifold passage at the
rear corner and out to the heater valve and heater core,
through the heater core (if the valve is open), and back to
the water pump. Below 195°F (91 °C), the thermostat is
closed and coolant flows out the bypass port through the
hose to the water pump, where it is recirculated.
For all engines, the recirculation cycle continues until
the coolant temperature reaches the thermostat calibra
tion temperature and the thermostat begins to open. A
portion of coolant then flows to the radiator inlet taok,
through the cooling tubes and into the outlet tank. The
radiator fan and vehicle motion cause air to flow past
the cooling fins to remove heat from the coolant. As the