Geely EC718, EC718RV, EC715, EC715RV. Manual part — 135

2.8 Cooling System JL4G18-D

2.8.1 Specifications
2.8.1.1 Fastener Tightening Specifications

Applications

Model

Specifications

Metric (Nm)

US English (lb-ft)

Long Water Pump Mounting Bolt

M6 × 35

9-13

6.7-9.6

Short Water Pump Mounting Bolt

M6 × 25

8-10

6-7.4

Engine Coolant Temperature Sensor

M12 × 1.5

16-24

12-17.7

Fan Assembly Mounting Bolt

M6 × 15

8-10

6-7.4

Fan Motor Retaining Nut

M10

10

7.4

Fan Motor Retaining Screw

M4 × 14

2.4

1.8

Radiator Retaining Bolts

M8 × 25

10-11

7.4-8.1

Coolant Recovery Reservoir
Retaining Bolts

M8 × 20

25

18.5

Engine Coolant Inlet Pipe Retaining
Nut

M6

9-13

6.7-9.6

Coolant Valve Component

M10 × 1

25 and above

18.5 and above

Engine Coolant Inlet Pipe Component

M6

9-13

6.7-9.6

2.8.1.2 Cooling System Specifications

Applications

Specifications

Cooling

Coolant

Engine Coolant Specifications / Grades

Comply with SH0521 (Freezing Point

≤-40°C /-40 ºF)

Engine Coolant Capacity (Coolant Recovery Reservoir)

6.5 L (11.44 pt)

Thermostat Type

Wax-Type Thermostat

Pump Type

Impeller

Blade Diameter

60 mm (2.36 in)

Blades

6

Thermostat Opening Temperature

82°C (179.6 ºF)

Thermostat Fully Open Temperature

95°C (203 ºF)

Low Speed Cooling Fan Turned On

95°C (203 ºF)

Low Speed Cooling Fan Turned Off

90°C (194 ºF)

High Speed Cooling Fan Turned On

102°C (215.6 ºF)

High Speed Cooling Fan Turned Off

97°C (206.6 ºF)

Engine

Cooling System JL4G18-D

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Applications

Specifications

Low Speed Cooling Fan Resistor

0.35 Ω

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Cooling System JL4G18-D

Engine

2.8.2 Description and Operation
2.8.2.1 Description and Operation

When engine is working, the mixture combustion in the cylinder
combustion chamber produces heat, which transfers through
the cylinder block. If it is not cooled, the engine will not work.
Inside the cylinder block, there is engine coolant path. Through
the engine coolant flow, heat exchanges with the outside
environment. This keeps the engine operating temperature
within a certain range, so that the engine can work effectively
in all operating conditions. When the engine is cooled, the
cooling system controls the engine coolant flow amount
through the thermostat. This makes the engine warm up
quickly. Cooling system includes radiator, coolant recovery
reservoir, cooling fan assembly, thermostat and housing, water
pump and water pump drive belt. The water pump is driven by
the accessory drive belt. Only when all the above components
work properly, can the cooling system to work properly. When
the engine coolant reaches the thermostat operating
temperature, the thermostat opens. At this point, the engine
coolant returns to the radiator and gets cooled. Cooling system
guides part of the engine coolant through the pipes into the
heater core, used for heating and defrost. Coolant Recovery
Reservoir is connected to the radiator assembly for recycling
discharged engine coolant, which is expanded due to the heat.
The Coolant Recovery Reservoir is to maintain the correct
engine coolant level.

Coolant Recovery Reservoir is a transparent plastic container,
similar to the windshield washer tank. Coolant Recovery
Reservoir connects to the engine cooling system and the
radiator through two separate pipes. With the vehicle driving,
the engine coolant temperature gradually increases and the
coolant expands. Part of the engine coolant flows from the
radiator into the coolant recovery reservoir as the result of
expansion. When the engine is shut down, the engine coolant
cools down and contracts, previously discharged engine
coolant flows back to the radiator and the engine. This makes
the engine coolant radiator maintain a suitable coolant level,
and improves cooling efficiency. When the cooling system is
cold, the engine coolant level should be kept between the MIN
(minimum) and MAX (maximum) marks in the coolant recovery
reservoir.

Cooling fan assembly is installed at the rear of the radiator in
the engine compartment. It increases radiator and Air-
Conditioning condenser air flow, and thus help accelerate the
cooling when idling or at low speed. There are dual fans, high
or low speed control modes controlled by two different motors.
Master fan diameter is 310 mm (12.20 in), auxiliary fan

diameter is 270 mm (10.63 in), both have five blades. Cooling
fan assembly is controlled by the engine control module (ECM)
using Low-Speed cooling fan relay and high speed cooling fan
relay. In the Low-Speed circuit, the series has a 0.35 Ω current-
limiting resistor. When the engine coolant temperature reaches
95°C (203 ºF), the engine control module enables Low-Speed
cooling fan assembly operation, and when the engine coolant
temperature reaches 102°C (215.6 ºF), it enables the High-
Speed cooling fan operation. When the temperature is back to
97°C (206.6 ºF), the engine cooling fan control module will
switch the cooling fan from high to low, when the temperature
drops to 90°C (194 ºF), the fan will be off.

Warning!

Even if the engine is not running, the cooling fan under
the engine compartment may still start and cause injury.
Keep hands, clothing and tools away from the cooling fan
under the engine compartment.

Warning!

If there is any degree of fan blades bending or damage,
do not repair or reuse the damaged parts. The bent or
damaged fan blades must be replace. Damaged fan
blades can not guarantee the normal balance and
continuous use, and may fly off, which is very dangerous.

Warning!

As long as there is cooling system pressure, even though
the solution in the radiator is not boiled, the solution
temperature will be much higher than the water boiling
point. If the engine is not cooled and the pressure is still
high, and the pressure cover is opened, the engine
coolant will be immediately boiled and will spray onto the
engine, fenders and the person opening the radiator
pressure cap.

Engine

Cooling System JL4G18-D

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2.8.3 System Working Principle
2.8.3.1 System Working Principle

–

Cold Engine: the engine normal operating temperature is
generally around 95°C (203 ºF), in this temperature range,
all the engine parts running status will be ideal. If the engine
can not reach the ideal operating temperature in a long
time,it will increase the parts wear and tear. Because of low
temperature, the mixture combustion will be inadequate,
and there will be excessive carbon residue. The engine
heat exchange must be kept minimum so the engine can
reach normal working temperatures in a short period of
time. At this point the thermostat controls the engine
coolant only circulates within the engine block, bringing the
heat from the cylinder wall to the other engine parts, so that
the temperature increases rapidly. Water pumps makes the
engine coolant flow in the cylinder block, then in the engine
block water jacket, throttle body and cylinder head cover.
This is called "small loop".

–

Engine at normal working temperature: With the engine
running, the engine coolant temperature quickly increases,
when the thermostat reaches 82°C (179.6 ºF), the engine
coolant is drawn into the engine block water jacket, intake
manifolds, cylinder head and radiator by the water pump.
This is called "big loop".

–

Thermostat: the thermostat's role is to control engine
coolant flow in the cooling system. Thermostat is installed
in the front of the engine and sealed by the engine intake
pipe joints components, located in the front of the cylinder
head cover. Thermostat can prevent the engine coolant
flow from the engine to the radiator, warm up the engine
quickly and adjust the engine coolant temperature. When
the engine coolant temperature is low, the thermostat in the
closed position, preventing the engine coolant circulating
through the radiator. At this point, it only allows the engine
coolant circulates through the heater core, and thus quickly
and evenly warm up the engine. When the engine is warm,
the thermostat opens. The engine coolant flows through
radiator and exchanges the heat. Thermostat opening and
closing, allow sufficient engine coolant enter into the
radiator, maintain the engine at normal operating
temperature range. The wax ball inside the thermostat is
sealed in a metal casing. Thermostat wax ball thermal
expands when warm and contracts when cold. As the
vehicle drives and the engine warms up, engine coolant
temperature increases. When the engine coolant reaches
the required temperature, the thermostat wax ball expands,
puts pressure on the metal shell and opens the valve. This
allows the engine cooling fluid flow through the engine
cooling system and engine cools down, when the wax ball
contracts, under the action of the spring, the valve will
close. Thermostat opening temperature is 82°C (179.6 ºF),
and fully open temperature is 95°C (203 ºF).

–

Cooling Fan Low-Speed Circuit Description: Engine cooling
fan circuit controls the main cooling fan and auxiliary
cooling fan. Cooling fan is controlled by the engine control
module (ECM) according to the engine coolant temperature
sensor and air pressure switch inputs. ECM monitors
conditions that meet the cooling fan Low-Speed running
conditions, ECM controls the engine wiring harness
connector EN01 terminal No.62 internal ground, and the
Low-Speed cooling fan relay pull-in. Power passes through
the low speed relay terminal No.87 to reach the cooling fan
wiring harness connector CA16 terminal No.1 and then
through the speed limit resistor, and finally reaches to the
paralleled two fan motors. Fan motors negative is
connected to the ground through the cooling fan wiring
harness connector CA16 terminal No.3. Therefore, the
Low-Speed fan motor starts running.

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Cooling System JL4G18-D

Engine