Kymco MO GD125, MO GD 150 Service Manual - chap 12 (raffreddamento)

12. COOLING SYSTEM

12-0

GRAND DINK 125/ 15 0

12

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COOLING SYSTEM

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SCHEMATIC DRAWING ---------------------------------------------- 12- 1

SERVICE INFORMATION -------------------------------------------- 12- 2

TROUBLESHOOTING ------------------------------------------------- 12- 2

COOLING SYSTEM TESTING --------------------------------------- 12- 4

RADIATOR -------------------------------------------------------------- 12- 4

WATER PUMP ---------------------------------------------------------- 12- 9

THERMOSENSOR ------------------------------------------------------ 12-15

THERMOSTAT---------------------------------------------------------- 12-16

12

12. COOLING SYSTEM

12-1

GRAND DINK 125/ 15 0

SCHEMATIC DRAWING

Torque: 9.8_ 13.7N-m

Left Hand Threads

＊

12. COOLING SYSTEM

12-2

GRAND DINK 125/ 15 0

SERVICE INFORMATION

GENERAL INSTRUCTIONS

• The water pump must be serviced after removing the engine. Other cooling system service can be

done with the engine installed in the frame.

• The engine must be cool before servicing the cooling system.

When the coolant temperature is over 100℃ , never remove the radiator cap to release the
pressure because the boiling coolant may cause danger.

• Avoid spilling coolant on painted surfaces because the coolant will corrode the painted surfaces.

Wash off any spilled coolant with fresh water as soon as possible.

• After servicing the system, check for leaks with a cooling system tester.

SPECIAL TOOL

Mechanical seal driver

TORQUE VALUES

Water pump impeller 9.8_ 13.7N-m
Water pump cover bolt 7.8_ 11.8N-m

TROUBLESHOOTING

Engine temperature too high Coolant leaks

• Faulty temperature gauge or thermosensor • Faulty pump mechanical (water) seal

• Faulty radiator cap • Deteriorated O-rings

• Faulty thermostat • Damaged or deteriorated water hoses

• Insufficient coolant

• Passages blocked in hoses or water jacket

• Clogged radiator fins

• Passages blocked in radiator

• Faulty water pump

Temperature gauge pointer does not register
the correct coolant temperature

• Faulty temperature gauge or thermosensor

• Faulty thermostat

12. COOLING SYSTEM

12-3

GRAND DINK 125/ 15 0

SPECIFICATIONS

Radiator cap relief pressure

0.9±0.15kg/cm_

Begins to open

80±2℃

Thermostat temperature

Full-open

90℃

Valve lift

3.5_ 4.5mm

Coolant capacity

Total system

1400±20cc

Radiator: 1000±20cc
Reserve tank: 400±20cc

COOLANT GRAVITY

Temp. ℃

Coolant
concentration

05101520253035404550

5%

1.009

1.009

1.008

1.008

1.007

1.006

1.005

1.003

1.001

0.009

0.997

10%

1.018

1.107

1.017

1.016

1.015

1.014

0.013

1.011

1.009

1.007

1.005

15%

1.028

1.027

1.026

1.025

1.024

1.022

1.020

1.018

1.016

1.014

1.012

20%

1.036

1.035

1.034

1.033

1.031

1.029

1.027

1.025

1.023

1.021

1.019

25%

1.045

1.044

1.043

1.042

1.040

1.038

1.036

1.034

1.031

1.028

1.025

30%

1.053

1.051

1.051

1.049

1.047

1.045

1.043

1.041

1.038

1.035

1.032

35%

1.063

1.062

1.060

1.058

1.056

1.054

1.052

1.049

1.046

1.043

1.040

40%

1.072

1.070

1.068

1.066

1.064

1.062

1.059

1.056

1.053

1.050

1.047

45%

1.080

1.078

1.076

1.074

1.072

1.069

1.056

1.063

1.062

1.057

1.054

50%

1.086

1.084

1.082

1.080

1.077

1.074

1.071

1.068

1.065

1.062

1.059

55%

1.095

1.093

1.091

1.088

1.085

1.082

1.079

1.076

1.073

1.070

1.067

60%

1.100

1.098

1.095

1.092

1.089

1.086

1.083

1.080

1.077

1.074

1.071

COOLANT MIXTURE (WITH ANTI-RUST AND ANTI-FREEZING EFFECTS)

Freezing Point

Mixing Rate

KYMCO SIGMA Coolant Concentrate

Distilled Water

-9℃

20%

-15℃

30%

425cc

975cc

-25℃

40%

-37℃

50%

-44.5℃

55%

Cautions for Using Coolant:

• Use coolant of specified mixing rate. (The

mixing rate of 425cc KYMCO SIGMA
coolant concentrate + 975cc distilled
water is 30%.)

• Do not mix coolant concentrate of

different brands.

• Do not drink the coolant which is

poisonous.

• The freezing point of coolant mixture shall

be 5℃ lower than the freezing point of
the riding area.

12. COOLING SYSTEM

12-4

GRAND DINK 125/ 15 0

COOLING SYSTEM TESTING

RADIATOR CAP INSPECTION

Install the radiator cap onto the radiator
tester and apply specified pressure to it. It
must hold specified pressure for at least six
seconds.

Radiator Cap Relief Pressure:

0.9±0.15kg/cm_

Install the radiator tester onto the radiator
and apply specified pressure to it. It must
hold specified pressure for at least six
seconds.
Check the water hoses and connectors for
leaks.

RADIATOR

RADIATOR INSPECTION

Remove the front upper cover. (!2-5)
Remove the front lower cover. (!2-5)

Radiator Cap

Radiator Tester

The test pressure should not exceed 1.05
kg/cm_. Excessive pressure can damage
the radiator and its hose connectors.

＊

Apply water to the cap sealing surface
before testing.

＊

12. COOLING SYSTEM

12-5

GRAND DINK 125/ 15 0

Inspect the radiator soldered joints and
seams for leaks.
Blow dirt out from between core fins with
compressed air. If insects, etc., are clogging
the radiator, wash them off.
Carefully straighten any bent fins.

RADIATOR REMOVAL

Drain the coolant. (!3-9)
Disconnect the air vent tube from the
radiator filler.
Remove the overflow tube clamp and
disconnect the overflow tube.

Loosen the hose band and disconnect the
upper hose and lower hose from the
radiator.

Air Vent Tube

Lower Hose
Upper Hose

Overflow Tube

12. COOLING SYSTEM

12-6

GRAND DINK 125/ 15 0

Disconnect the thermostatic switch wire
coupler.
Disconnect the fan motor wire coupler.

Remove the two bolts and one nut on the
radiator.

RADIATOR DISASSEMBLY

Remove the four bolts and then remove the
fan/shroud from the radiator.

Fan/Shroud

Radiator

Bolts

Thermostatic Switch Wire

Fan Motor Wire Coupler

Bolts

Thermostatic Switch

Nut

12. COOLING SYSTEM

12-7

GRAND DINK 125/ 15 0

Check fan motor by battery.

CHECK THERMOSTATIC SWITCH

When coolant temperature lower then
83~87℃ the thermostatic switch OFF.
When coolant temperature over 88~92℃
the thermostatic switch ON.

Install the fan shroud on the radiator with
the four bolts.

Radiator

Thermostatic Switch

Bolts

Fan Motor

Battery

Fan Shroud

12. COOLING SYSTEM

12-8

GRAND DINK 125/ 15 0

RADIATOR INSTALLATION

Install the radiator on the radiator bracket
with the two bolts and one nut.

Connect the upper and lower hoses and
secure them with hose bands.
Connect the thermostatic switch wire and
fan motor wire couplers.

Connect the overflow tube and secure with
the tube clamp.
Connect the vent tube to the radiator filler.
Fill the radiator with coolant. (!3-9)
After installation, check for coolant leaks.

.

Air Vent Tube

Radiator

Upper Hose

Overflow Tube

Lower Hose

Bolts

Thermostatic Switch
Wire

Nut

12. COOLING SYSTEM

12-9

GRAND DINK 125/ 15 0

Install the front upper cover.

WATER PUMP

MECHANICAL SEAL (WATER SEAL)
INSPECTION

Inspect the

telltale hole for signs of

mechanical seal coolant leakage.
If the mechanical seal is leaking, remove the

right crankcase cover and replace the
mechanical seal.

WATER PUMP/IMPELLER REMOVAL

Remove the coolant inlet hose and outlet
hose.

Right Crankcase Cover

Telltale Hole

Water Pump

Outlet Hose

Inlet Hose

12. COOLING SYSTEM

12-10

GRAND DINK 125/ 15 0

Remove the four bolts and the water pump
cover, gasket and 2 dowel pins.

Remove the water pump impeller.

Inspect the mechanical (water) seal and seal
washer for wear or damage.

Impeller (Left Hand Threads)

Mechanical Seal

Seal Washer (Porcelain)

Water Pump Cover

Bolts

The impeller has left hand threads.

＊

The mechanical seal and seal washer
must be replace as a set.

＊

Impeller

12. COOLING SYSTEM

12-11

GRAND DINK 125/ 15 0

WATER PUMP SHAFT REMOVAL

Disconnect the water hose from the right
crankcase cover.
Remove the 3 bolts attaching the water
pump assembly.
Remove the water pump assembly, gasket
and dowel pins.

Remove the water pump bearing snap ring
from the water pump assembly.
Remove the water pump shaft and shaft
inner bearing.

Remove the water pump shaft outer
bearing.

Inner Bearing

Snap Ring

Water Pump Assembly

Bolts

Inner Bearing

Water Pump Assembly

Water Pump Shaft

Water Pump Shaft

12. COOLING SYSTEM

12-12

GRAND DINK 125/ 15 0

Water Pump Assembly

MECHANICAL SEAL REPLACEMENT

Drive the mechanical seal out of the water
pump assembly from the inside.

Drive in a new mechanical seal using a
mechanical seal driver.

WATER PUMP SHAFT INS TALLATION

Drive a new water pump shaft

outer bearing
into the water pump assembly from the
inside.

Mechanical Seal (Water Seal)

Mechanical Seal Driver

Water Pump Assembly

Apply sealant to the right crankcase
cover fitting surface of a new mechanical
seal and then drive in the mechanical seal.

＊

Outer Bearing

12. COOLING SYSTEM

12-13

GRAND DINK 125/ 15 0

Install the water pump shaft and shaft inner
bearing into the waster pump assembly.
Install the snap ring to secure the inner
bearing properly.

Install the dowel pins and a new gasket and
then install the water pump assembly to the
right crankcase cover.
Tighten the 3 bolts to secure the water
pump assembly.

WATER PUMP/IMPELLER
INSTALLATION

When the mechanical seal is replaced, a new
seal washer must be installed to the
impeller.

Inner Bearing

Snap Ring

Water Pump Shaft

Bolts

Water Pump Assembly

When installing the water pump
assembly, aligning the groove on the
water pump shaft with the tab on the oil
pump shaft.

＊

Mechanical Seal

Seal Washer (Porcelain)

Impeller

12. COOLING SYSTEM

12-14

GRAND DINK 125/ 15 0

Install the impeller onto the water pump
shaft.

Torque: 9.8_ 13.7N-m

Install the two dowel pins and a new
gasket.

Install the water pump cover and tighten
the 4 bolts.
Torque: 7.8_ 11.8N-m

Impeller (Left Hand Threads)
Dowel Pins

Water Pump Cover

Bolt

The impeller has left hand threads.

＊

Gasket

12. COOLING SYSTEM

12-15

GRAND DINK 125/ 15 0

THERMOSENSOR

THERMOSENSOR REMOVAL

Remove the seat, met-in box and center
cover.
Drain the coolant.
Disconnect the thermosensor wire.
Remove the thermosensor.

THERMOSENSOR INSPECTION

Suspend the thermosensor in a pan of water
over a burner and measure the resistance
through the sensor as the water heats up.

Temperature(
℃ )

5080100

120

Resistance(W)

1545227

16

THERMOSENSOR INSTALLATION

Apply 3-BOND No. 1212 sealant or
equivalent to the thermosensor threads and
install it into the thermostat housing.
Connect the thermosensor wire.
Fill the radiator with coolant. (!3-9)
Install the center cover, met-in box and seat.
(!2-3)

Be sure to bleed air from the cooling
system.

＊

Thermosensor

Thermosensor Wire

Thermosensor

Thermosensor Wire

Thermosensor

Thermometer

12. COOLING SYSTEM

12-16

GRAND DINK 125/ 15 0

THERMOSTAT

THERMOSTAT REMOVAL

Remove the seat, met-in box and center
cover.
Drain the coolant.
Disconnect the thermosensor wire from the
thermosensor.
Disconnect the water hose from the
thermostat housing.
Disconnect the air vent tube from the
thermostat housing.
Remove the mounting bolt and the
thermostat housing from the cylinder head.

Remove the two bolts and separate the
thermostat housing halves.

Remove the thermostat from the thermostat
housing.

Thermostat Housing

Thermostat

Bolts

Thermostat

Water Hose

Air Vent Tube

Bolt

12. COOLING SYSTEM

12-17

GRAND DINK 125/ 15 0

THERMOSTAT INSPECTION

Suspend the thermostat in a pan of water
over a burner and gradually raise the water
temperature to check its operation.

Technical Data

Begins to open

80±2℃

Full-open

90℃

Valve lift

3.5_ 4.5mm

THERMOSTAT INSTALLATION

The installation sequence is the reverse of
removal.

Fill the cooling system with the specified
coolant. (!3-9)

• Do not let the thermostat touch the pan

as it will give a false reading.

• Replace the thermostat if the valve

stays open at room temperature.

•Test the thermostat after it is opened

for about 5 minutes and holds the
temperature at 70℃ .

＊

O-ring

Thermostat Housing

Thermostat Housing

Replace the O-ring with a new one and
apply grease to it.

＊

Thermostat

Thermometer