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COOLING SYSTEM
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SERVICE INFORMATION -------------------------------------------- 12- 1
TROUBLESHOOTING ------------------------------------------------- 12- 1
COOLING SYSTEM TESTING --------------------------------------- 12- 3
RADIATOR -------------------------------------------------------------- 12- 4
WATER PUMP ---------------------------------------------------------- 12- 6
THERMOSENSOR ------------------------------------------------------ 12-10
THERMOSTAT---------------------------------------------------------- 12-11

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¢J, 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 1.0_ 1.4kgf-m
Water pump cover bolt 0.8_ 1.2kgf-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

Radiator cap relief pressure
Radiator: 1100±20cc
Reserve tank: 300±20cc
Temp. ¢J
Coolant
concentration
COOLANT MIXTURE (WITH ANTI-RUST AND ANTI-FREEZING EFFECTS)
KYMCO SIGMA Coolant Concentrate
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¢Jlower than the freezing point of the
riding area.

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:
0.75~1.05kg/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.
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.