KTM 990 - Manual (Page 72)

A mixture of 50% antifreeze and 50% distilled water is used as the cooling liquid. How ever,
the anti-freeze protection must be at least -25° C (-13° F). Aside from antifreezing protec-
tion, this mixture also provides great corrosion protection which is why it must not be
replaced by pure water.
– For the cooling system, use only high-grade antifreezer (Motorex Anti-Freeze). Using low-
ergrade antifreeze agents, can cause corrosion and coolant foaming.
– More antifreeze must be added if you plan to travel to a region where temperatures are
expected to drop below -25°C (-13°F).
Pressure induced by heating of the cooling liquid in the cooling system is controlled by a
valve in the radiator cap [4]; a water temperature rising up to 125° C (257° F) is admissi-
ble, without fear of problems.
Any excess cooling liquid caused by thermal expansion is conducted to the compensating
tank [5]. It will be sucked back in as soon as the temperature in the cooling system drops.
Checking the cooling liquid level in the compensating tank
Check the level of the cooling liquid when the engine is cold. It should fall between the MIN
and MAX marks on the compensating tank [6].
Add cooling liquid (see above for mixture ratio) if the cooling liquid level drops below the
MIN mark.
If you need to add cooling liquid quite often, the cooling system may leak. If the compen-
sating tank is empty, also check the cooling liquid level in the radiator. Have the cooling
system checked by an authorized KTM workshop.
MAINTENANCE WORK ON CHASSIS AND ENGINE
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