TOMARK, s.r.o.
Airplane Maintenance Manual
Chapter75 Air
Issue: 28.FEB 2017
Page 177
75
Air
75-20
Engine Cooling
The cooling of the ROTAX 912 engine is done by liquid-cooled
cylinder heads and by air-cooled cylinders of the engine. The liquid
cooling of the valve heads is made by a closed circuit with an
expansion and overflow tank.
The cooling system has been filled in the factory by a special
undiluted cooling liquid Sheron Antifreeze G12++.
More information about choosing the right cooling liquid can be
found in the valid issue of the Rotax Service Letter SL-912-016 (refer
to Chapter
The cooling liquid is pumped by the camshaft driven pump from the
radiator to individual cylinder heads. The liquid is then guided from
the cylinder heads into a collector. The expansion tank is closed by a
plug with a pressure and non-return valve. When the liquid heats up
and increases its volume, it opens the overpressure valve and flows
into a transparent overflow tank. The overflow tank is installed in the
middle of the upper firewall. After the liquid is cooled, it is sucked
back into the cooling circuit.
75-20-01 Coolant Thermostat
The thermostat is located at the left side under air box chamber.
Thermostat is connected into coolant hose that feeds the coolant
from expansion tank to radiator.
Thermostat is used to regulate the cooling liquid flow regarding
engine operation temperature.