Cooling System Of Engine; Expansions Tank; Coolant Temperature Measuring - Rotax 912 ULS 3 Operator's Manual

7.1) Cooling system of the engine
General note
Cooling
Coolant
Expansion tank
Coolant tempera-
ture measuring
Effectivity: 912 Serie
OM Edition 2 / Rev. 0
See Fig. 1.
The cooling system of the ROTAX 912 is designed for liquid coo-
ling of the cylinder heads and ram-air cooling of the cylinders. The
cooling system of the cylinder heads is a closed circuit with an ex-
pansion tank.
The coolant flow is forced by a water pump, driven from the cams-
haft, from the radiator to the cylinder heads. From the top of the
cylinder heads the coolant passes on to the expansion tank (1).
Since the standard location of the radiator (2) is below engine le-
vel, the expansion tank located on top of the engine allows for
coolant expansion.
The expansion tank is closed by a pressure cap (3) (with excess
pressure valve and return valve). At temperature rise of the
coolant the excess pressure valve opens and the coolant will flow
via a hose at atmospheric pressure to the transparent overflow
bottle (4). When cooling down, the coolant will be sucked back into
the cooling circuit.
Readings are taken on measuring point of the hottest cylinder
head, depending on engine installation.
NOTE: The temperature sensors are located in cylinder
head 2 and 3.
BRP-Powertrain page 7-2
April 01/2010