Description Of Systems; Cooling System - Rotax OM-912 Operator's Manual

9) Description of systems

9.1)

Cooling system

See fig. 4.
The cooling system of the ROTAX 912 is designed for liquid cooling of the
cylinder heads and ram-air cooling of the cylinders. The cooling system of
the cylinder heads is a closed circuit with an expansion tank.
The coolant flow is forced by a water pump, driven from the camshaft, 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 level, 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 pres-
sure valve opens and the coolant will flow via a hose at atmospheric pres-
sure to the transparent overflow bottle (4). When cooling down, the coolant
will be sucked back into the cooling circuit.
◆ NOTE:
Readings are taken on measuring point of the hottest cylinder head, depen-
ding on engine installation.
Coolant, see Chapter 10.2.1).
2
Kühler / radiator
Effectivity: 912 Serie
OM Edition 1 / Rev. 0
Coolant temperatures are measured by means of tem-
perature probes installed in cylinder heads 2 and 3.
Ausgleichsgefäß / expansion tank
3
1
BRP-Rotax
4
Überlaufgefäß /
overflow bottle
fig. 4
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page 9 - 1
Jan.01/2007