Cooling System; Coolant Flow; Expansion Tank; Coolant Temperature Measuring - Rotax 915 i A SERIES Operator's Manual

7.2) Cooling system

System Overview

Coolant flow

Expansion tank

Coolant tempera-
ture measuring
1
3
5
Effectivity: 915 i A Series
Edition 0 / Rev. 0
The cooling system of the engine 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. Since the standard location of the radiator is below engine
level, the expansion tank located on the top of the engine allows
for coolant expansion.
From the expansion tank the coolant is sucked back to the
water pump. In common installations the coolant passes a radi-
ator in between. Additionally the expansion tank is closed by a
pressure cap (with excess pressure valve and return valve). At
temperature rise of the coolant the excess pressure valve
opens and the coolant will escape via hose at atmospheric
pressure. In common installation this hose is connected to an
overflow bottle. This overflow bottle allows that, when the en-
gine is cooling down, the coolant will be sucked back into the
cooling circuit.
The coolant temperature sensor is located on cylinder head 4.
Figure 4: Cooling system (symbolic)
Expansion tank
Pressure cap
Level glass
BRP-Rotax
2 Radiator
4 Overflow bottle
December 01 2017
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