Radiator Pressure Cap - Check; Coolant Reservoir - Removal And Installation - Yamaha TDM850 User Manual

3*2 Cooling system
1 General information
The cooling system uses a water/antifreeze
coolant to carry away excess energy in the form
of heat. The cylinders are surrounded by a water
jacket from which the heated coolant is circulated
by thermo-syphonic action in conjunction with a
water pump, driven by the front balancer shaft.
The hot coolant passes upwards
thermostat and through to the radiator. The
coolant then flows across the radiator core,
where it is cooled by the passing air, to the water
pump and back to the engine where the cycle is
repeated.
A thermostat is fitted in the system to prevent
the coolant flowing through the radiator when the
engine is cold, therefore accelerating the speed
at which the engine reaches normal operating
temperature. A coolant temperature sensor
mounted in the thermostat housing transmits to
the temperature gauge on the instrument panel.
A thermostatically-controlled cooling fan is also
fitted to aid cooling in extreme conditions. The
fan switch is mounted in the thermostat housing.
3.2a Breather hose (A), mounting bolts (B) -
TDM models
3.2b Breather hose (A), radiator overflow hose (B), mounting
screws (C) - TRX models
The complete cooling system is partially sealed
and pressurised, the pressure being controlled by
a valve contained in the spring-loaded radiator
cap. By pressurising the coolant the boiling point
is raised, preventing premature boiling in adverse
conditions. The overflow pipe from the system is
connected to a reservoir into which excess
coolant is expelled
discharged coolant automatically returns to the
radiator when the engine cools.
A
Warning: Do not remove the
pressure cap from the radiator when
to the
the engine is hot. Scalding hot coolant
and steam may be blown out
underpressure, which could cause serious
injury. When the engine has cooled, place a
thick rag, like a towel over the pressure cap;
slowly rotate the cap anti-clockwise to the first
stop. This procedure allows any residual
pressure to escape. When the steam has
stopped escaping, press down on the cap
while turning it anti-clockwise and remove it.
Do not allow antifreeze to come in contact with
your skin or painted surfaces of the
motorcycle. Rinse off any spills immediately
with plenty of water. Antifreeze is highly toxic
if ingested. Never leave antifreeze tying around
in an open container or in puddles on the
floor; children and pets are attracted by its
sweet smell and may drink it. Check with the
local authorities about disposing of used
antifreeze. Many communities will have
collection centres which will see that
antifreeze is disposed of safely. Caution: At all
times use the specified type of antifreeze, and
always mix it with distilled water in the correct
proportion. The antifreeze contains corrosion
inhibitors which are essential to avoid damage
to the cooling system. A lack of these
inhibitors could lead to a build-up of corrosion
which would block the coolant passages,
resulting in overheating and severe engine
damage. Distilled water must be used as
opposed to tap water to avoid a build-up of
scale which would also block the passages.
under pressure. The
1 If problems such as overheating or loss of
coolant occur, check the entire system as
described in Chapter 1. The radiator cap opening
pressure should be checked by a Yamaha dealer
with the special tester required to do the job. If
the cap is defective, renew it.
Coolant reservoir -
removal and installation
Removal
1 On TDM models, remove the seat {see
Chapter 8). On TRX models, remove the seat
and the side covers (see Chapter 8). On XTZ
models remove the left-hand side cover (see
Chapter 8).
2 Release the clamp securing the breather hose
(coming out of the top of the reservoir) and
detach the hose (see illustrations).
3 Place a suitable container underneath the
reservoir, then release the clamp securing the
radiator overflow hose to the base of the
reservoir. Detach the hose and allow the coolant
to drain into the container.
4 Unscrew the reservoir mounting bolts or
screws and remove the reservoir, noting how it
fits (see illustrations 3.2a, b and c).
Installation
5 Installation is the reverse of removal. Make
sure the hoses are correctly installed and
secured with their clamps. On completion
refill the reservoir as described in Chapter 1.
3.2c Breather hose (A), radiator overflow hose (B), mounting
screws (C) - XTZ models
I
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