Reliant Rebel 700 1967 Workshop Manual page 23

The thermostat should start to open at 86-89°C (187-193°F) and be
fully open when the water reaches boiling point.
If the thermostat does not function correctly replace it with a new
one. Thermostats cannot be adjusted or repaired.
Temperature gauge and sender unit
The temperature gauge reading depends upon the variation in
resistance of a thermistor. Needle fluctuation is reduced by the use of
silicone in the pointer bearing.
Cooling system specification
Cooling system
Capacity including heater
Radiator
Cap pressure
Thermostat
Type
Starts to open
Fully open
Opening distance
Fan
Fan Diameter (4 blade)
Belt tension
Water pump
Type
Pulley ratio
3.98 litres (7 pints) – 700cc
3.41 litres (6 pints) – 750cc
0.281kg/cm² (4 lb/in²)
Wax
86-89°C (187-193°F)
103°C (218°F)
7.11 mm (0.28 in)
254 mm (10 in)
13 mm (½ in) total free movement
Centrifugal
1.172:1
If faulty readings are suspected check the unit as follows:
With the ignition on, disconnect the wire from the sender unit
(located on the side of the thermostat housing). The gauge should
read "cold". Now earth the sender wire to the engine and the needle
should move to "hot". This proves the gauge is correctly working so
would indicate that any incorrect reading will be due to a faulty
sender unit, which will need replacement. A fault in the gauge will
require replacement of the unit.
Anti-freeze quantities
Volume Fluid
In water Down to
% °C (°F)
10 -4 (+25)
15 -7 (+20)
20 -9 (+15)
25 -13 (+9)
30 -16 (+3)
40 -25 (-13)
50 -37 (-34)
Page 23
Solidifies Amount of
At Anti-freeze
°C (°F) required
0.37 litres
-8 (+17) (0.65 pints)
0.55 litres
-14 (+17) (0.96 pints)
0.74 litres
-19 (-3) (1.3 pints)
0.92 litres
-29 (-20) (1.62 pints)
1.11 litres
-39 (-38) (1.94 pints)
1.48 litres
-48 (-54) (2.6 pints)
1.84 litres
-58 (-72) (3.25 pints)
Specific
gravity
1.016
1.026
1.034
1.042
1.050
1.065
1.080