Water Temperature Gauge Test
Thermistor Thermometer Group
Adapter (3/4-16 to 1/4 NPTF)
Reducing Bushing (1/4 NPTF to 1/8 NPTF)
Self-Sealing Probe Adapter with
Check the accuracy of the water temperature gauge if either of
the conditions that follow are found:
The gauge reads normal, but the engine is too hot and a
loss of coolant is found.
The gauge shows that the engine is hot, but no loss of
coolant can be found.
(1) Plug. (2) Water temperature regulator housing.
Remove plug (1) and install the adapter, seal, and the 8T0470
Thermistor Thermometer Group or the 2F7112 Thermometer.
A temperature gauge of known accuracy can also be used to
make this check.
Work carefully around an engine that is running. Engine
parts that are hot, or parts that are moving, can cause
Start the engine and run it until the temperature reaches the
desired range according to the test thermometer. If necessary,
put a cover over part of the radiator or cause a restriction of the
coolant flow. The reading on the gauge for water temperature
should agree with test thermometer within the tolerance range
of the gauge.
Water Temperature Regulator Test
Remove the regulator from the engine.
Heat water in a pan until the temperature is 94°C
(202°F). Move the water around in the pan to make it all
the same temperature.
Hang the regulator in the pan of water. The regulator
must be below the surface of the water and it must be
away from the sides and bottom of the pan.
Keep the water at the correct temperature for 10
After ten minutes, remove the regulator and immediately
measure the distance the regulator has opened. Refer
to the Specifications in this service manual for the
minimum opening length.
If the distance is less than the minimum opening length
from the specifications section in this service manual
then replace the regulator.