Coolant Thermostat (008-013)
B3.9 and B5.9 Series Engines
Section 8 - Cooling System - Group 08
Clean the mating surfaces.
NOTE: Do not let any debris fall into the thermostat cavity
when cleaning the gasket surfaces.
Inspect for Reuse (008-013-007)
Inspect the thermostat for obvious damage such as ob-
structions caused by debris, broken springs, or stuck or
missing vent pins.
Make sure the thermostat is clean and free from corrosion.
Suspend the thermostat and a 100C [212F] thermometer
in a container of well-mixed water.
NOTE: Do not allow the thermostat or thermometer to
touch the side of the container.
Heat the water slowly so the wax element in the thermostat
has sufficient time to react to the rising water temperature.
Check the thermostat as follows:
Starts to open within 1C [34F] of 83C [181F].
Fully open within 1C [34F] of 95C [203F].
A full-open clearance between the thermostat flow valve
Flow Valve and Flange Clearance