Coolant Temperature, Measure with Closed Cooling System
Install, Connect
Remove lower coolant hose from radiator - collect coolant.
Install temperature gauge in heater hose - note manufacturer's instructions!
Measure
Coolant temperature - operating temperature approx. 80 ° C/176 ° F.
Remove, Disconnect
Temperature gauge.
Install heater hose.
Top up cooling system - see operation "Cooling System, Top Up and Bleed" and "Cooling System, Check for Leaks".
Install, Connect 
Measure 
Remove, Disconnect 