If the thermostat is suspected to be leaking, the following steps can be performed to check for leakage.
The following check must be performed with the thermostat closed for 1 minute of engine operation.
Use an electronic service tool to monitor the coolant temperature. The coolant temperature should be less than
38ยฐC [100ยฐF] to make sure the thermostat does not open during the test.
Disconnect the radiator top hose from the water outlet connection.
Install a hose of the same size on the water outlet connection long enough to reach a remote, dry container
that will be used to collect coolant.
Install and tighten a hose clamp on the outlet connection.
Place the other end of the hose in the dry container.
The coolant temperature should be monitored during this test to determine if the coolant temperature reaches the
nominal opening temperature of the thermostat. See the Measurement section of this procedure for nominal
opening temperature.) If the thermostat opens during this test, the test is invalid and must be repeated.
Operate the engine at rated rpm for 1 minute.
Stop the engine and measure the amount of coolant collected in the container.
The amount of coolant must not be more than 100 cc (3.3 fl oz).
If more than 100 cc [3.3 fl oz) of coolant is collected, the thermostat is leaking and must be replaced.
