Hardening, shrinkage, or damage of both gaskets and O-rings after disassembly can reduce sealing performance.
Remove old gaskets and clean the sealing surfaces thoroughly so that no gasket material or other material remains.
Install the new gaskets and replace the used O-rings when re-assembling.

Force
Liquid Gasket, Non-permanent Locking AgentThermostat Inspection
Remove the thermostat (see Thermostat Removal).
Inspect the thermostat valve [A] at room temperature.
If the valve is open, replace the thermostat with a new
one.
To check valve opening temperature, suspend the thermostat
[A] in a container of water and raise the temperature
of ...
Idle Speed Control Valve Actuator Resistance Inspection
Turn the ignition switch to OFF.
Remove the air cleaner housing (see Air Cleaner Housing
Removal in the Fuel System (DFI) chapter).
Disconnect the idle speed control valve actuator connector
[A].
Connect a digital meter to the idle speed control valve
actuator connector [A]
...
Radiator Inspection
Remove the radiator (see Radiator and Radiator Fan Removal).
Check the radiator core.
If there are obstructions to air flow, remove them.
If the corrugated fins [A] are deformed, carefully
straighten them.
If the air passages of the radiator core are blocked more
than 20% by unremovable ...