check coolant level light stsys on

Remove the air cleaner and duct assembly. See Fig. 10. Drain the coolant until the coolant level is below the thermostat. See COOLING SYSTEM BLEEDING.
Remove the crossover exhaust pipe. See Fig. 11. Remove the radiator hose from the thermostat housing.
Remove the thermostat housing bolts and clean any sealer from the bolt threads. See Fig. 12. Remove the thermostat housing and gasket.
Remove the thermostat. Inspect and clean the mating surfaces.
Install the thermostat housing and gasket. Install RTV sealer (GM P/N 1052366) to the thermostat housing bolt threads. Install the thermostat housing bolts. See TORQUE SPECIFICATIONS.
To complete installation, reverse removal procedure. Fill the cooling system. Inspect the cooling system for leaks. Repair as necessary.