To perform the replacement of the engine coolant Thermostat housing (LE5), one must take into consideration draining the cooling system utilizing the given drain at the bottom side of the Water Pump for the purpose of engine block coolant drainage. Take off the Water Pump Drain Plug to drain coolant off the engine block and then lower the vehicle. Remove the bracket and disconnect the engine coolant temperature (ECT) sensor and the heated Oxygen Sensor (HO2S) electrical connector clip. Before you remove the radiator outlet hose, you should remove ect sensor and surge tank outlet hose as well as reposition the radiator outlet hose clamp. Next, undo the bolts that hold the Exhaust Heat Shield and take out the heat shield, then reclamp and take off the heater inlet and outlet hose clamps from the Thermostat housing pipes. Before taking the Thermostat housing off, remove the Thermostat housing bolts by twisting the water transfer pipe and pull it off the Water Pump. Removing the Thermostat housing. If needed, remove the water transfer pipe from the Thermostat housing and dispose of the o-ring seals. Undo the Thermostat housing cover bolts and housing cover, the Thermostat if necessary while making sure to clean any debris and thread sealant from the ect sensor and bolt holes if the housing is to be used again. Again for installation, fit a new Thermostat housing o-ring seal to the recess groove, fit the Thermostat if it is required, and bolt the cover to 10 nm (89 lb/ in). Install a new Thermostat housing to engine o-ring seal on Thermostat housing, load the assembly into place, and lubricate the water feed pipe seals with a little coolant. Place new o-ring seals on water feed pipe and put it into the Thermostat housing properly align with the locator tab and seat the o-ring seal press toward the Water Pump, and avoid damaging it. Placed the Thermostat housing against the engine and tighten the housing bolts to 10 nm (89 lb in) and reconnected the heater inlet and outlet hoses to the housing pipes of the Thermostat making sure that the clamps are well in position. Reinstall the Exhaust Heat Shield along with the bolts and tighten them to 23 nm (17 lb ft) and fit the radiator outlet hose to the Thermostat housing and tighten the surge tank to the housing using clamps. Seal the threads of the ect sensor, mount it, and tighten to 20 nm (15 lb ft), then reconnect the ect sensor electrical connector and the ho2s electrical clip connector. Finally, apply sealant gm p/n 12378521 (Canadian P/N 88901148) or equivalent to the Water Pump Drain Plug, install it, and tighten it to 20 nm (15 lb ft). Make sure the vehicle is leveled, check the shut off of the drain valves located on the radiator itself and Water Pump, fill up the cooling system, and check for any leaks to guarantee the fix.