The water pump keeps the engine alive. Circulating coolant goes all around the cylinders of the engine and takes away heat, which is expelled from the engine compartment through the radiator.
Drain the water or coolant into the drain pan by removing the drain plug on the radiator with the ratchet or open end wrench. You may have to remove the lower radiator hose also. If the coolant is dirty or over two years old, take it to an environmentally safe disposal area. Replace the plug and the lower radiator hose.
Remove the main belt by applying opposing force to the belt tensioner.
Take out the water pump pulley bolts with a wrench. If the bolts stick, use a lubricant.
Take out the pulley.
Take out the water pump bolts. Remove the water pump and the old gasket.
Clean the gasket surfaces with the gasket scraper.
Install the new gasket following instructions from the manufacturer. Some gaskets may require a sealing gel or adhesive.
Put the new water pump in place carefully so the gasket isn't damaged.
Finger-tighten the main bolts. Tighten the bolts in two stages according to the torque instructions included with the water pump.
Install the main drive belt. Apply the same force as before to loosen the belt tensioner then move the belt into position.
Replace the coolant and check for leaking coolant.