1. Park the vehicle on a level surface and turn off the engine. Allow it to cool down completely.
2. Disconnect the negative terminal of the battery to avoid any electrical mishaps.
3. Locate the water pump on the engine. In most Trailblazer models, the water pump is attached to the front of the engine block, below the thermostat housing.
4. Follow the upper radiator hose to where it connects to the engine. The water pump is usually situated nearby. It's a cylindrical-shaped component with a small pulley attached to it.
5. Remove the serpentine belt. To do this, you might need a serpentine belt wrench or a special tool designed to loosen tension on the belt. Be careful not to drop the belt into the engine compartment.
6. Now you need to remove the bolts holding the water pump in place. These bolts can usually be accessed with a standard wrench or socket set.
7. Once the bolts are removed, you should be able to pry the water pump off the engine block. This might require some gentle maneuvering, as the water pump may be stuck to the surface with old gasket material.
8. Clean the mating surface of the engine block thoroughly to remove any old gasket residue or dirt. This will ensure a good seal between the new water pump and the engine.
9. Apply a thin layer of sealant or gasket maker to the new water pump's gasket. Make sure to follow the manufacturer's instructions for the sealant.
10. Carefully position the new water pump onto the engine block and secure it with the bolts. Tighten the bolts in a criss-cross pattern to evenly distribute the pressure.
11. Reinstall the serpentine belt and tensioner.
12. Refill the cooling system with a mixture of coolant and water according to the recommended ratio specified in the vehicle's owner's manual.
13. Reconnect the negative terminal of the battery.
14. Start the engine and let it run for a few minutes. Observe for any signs of leaks or abnormal engine behavior.
15. Check the coolant level again after the engine has cooled down and top up if necessary.
Note: If you're not comfortable performing these steps, it's best to have the water pump replacement done by a qualified mechanic to avoid any potential risks.
