However, if you're determined to do it yourself, here's a general outline. This is NOT a complete, step-by-step guide and may not cover every variation. Always consult a repair manual specific to your year and model Trailblazer for detailed instructions and torque specifications. A Haynes or Chilton manual is a good investment.
Tools You'll Likely Need:
* Repair Manual: Absolutely essential.
* Jack and Jack Stands: Securely support the vehicle.
* Wheel Chocks: For safety.
* Socket Set and Wrenches: Various sizes, including metric.
* Ratchet and Extensions: For reaching tight spots.
* Screwdrivers: Phillips and flathead.
* Pliers: Needle-nose and regular.
* Drain Pan: For coolant.
* New Water Pump: Ensure you get the correct part number for your vehicle.
* New Thermostat (recommended): While you're in there, it's a good idea to replace this as well.
* New Coolant: Use the correct type and amount specified in your owner's manual.
* New Gaskets and Seals: These are crucial to prevent leaks.
* Torque Wrench: To tighten bolts to the proper specifications – essential to prevent damage.
* Clean Rags or Shop Towels: For cleaning and absorbing spills.
General Steps (Consult your repair manual for specifics):
1. Safety First: Disconnect the negative battery terminal. Allow the engine to cool completely before starting.
2. Drain the Coolant: Locate the drain plug at the bottom of the radiator and the engine block. Use the drain pan to collect the coolant.
3. Remove the Fan and Fan Shroud: This typically involves removing several bolts and possibly disconnecting the fan clutch.
4. Remove the Serpentine Belt: Use the correct tool to loosen the tensioner pulley and remove the belt.
5. Remove the Water Pump Pulley: This might involve removing a bolt or nut.
6. Remove Accessory Components (if necessary): Depending on your specific Trailblazer, you may need to remove other components like the alternator or power steering pump to access the water pump.
7. Remove the Water Pump: This usually involves removing several bolts holding the pump to the engine block.
8. Clean the Mounting Surface: Carefully clean the mounting surface of the engine block to ensure a good seal.
9. Install the New Water Pump: Install the new water pump with the new gasket, ensuring it's seated properly. Tighten the bolts to the correct torque specifications (found in your repair manual).
10. Reinstall Components: Carefully reinstall all components removed in reverse order, ensuring all connections are secure.
11. Reinstall the Serpentine Belt: Ensure proper routing of the belt.
12. Reinstall the Fan and Fan Shroud.
13. Refill the Coolant System: Use the correct type and amount of coolant. Bleed the air from the system (consult your repair manual for the procedure).
14. Start the Engine: Let the engine run for a while to check for leaks. Monitor the temperature gauge.
15. Check for Leaks: After the engine has cooled, carefully inspect for any coolant leaks.
Important Considerations:
* Coolant Type: Use the correct type of coolant specified for your Trailblazer. Mixing different types can damage the engine.
* Torque Specifications: Using the wrong torque can strip threads or damage the engine block. Always use a torque wrench and consult your repair manual.
* Gaskets and Seals: Using new gaskets and seals is crucial to prevent leaks.
This is a simplified overview. Refer to a repair manual specific to your 2005 Chevy Trailblazer 4.2L for detailed instructions, diagrams, and torque specifications. If you're unsure about any step, seek professional help. Improper repair can lead to serious engine damage.
