Tools You'll Need:
* New thermostat (appropriate for your Blazer's engine – check your manual)
* New thermostat gasket (often included with the thermostat)
* Socket wrench set (various sizes)
* Wrenches (various sizes)
* Pliers
* Drain pan
* Antifreeze (50/50 mix of coolant and distilled water)
* Funnel
* Rags or shop towels
* Jack and jack stands (highly recommended)
* Gloves
Steps:
1. Safety First: Disconnect the negative battery cable to prevent electrical shorts. Let the engine cool completely before starting. Working on a hot engine can lead to serious burns.
2. Drain Coolant: Locate the drain plug on the radiator (usually at the bottom). Place your drain pan underneath and carefully open the drain plug to let the coolant drain. This is messy, so be prepared.
3. Access the Thermostat Housing: The location of the thermostat housing varies slightly depending on the engine (4.3L V6 or 5.7L V8). You'll likely need to remove some components for access. This may involve removing some hoses, air intake components, or other parts. Refer to your repair manual for the precise location and steps for your specific engine.
4. Remove the Thermostat Housing: Once you have access, carefully remove the bolts securing the thermostat housing. Have a rag handy to catch any remaining coolant.
5. Remove the Old Thermostat: The thermostat should be visible inside the housing. Carefully remove the old thermostat and the old gasket. Clean the housing thoroughly of any old gasket material.
6. Install the New Thermostat and Gasket: Install the new gasket into the thermostat housing. Then, carefully install the new thermostat, ensuring it's correctly seated.
7. Reinstall the Thermostat Housing: Carefully reinstall the thermostat housing and tighten the bolts to the manufacturer's specified torque (check your repair manual).
8. Reconnect Hoses: Reattach any hoses that were removed to gain access to the thermostat housing.
9. Refill the Cooling System: Slowly add the 50/50 mix of antifreeze and distilled water to the radiator until it's full. Bleed the air from the system by squeezing the upper radiator hose and opening the radiator cap (carefully and slowly; be aware that the system will be under pressure). Refer to your repair manual for the proper bleeding procedure.
10. Check for Leaks: Start the engine and let it run for a few minutes. Carefully check for any leaks around the thermostat housing and hoses.
11. Reconnect Battery Cable: Once you're satisfied there are no leaks, reconnect the negative battery cable.
Important Considerations:
* Repair Manual: A repair manual specific to your 1999 Chevrolet Blazer is crucial. It will provide detailed diagrams, torque specifications, and specific instructions.
* Engine Type: The procedure varies slightly depending on whether you have the 4.3L V6 or the 5.7L V8 engine.
* Coolant Type: Use the correct type of coolant for your Blazer. Mixing different types of coolant can cause problems.
This is a simplified overview. Improper installation can lead to overheating, engine damage, and potentially serious injury. If you are uncomfortable performing this task, take your vehicle to a qualified mechanic.
