Here's a general outline of the process. This is NOT a complete, step-by-step guide and should not be substituted for a proper repair manual specific to your vehicle. Consult a repair manual for your specific year and model Trailblazer for detailed instructions and torque specifications.
Before You Begin:
* Safety First: Wear safety glasses, gloves, and old clothes. Transmission fluid is messy and can damage your skin and clothes.
* Gather Supplies: You'll need new cooler lines (get the correct length and fittings!), wrenches (metric sockets are likely needed), a transmission fluid drain pan, new transmission fluid (consult your owner's manual for the correct type and amount), rags, jack stands, jack, and possibly a helper.
* Vehicle Prep: Park on a level surface, engage the parking brake, and chock the wheels.
General Steps (Consult your repair manual for specifics):
1. Locate the Cooler Lines: Identify the transmission cooler lines. They usually run from the transmission to the radiator. They may be attached with clamps or flare nuts.
2. Drain the Transmission Fluid: Locate the transmission fluid drain pan. Carefully drain the transmission fluid into the pan. This step will significantly reduce the amount of fluid spilled during the line replacement.
3. Disconnect the Cooler Lines: Carefully disconnect the cooler lines from the transmission and the radiator. Use the appropriate wrenches and be prepared for some fluid spillage, even after draining. Pay close attention to how the lines are routed.
4. Remove the Old Lines: Carefully remove the old lines. Take note of their routing and any clamps or brackets used to secure them.
5. Install the New Lines: Install the new cooler lines, replicating the routing of the old ones. Secure them with appropriate clamps or brackets. Make sure the lines are properly seated.
6. Reconnect the Cooler Lines: Carefully reconnect the cooler lines to the transmission and the radiator. Tighten the connections securely but avoid over-tightening, which could damage the lines or fittings.
7. Refill the Transmission: Refill the transmission with the correct type and amount of transmission fluid. Consult your owner's manual or a repair manual for the proper procedure. This often involves adding fluid and then checking the fluid level with the engine running.
8. Check for Leaks: Check all connections for leaks. Start the engine and let it idle for a few minutes, then check for leaks again.
9. Dispose of Used Fluid Properly: Properly dispose of the used transmission fluid according to your local regulations. Transmission fluid is harmful to the environment.
Important Considerations:
* Transmission Fluid Type: Use only the transmission fluid specified in your owner's manual. Using the wrong fluid can severely damage your transmission.
* Torque Specifications: Use the correct torque specifications when tightening the fittings. Over-tightening can damage the lines or fittings, while under-tightening can lead to leaks.
* Repair Manual: A repair manual specific to your 2003 Chevrolet Trailblazer is highly recommended. It will provide detailed instructions, diagrams, and torque specifications.
Again, this is a general overview. Attempting this repair without the proper knowledge and tools can lead to significant damage to your vehicle. If you are not comfortable performing this repair yourself, it's best to take your vehicle to a qualified mechanic.
