Here's a general outline. This is NOT a substitute for a detailed repair manual specific to your year and engine (4.3L, 5.7L, etc.). Consult a Haynes or Chilton manual for your exact vehicle. Variations exist depending on engine and transmission configuration.
Tools You'll Likely Need:
* Jack and jack stands: Absolutely essential for safety.
* Wheel chocks: To further secure the vehicle.
* Wrench set (metric): Various sizes, likely including 10mm, 13mm, 15mm and possibly larger.
* Socket set (metric): Matching the wrench sizes.
* Oil filter wrench: For removing the oil filter (convenient while you're in there).
* Drain pan: For catching old oil.
* New oil cooler lines: Get the correct part numbers for your Blazer's engine and transmission.
* New oil filter and oil: Replace these while you have things apart.
* Torque wrench: To tighten connections to the proper specification (crucial to avoid leaks).
* Rags or shop towels: For cleanup.
* Penetrating oil (PB Blaster, etc.): To loosen stubborn fittings.
* Possible need for a line wrench: For difficult-to-reach fittings.
General Procedure (Consult your repair manual for specifics):
1. Preparation: Warm up the engine slightly to thin the oil. Place the drain pan under the oil pan. Remove the oil drain plug and let the oil drain completely. Remove the oil filter.
2. Access: Locate the oil cooler lines. They're usually near the engine block, often connected to the oil filter housing or a separate oil cooler. You'll likely need to work from underneath the vehicle.
3. Disconnection: Apply penetrating oil to the fittings on the oil cooler lines. Carefully loosen the fittings connecting the oil cooler lines to the engine block and oil cooler using the appropriate wrenches. Be prepared for some resistance. Note the orientation and order of any washers or gaskets; replace them with new ones.
4. Line Removal: Carefully remove the old oil cooler lines. Take pictures or make notes to remember their routing and placement.
5. Installation: Install the new oil cooler lines, paying close attention to their routing and ensuring all connections are secure. Tighten the fittings to the manufacturer's specified torque. Do not overtighten.
6. Reconnection: Reconnect the oil filter and drain plug.
7. Refill: Refill the engine with the correct amount and type of oil (check your owner's manual).
8. Check for leaks: Start the engine and let it run for a few minutes. Check for any leaks around the connections. Let the engine cool down and check the oil level again. Top off as needed.
Important Considerations:
* Engine type: The location and access to the oil cooler lines will vary depending on whether you have a 4.3L V6 or a 5.7L V8 engine.
* Transmission type: The location of the lines might also be affected by the transmission type (automatic or manual).
* Torque specifications: Over-tightening can damage the fittings. Use a torque wrench and consult your repair manual for the correct torque specifications.
* Fluid type: Use the correct type and amount of engine oil specified in your owner's manual.
This is a complex repair. If you're not comfortable working on your vehicle, it's best to take it to a qualified mechanic. Improperly installed oil cooler lines can lead to engine damage. Again, a repair manual specific to your 1998 Chevy Blazer is crucial.
