Before you begin:
* Consult your owner's manual: This is crucial. It will provide specific details for your Suburban's transmission type and may have diagrams.
* Identify your transmission type: This determines the exact filter and procedure. TH400 and TH700R4 are common, but others are possible.
* Gather your supplies: This includes the correct transmission filter for your transmission type, new transmission fluid (the correct type and amount, check your manual), a drain pan, a torque wrench, sockets, wrenches, jack stands, jack, funnel, shop rags, gloves, and possibly a transmission fluid pump.
General Steps (these are general guidelines and may not apply exactly to your Suburban):
1. Safety First: Park on a level surface, engage the parking brake, and chock the wheels. Wear safety glasses and gloves.
2. Vehicle Preparation: Raise the vehicle securely using jack stands. Never work under a vehicle supported only by a jack.
3. Locate the Transmission Pan: The transmission pan is usually located on the bottom of the transmission. It's a relatively large, usually rectangular, metal pan.
4. Drain the Transmission Fluid: Position your drain pan under the transmission pan. Carefully loosen and remove the drain plug. Let the fluid drain completely. This can take a significant amount of time.
5. Remove the Transmission Pan: Once drained, carefully remove the transmission pan bolts. The pan will likely be heavy and contain residual fluid, so support it as you remove the last bolts. Be prepared for a spillage of remaining fluid.
6. Replace the Filter: The filter is usually attached to the transmission pan, either inside or bolted to the pan's bottom. Remove the old filter and install the new one, ensuring it's seated correctly.
7. Clean the Pan: Inspect the transmission pan for any debris or damage. Clean it thoroughly with a suitable solvent and let it dry. Replace the pan gasket (if reusable), or use new gasket material as needed.
8. Reinstall the Transmission Pan: Carefully reinstall the transmission pan, ensuring the gasket is properly seated. Tighten the bolts evenly and to the manufacturer's specified torque (consult your manual or a repair manual).
9. Refill with Transmission Fluid: Carefully refill the transmission with the correct type and amount of transmission fluid. You may need to use a transmission fluid pump to avoid spills. Check the fluid level using the dipstick (your manual will show how). It's important to get the fluid level right; too much or too little can damage the transmission.
10. Lower the Vehicle: Carefully lower the vehicle and check for leaks around the transmission pan.
11. Test Drive: Take the vehicle for a short test drive to check the transmission's performance.
Important Considerations:
* Torque Specifications: Using a torque wrench is vital to avoid over-tightening or under-tightening bolts.
* Transmission Type: The procedure varies slightly depending on your transmission type (TH400, TH700R4, etc.). You must find information specific to your transmission.
* Repair Manual: A Haynes or Chilton repair manual for your 1989 Chevy Suburban 350 is highly recommended. These manuals provide detailed instructions, diagrams, and torque specifications.
* Professional Help: If you're uncomfortable with this level of auto repair, take your Suburban to a qualified mechanic. A poorly executed transmission service can lead to expensive transmission problems.
This is a complex task. Improperly completing it could damage your transmission, costing you significantly more in repairs. Always prioritize safety and consult a professional if you're unsure.
