Q: How do you change the fluid and Transmission Pan on Buick Century?
A: To change the fluid, ensure the engine and transmission are at normal operating temperature, and if the vehicle is raised, keep the transmission level. Begin by safely supporting the vehicle on jackstands. For some models, removing the transmission support crossmember may be necessary to access all pan bolts, so support the transmission with a jack beforehand and be cautious of hot fluid. Place a large pan underneath to catch the fluid, loosen all pan screws, and drain the fluid by pulling down one corner, avoiding prying with a screwdriver to prevent damage. After draining, remove the pan screws and clean the pan with solvent, ensuring it is air dried thoroughly and free of lint. A small amount of metal shavings is normal, but excessive amounts indicate potential transmission damage. Next, remove the filter or strainer retaining bolt, clean the reusable strainer if applicable, and replace filters as needed. Install the new filter or cleaned strainer with a new gasket, tightening screws to specified torque. Reattach the pan with a new gasket, tightening bolts evenly, and replace the crossmember if it was removed. Lower the vehicle and add DEXRON®II fluid through the dipstick tube. Start the engine, let it idle without racing, shift through each lever position while holding the brakes, and check the fluid level in PARK, ensuring it is between the two dimples on the dipstick. After driving to warm up the transmission, check the fluid level again, ensuring it reaches the FULL mark, and drain any excess to prevent aeration and potential damage. Before making any diesel engine linkage adjustments, check and adjust the injection timing as necessary, since engine performance impacts transmission shifting characteristics, and perform these adjustments together. The vacuum valve adjustment for THM-350s on 1979 and later models requires special tools.