Chevrolet equipped the 1997 model-year Blazers with a hydraulic automatic transmission. Hydraulic transmission fluid is contained by the transmission pan, which forms a sump to collect the fluid as it drains from the transmission. Fluid filtration is provided by a screen-type filter that extends from the pickup port in the transmission body down into the sump. Transmission fluid must be regularly changed to avoid transmission damage and varnish build-up that can affect transmission performance.
Park the Blazer on a level surface. Allow the truck to cool completely.
Lift the front and rear of the vehicle with a jack. Support the vehicle with two sets of jack stands.
Remove the transmission shift cable bracket bolts with a wrench. Pull the shift cable bracket off of the transmission.
Place a catch pan under the transmission pan. Remove the front and side transmission oil pan bolts with a wrench. Loosen the rear pan bolts about four turns with a wrench.
Tap lightly sideways on the transmission pan with a rubber hammer. Use caution to avoid deforming the pan body and the pan mounting flange. Knock the pan loose from the transmission gently, allowing it to drop slightly and drain into the catch pan. Allow the fluid to drain completely.
Remove the remaining bolts by hand and lower the pan away from the transmission. Pour the remaining fluid into the catch pan.
Pull the transmission filter down and out of the transmission by hand. Ensure that the filter gasket was removed with the filter. Remove the filter gasket from the filter port with a finger or ratchet handle, if necessary.
Scrape the pan gasket from the pan and the pan's mount surface on the transmission with a gasket scraper. Wipe the gasket surfaces and the pan interior with a clean shop rag. Remove any gasket material or residue from the pan.
Apply a layer of Transjel or equivalent to the new filter seal. Insert the seal into the transmission port. Slide the new filter into the port and seal until it bottoms out on the transmission.
Place the new transmission pan gasket onto the pan. Lift the pan into place against the transmission and install the pan bolts. Tighten the pan bolts to 12 foot-pounds with a 3/8-inch torque wrench.
Install the shift cable bracket and bolts onto the transmission. Torque the bolts to 12 ft. lbs. with a 3/8-inch torque wrench.
Raise the vehicle with a jack and remove the jack stands. Lower the vehicle to the ground.
Add Dexron III transmission fluid or equivalent through the transmission dipstick tube to the proper level as indicated by the dipstick. Start the engine and check for leaks around the transmission pan. Recheck the fluid level and add as indicated by the dipstick. Do not overfill the transmission.
