The transmission lines on a Chevy Blazer connect the transmission to the radiator. As the fluid runs through the engine it heats up. Then it runs through the transmission lines to the radiator to be cooled down so it can cycle through the engine once again. When the transmission lines have a leak, the proper amount of fluid can't be circulated through the engine, and this leads to grinding gears and engine damage. You will need to change the transmission lines, a job that should take about an hour.
Raise the front of the Blazer with a jack and lower it onto a pair of jack stands. Slide underneath the Blazer to locate the transmission drain pan. This is a large metal tank surrounded by eight bolts. Place a collection pan beneath the transmission drain pan.
Remove the drain plug bolt in the center of the drain pan with the 1/2-inch socket wrench. Wait 10 to 15 minutes for the fluid to drain completely. Replace the drain bolt.
Pop the hood of the Blazer and locate the two wide, vinyl transmission lines that run from the side of the transmission to the bottom of the radiator. Remove the lines with the flare-nut wrench. Place the open end of the wrench on the hose and slide it up to the nut that connects the hose to the transmission or the radiator. Twist it to loosen the nut and then pull it out. Repeat for each line. Fasten the new lines between the transmission and the radiator.
Lower the car from the jack stands. Locate the transmission dipstick in the top part of the engine cavity above the drain pan. Pull it out and place a funnel in the tube. Pour in 3 quarts of transmission fluid. Replace the dipstick and close the hood.
