How to Install Transmission Cooler Lines


A transmission's components spin and create heat during operation. If enough heat is generated, the transmission will fail. To cool the transmission and the fluid within it, two transmission cooler lines connect to a cooling reservoir at the bottom of the radiator. Unfortunately, because the cooler lines are made of brass, they can easily become damaged and must be replaced.

Things You'll Need

  • Floor jack
  • Jack stands
  • Drip pan
  • Flare-nut wrench
  • New cooler line
  • Transmission fluid
  • Allow at least two hours for the transmission to cool if the vehicle has been operated, then lift it with a floor jack and place jack stands under the vehicle's frame.

  • Place a drip pan under the transmission.

  • Disconnect the two cooler lines from the side of the transmission. The cooler lines are on the passenger side of the transmission on most vehicles. Both lines are made of brass. There is an integral nut at the end of each line where it enters the transmission. Twist both nuts in a counterclockwise direction with a flare-nut wrench. Do not use a standard wrench, as it may bend the soft brass lines. Pull the lines out of the transmission and allow any fluid to drain into the drip pan.

  • Disconnect the two transmission cooler lines from the bottom of the radiator. Place a drip pan underneath the lines to capture any fluid which escapes from the lines, then loosen the integral nut on the end of each line with a flare-nut wrench and pull the lines away from the radiator.

  • Pull the transmission cooler lines out from underneath the vehicle.

  • Feed one end of each new cooler line from the front of the vehicle toward the transmission.

  • Place the tip of each cooler line against its fitting on the side of the transmission, then tighten the line's integral nut with a flare-nut wrench.

  • Place the tip of the opposite end of each cooler line against its fitting on the bottom of the radiator, then tighten the line's integral nut with a flare-nut wrench.

  • Raise the vehicle with a jack, remove the jack stands from underneath the vehicle's frame and lower the vehicle to the ground.

  • Add transmission fluid to complete the replacement. Turn the engine on, depress the brake pedal and shift through the gears several times. Turn the engine off, then withdraw the transmission's dipstick tube. The fluid level must be at or just below the "FULL" mark on the tip of the dipstick. Pour transmission fluid into the dipstick tube, periodically checking the fluid level with the dipstick until the "FULL" mark is reached.

Related Searches


  • Motor's Auto Repair Manual; Ralph Ritchen; 1968
  • Automatic Transmission Diagnosis and Repair; Chilton; 1998
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