How to Fix Leaking Auto Transmission Cooler Lines

Written by matt scheer
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How to Fix Leaking Auto Transmission Cooler Lines
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When auto transmission cooler lines are leaking, the best solution is to replace them with new lines. Transmission cooler lines are a set of hoses that run from the transmission to the radiator. They transport hot transmission fluid to the radiator to be cooled down so it can be circulated through the engine again. When cooler lines leak, it leads to insufficient levels of transmission fluid in the car. This can cause major engine damage because of grinding gears and overheating. Fixing these lines requires about an hour and saves on costly repairs.

Skill level:

Things you need

  • 2 Jack stands
  • Socket wrench
  • Collection pan
  • Flare nut wrench
  • Funnel
  • Transmission fluid

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  1. 1

    Park the car on a level surface and raise it up on two jack stands. Wait for about 30 minutes for the engine to cool before you go underneath the vehicle.

  2. 2

    Locate the transmission drain pan beneath the vehicle. This is a large, metal pan surrounded by bolts. Place a collection pan beneath the drain pan. Use the socket wrench to remove the drain bolt in the centre of the drain pan. Allow it to drain for 10 to 15 minutes. Replace the drain bolt.

  3. 3

    Locate the transmission cooler lines that run from the side of the transmission to the bottom of the radiator. The number of lines varies from vehicle to vehicle but typically there are one or two. Use a flare nut wrench to remove the nuts that connect the hoses to both the transmission and the radiator.

  4. 4

    Replace the old lines with new hoses. Use the old nuts to attach the lines to the vehicle.

  5. 5

    Pop the bonnet of the engine and locate the transmission dipstick. Pull it out and place a funnel into the tube. Pour in the designated amount of transmission fluid, as per the owner's manual instructions. Replace the dipstick and close the bonnet.

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