Replace or repair transmission cooler lines that route automatic transmission fluid between the transmission and the radiator-mounted cooler.

Warnings

Tools required

Parts

• Transmission cooler line set (inlet and outlet) × 1 — Use OEM specification
• Transmission cooler line clips × 4 — Replace if damaged
• Transmission cooler line seals/washers × 4 — Use OEM specification

Fluids

• Toyota WS ATF — 2 qt

Preparation

1. Park vehicle on level surface and apply parking brake
2. Place wheel chocks behind rear wheels
3. Ensure transmission is cool to the touch
4. Raise front of vehicle and support securely on jack stands at manufacturer-specified lift points
5. Remove front plastic engine under cover using 10mm socket (typically 8-10 fasteners)
6. Place drain pan under transmission cooler line connections at radiator

Procedure

1. 1

   Document cooler line routing
   Inspect and photograph the routing of both transmission cooler lines from the transmission to the radiator. Note the position of all clips and brackets. The upper line is typically the return line from the cooler, and the lower line is the feed line to the cooler.
2. 2

   Disconnect cooler lines at radiator
   Using a 14mm flare nut wrench, carefully loosen the cooler line fittings at the radiator. Turn counterclockwise slowly to avoid rounding the fittings. Allow ATF to drain into the pan. Once loose, remove fittings completely by hand and cap or plug the radiator ports to prevent contamination.
3. 3

   Remove radiator-side line support brackets
   Remove any clips or brackets securing the cooler lines near the radiator using a 10mm socket. These are typically plastic clips that snap into place or small bolts. Keep all hardware organized for reinstallation.
4. 4

   Disconnect cooler lines at transmission
   Locate the cooler line connections on the driver's side of the transmission. Using a 14mm flare nut wrench, loosen both fittings at the transmission case. Allow remaining ATF to drain into the pan positioned below. Some fluid loss (1-2 quarts) is normal.
5. 5

   Remove line mounting clips along chassis
   Trace the cooler lines from transmission to radiator and remove all mounting clips and brackets securing the lines to the subframe, body, and chassis. These may be plastic push-clips or 10mm bolts. The lines typically run along the driver's side of the vehicle.
6. 6

   Remove old cooler lines
   Carefully pull the old cooler lines free from the vehicle. Check for any additional clips or tie points that may have been missed. Inspect the old lines for the cause of failure (corrosion, physical damage, connection leaks) to prevent recurrence.
7. 7

   Prepare new cooler lines
   Unpack new cooler lines and verify they match the old lines in length and fitting configuration. Install new sealing washers or O-rings on all four connection points (two at transmission, two at radiator). Ensure fittings are clean and free of debris.
8. 8

   Route and install new cooler lines
   Route the new cooler lines along the same path as the originals, ensuring they do not contact hot exhaust components or moving parts. Install mounting clips and brackets finger-tight initially. Verify clearance to suspension components and steering linkage through full range of motion.
9. 9

   Connect lines at transmission
   Thread the cooler line fittings into the transmission case by hand to prevent cross-threading. Once hand-tight, use a 14mm flare nut wrench to snug the fittings. Torque to 25-30 ft-lbs (do not overtighten as this can damage aluminum threads in the transmission case).
10. 10

    Connect lines at radiator
    Thread the cooler line fittings into the radiator connections by hand. Ensure new sealing washers are properly seated. Once hand-tight, use a 14mm flare nut wrench to snug the fittings. Torque to 25-30 ft-lbs.
11. 11

    Secure all mounting points
    Tighten all mounting clips and brackets along the cooler line routing. Ensure lines are secure but not over-tightened, which could cause stress fractures. Verify adequate clearance from moving and hot components.
12. 12

    Refill transmission fluid
    Locate the transmission dipstick on the driver's side of the engine bay. Using a funnel, add approximately 2 quarts of Toyota WS ATF to replace fluid lost during the procedure. Start with less and check level rather than overfilling.
13. 13

    Check fluid level and inspect for leaks
    Start the engine and let it idle. Shift through all gear positions (P-R-N-D-L), pausing 2 seconds in each. Return to Park. With engine running and transmission at operating temperature (usually 10 minutes of idling), check fluid level on dipstick. Fluid should be in the HOT range. Add fluid as needed in small increments.

Reassembly

1. Reinstall front engine under cover using 10mm fasteners
2. Lower vehicle from jack stands
3. Double-check all connection points for tightness and proper routing
4. Clean up any spilled ATF from chassis and subframe

Verification

• With engine running and transmission at normal operating temperature, verify fluid level is in the HOT range on dipstick
• Inspect all four connection points (two at transmission, two at radiator) for any signs of leakage
• Test drive vehicle for 10-15 minutes, including highway speeds to ensure transmission reaches full operating temperature
• Re-inspect all connections for leaks after test drive
• Recheck transmission fluid level after test drive and top off if necessary
• Monitor for leaks over the next few days, checking under the vehicle before first start each morning

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