Replace or repair transmission cooler lines that run between the transmission and the radiator-mounted cooler to prevent ATF leaks and maintain proper transmission temperature.

Warnings

Tools required

Parts

• Transmission cooler line set × 1 — Use OEM specification
• Transmission drain plug crush washer × 1 — Use OEM specification
• ATF cooler line O-rings × 4 — Use OEM specification

Fluids

• Kia SP-IV-M ATF — 3 qt

Preparation

1. Ensure vehicle has been off and cooling for at least 2 hours to avoid hot fluid burns
2. Park vehicle on level surface and engage parking brake
3. Raise front of vehicle with jack and secure on jack stands rated for vehicle weight
4. Remove front driver side wheel to improve access to transmission cooler lines
5. Remove plastic engine splash shield using 10mm socket (5-7 fasteners)
6. Place large drain pan under transmission and cooler line routing area

Procedure

1. 1

   Drain transmission fluid
   Locate the transmission drain plug on the bottom of the transmission pan. Clean area around drain plug with wire brush. Place drain pan directly beneath plug. Using 24mm socket, slowly loosen and remove drain plug, allowing fluid to drain completely. This typically takes 5-10 minutes. Inspect drain plug magnet for excessive metal debris.
   Torque spec

   Transmission Drain Plug30 Nm (22 lb-ft)
2. 2

   Disconnect cooler lines at radiator
   Locate the two transmission cooler lines where they connect to the lower section of the radiator on the driver side. Using 17mm and 19mm flare nut wrenches, carefully loosen the cooler line fittings at the radiator. Turn counterclockwise slowly to prevent rounding of fittings. Allow residual fluid to drain into pan. Once loose, remove fittings by hand and cap radiator ports with clean shop towels to prevent contamination.
   ⚠Use flare nut wrenches only - standard wrenches will round these fittings. Apply penetrating oil if fittings are corroded.
3. 3

   Trace and support cooler line routing
   Follow both cooler lines from radiator back to transmission, noting routing path, clips, and mounting brackets. Take photos for reference during reinstallation. Remove any clips or fasteners securing lines to chassis or engine components using 10mm socket. The lines run along the front of the transmission.
4. 4

   Disconnect cooler lines at transmission
   Locate where cooler lines connect to the transmission case on the front driver side. Clean the area around fittings thoroughly. Using 19mm flare nut wrench, loosen both line fittings at the transmission. Turn counterclockwise and allow remaining fluid to drain. Once loose, remove fittings by hand and immediately plug transmission ports with clean shop towels or rubber caps to prevent dirt intrusion.
   ⚠Note orientation of supply and return lines - they must be reconnected in the correct positions to ensure proper fluid flow direction.
5. 5

   Remove old cooler lines
   Carefully extract both cooler lines from the vehicle, working them through their routing path. Remove all old mounting clips and brackets. Inspect the old lines to identify leak location or damage. Check radiator cooler ports and transmission ports for cracks or damage.
6. 6

   Prepare and install new cooler lines
   Unpack new cooler lines and verify they match the old lines in length and fitting orientation. Install new O-rings on all four line fittings, lubricating them lightly with clean ATF. Route new lines along the same path as original lines, ensuring no contact with exhaust components, sharp edges, or moving parts. Lines should have slight slack to prevent stress on fittings.
   ⚠Maintain minimum 2-inch clearance between cooler lines and exhaust manifold or downpipe to prevent heat damage.
7. 7

   Connect cooler lines to transmission
   Remove protective caps from transmission cooler ports. Thread supply line fitting (typically upper port) into transmission by hand until fully seated. Tighten with 19mm flare nut wrench to snug, then an additional 1/4 turn. Repeat for return line at lower port. Do not overtighten - fittings seal with O-rings, not thread force.
   ⚠Cross-threading these fittings will damage transmission case. Thread by hand first to ensure proper alignment.
8. 8

   Connect cooler lines to radiator
   Remove protective towels from radiator cooler ports. Thread cooler line fittings into radiator ports by hand until seated. Tighten with appropriate flare nut wrench to snug, then an additional 1/4 turn. Verify both connections are secure but not over-tightened.
9. 9

   Secure cooler lines and reinstall clips
   Install all mounting clips and brackets to secure cooler lines in their proper routing path. Ensure lines are properly supported every 12-18 inches and do not contact moving or hot components. Verify lines have slight flex and are not stretched tight. Double-check clearances at all points.
10. 10

    Install drain plug and refill transmission
    Install new crush washer on drain plug. Thread drain plug into transmission pan by hand, then torque to specification using torque wrench. Locate transmission dipstick tube near firewall on passenger side. Using long-neck funnel, add 3 quarts of Kia SP-IV-M ATF through dipstick tube. Start engine and allow to idle in Park.
    ⚠Do not overfill transmission. Add fluid in 1-quart increments and check level frequently.
    Torque spec

    Transmission Drain Plug30 Nm (22 lb-ft)
11. 11

    Check for leaks and verify fluid level
    With engine idling in Park, inspect all four cooler line connections at transmission and radiator for leaks. Wipe connections dry with shop towel and observe for fresh fluid seepage. Allow engine to reach operating temperature (5-7 minutes). Shift through all gears, pausing 3 seconds in each position, then return to Park. Check fluid level on dipstick with engine running - level should be in HOT range. Add fluid as needed in small increments.

Reassembly

1. Reinstall engine splash shield and torque fasteners to 10 Nm using criss-cross pattern
2. Reinstall front driver side wheel and torque lug nuts to 110 Nm (80 lb-ft) in star pattern
3. Lower vehicle from jack stands and perform final torque check on wheel lug nuts
4. Dispose of used ATF properly at recycling center - do not pour down drain

Verification

• Start engine and verify no leaks at all four cooler line connections with vehicle at operating temperature
• Check transmission fluid level with engine running in Park on level ground - level should be in HOT range on dipstick
• Test drive vehicle for 10-15 minutes, including highway speeds if possible, to circulate fluid through cooler system
• After test drive, recheck fluid level and inspect all connections again for leaks with engine running
• Monitor transmission fluid level and condition over next 100 miles - slight level drop is normal as system fully fills
• Verify smooth shifting in all gears and normal transmission operation with no slipping or delayed engagement

More procedures for this vehicle