This procedure performs a complete transmission fluid flush on the 10R80 automatic transmission, replacing the fluid and filter to maintain transmission performance and longevity.

Warnings

Tools required

Parts

• Transmission pan gasket × 1 — BC3Z-7A191-A or equivalent
• Transmission filter kit × 1 — BC3Z-7A098-A or equivalent
• Transmission drain plug crush washer (if equipped) × 1 — Use OEM specification

Fluids

• Motorcraft MERCON LV ATF — 11 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow transmission to cool completely (minimum 2 hours after driving)
3. Raise vehicle using floor jack and support securely on jack stands at front and rear frame points
4. Ensure adequate clearance to work underneath transmission (minimum 24 inches recommended)
5. Locate transmission pan, drain plug (if equipped), and filter access area on passenger side of transmission
6. Place drain pan underneath transmission pan area

Procedure

1. 1

   Drain transmission fluid via drain plug
   Locate the transmission drain plug on the bottom of the transmission pan. Position drain pan directly beneath the plug. Using appropriate socket, carefully loosen the drain plug. Allow fluid to drain completely into pan (approximately 5-7 quarts will drain). Once flow stops, remove drain plug completely and inspect crush washer for damage.
   Torque spec

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

   Remove transmission pan bolts
   Locate all transmission pan bolts around the perimeter of the pan (typically 16-18 bolts). Begin loosening bolts in a criss-cross pattern, working from the outside toward the center. Leave two bolts at opposite corners partially threaded to support the pan. Carefully break the pan seal and allow remaining fluid to drain. Remove final two bolts while supporting the pan to prevent dropping.
   ⚠Additional fluid (2-4 quarts) will spill when pan is removed. Ensure drain pan is positioned correctly.
   Torque spec

   Pan Bolts19 Nm (14 lb-ft)
3. 3

   Remove and inspect transmission pan
   Lower the transmission pan carefully and pour any remaining fluid into drain pan. Inspect the bottom of the pan for metal shavings or debris. A small amount of fine material is normal, but large metal particles or chunks indicate internal transmission damage. Clean the pan thoroughly with brake cleaner and lint-free rags.
4. 4

   Remove old transmission filter
   Locate the transmission filter assembly attached to the valve body inside the transmission. The filter is typically held by 2-3 bolts or may be a push-fit design depending on exact configuration. If bolted, remove the filter mounting bolts. If push-fit, carefully twist and pull downward to release. Allow any residual fluid to drain from the filter cavity.
   ⚠Additional fluid will drain when filter is removed. Keep drain pan positioned beneath work area.
5. 5

   Install new transmission filter
   Inspect the filter mounting area for debris and clean if necessary. Install the new transmission filter, ensuring any O-rings or seals are properly seated. For push-fit filters, push firmly until seated with an audible click. For bolted filters, thread bolts hand-tight, then torque to specification in a criss-cross pattern.
   ℹ️Filter bolt torque may use Sensor Bolts specification (12 Nm / 9 lb-ft) if equipped with bolted filter design. Verify with service manual for your specific transmission variant.
   Torque spec

   Sensor Bolts12 Nm (9 lb-ft)
6. 6

   Clean transmission pan mating surface
   Using a scraper or gasket removal tool, carefully remove all old gasket material from the transmission housing mating surface. Take care not to gouge or scratch the aluminum surface. Clean thoroughly with brake cleaner and wipe with lint-free rags. Ensure the surface is completely clean and dry before proceeding.
7. 7

   Install new gasket and transmission pan
   Position the new transmission pan gasket on the pan, ensuring all bolt holes align correctly. Some gaskets are adhesive-backed; others may require careful alignment during installation. Lift the pan into position against the transmission housing, ensuring gasket remains properly aligned. Thread all pan bolts hand-tight before torquing any bolts.
   ℹ️Do not use gasket sealer unless specifically called for by the gasket manufacturer. Most modern gaskets are designed to seal without additional sealant.
8. 8

   Torque transmission pan bolts
   Using a torque wrench, tighten all transmission pan bolts in a criss-cross pattern starting from the center and working outward. Make multiple passes, gradually increasing torque until reaching final specification of 12 Nm (9 lb-ft). Verify all bolts are torqued and none were missed.
   Torque spec

   Pan Bolts19 Nm (14 lb-ft)
9. 9

   Install drain plug with new crush washer
   Install a new crush washer on the transmission drain plug (if your transmission is equipped with one). Thread the drain plug into the pan by hand to avoid cross-threading. Torque the drain plug to 30 Nm (22 lb-ft) using a torque wrench.
   Torque spec

   Transmission Drain Plug30 Nm (22 lb-ft)
10. 10

    Add new transmission fluid
    Locate the transmission fluid dipstick tube on the driver side of the transmission. Remove the dipstick. Using a transmission fluid pump or funnel with extended tube, add 7 quarts of Motorcraft MERCON LV ATF through the dipstick tube. Add fluid slowly to prevent overflow.
11. 11

    Start engine and cycle through gears
    Lower vehicle to ground. Start the engine and allow it to reach normal operating temperature (approximately 5 minutes at idle). With foot firmly on brake pedal, shift transmission through all gear positions (P-R-N-D and manual modes if equipped), pausing 2-3 seconds in each position. Return to Park.
    ⚠Ensure parking brake is engaged and foot is firmly on brake pedal when shifting through gears.
12. 12

    Check fluid level and add as needed
    With engine running and transmission in Park on level ground, check the transmission fluid level using the dipstick. The fluid should be in the cold range on the dipstick. Add additional MERCON LV fluid as needed in 0.5 quart increments until proper level is reached. Do not overfill. After short test drive (5-10 minutes), recheck fluid level when transmission is at operating temperature (160-200°F). Fluid should be in the hot range. Adjust as necessary.

Reassembly

1. Ensure all transmission pan bolts are torqued to specification in criss-cross pattern
2. Verify drain plug is installed with new crush washer and torqued properly
3. Double-check no tools or rags were left in work area
4. Dispose of used transmission fluid properly at recycling center

Verification

• Start engine and verify no fluid leaks from transmission pan or drain plug while engine is running
• Check transmission fluid level with engine at operating temperature - level should be in hot range on dipstick
• Test drive vehicle and verify smooth shifting through all gears with no slipping or harsh engagement
• Recheck fluid level after test drive and top off if necessary
• Inspect ground under vehicle after 24 hours for any signs of fluid leakage
• Monitor transmission operation for next 100 miles to ensure proper function

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