Transmission Pan Gasket

Replace the transmission pan gasket on a 1970 AMC Rebel Machine with 390ci V8 to stop leaks and refresh transmission fluid.

Warnings

Tools required

Parts

• Transmission pan gasket × 1 — Use cork or paper gasket compatible with Borg-Warner or Chrysler TorqueFlite automatic transmission
• Transmission filter × 1 — Optional but recommended during pan removal

Fluids

• Automatic transmission fluid (Type A or Dexron) — 5 qt

Preparation

1. Park vehicle on level surface and apply parking brake firmly
2. Place wheel chocks behind rear wheels
3. Raise front of vehicle with floor jack and secure on jack stands at frame rails
4. Verify vehicle is stable before working underneath
5. Position drain pan under transmission pan to catch approximately 4-5 quarts of fluid

Procedure

1. 1

   Loosen transmission pan bolts
   Locate all transmission pan bolts around the perimeter (typically 12-14 bolts). Starting at the rear of the pan, loosen all bolts 2-3 turns but do not remove them yet. This allows fluid to begin draining in a controlled manner from the rear edge first.
2. 2

   Drain transmission fluid
   Carefully loosen the rear bolts further while holding the pan up with one hand. Allow the rear of the pan to drop slightly so fluid drains into the catch pan. Work slowly around the pan perimeter, loosening bolts gradually to control fluid flow. Once most fluid has drained, remove all bolts except two at the front corners.
3. 3

   Remove transmission pan
   Support the pan with both hands and remove the final two front bolts. Lower the pan carefully, tilting to drain remaining fluid. The pan may be stuck to the transmission with old gasket material and may require gentle prying with a scraper or tapping with a rubber mallet to break the seal.
4. 4

   Inspect magnet and pan interior
   Remove the magnet from inside the pan and inspect for metal shavings. A small amount of fine gray powder is normal; large metal particles or chunks indicate internal transmission wear. Clean the magnet thoroughly and set aside for reinstallation. Inspect pan interior for cracks or damage.
5. 5

   Remove and replace transmission filter (if applicable)
   If replacing the filter, locate the filter attached to the valve body inside the transmission. Remove the filter retaining bolts or clips (typically 2-3 bolts). Pull the filter and pickup tube straight down to remove. Install new filter with new O-ring or seal, pressing firmly into place, and secure with retaining hardware.
6. 6

   Clean transmission pan mating surface
   Use gasket scraper to remove all old gasket material from the transmission pan mating surface on the transmission case. Clean thoroughly until bare metal is visible with no gasket residue remaining. Use brake cleaner and a rag to remove all debris. Do not allow any material to fall into the transmission.
7. 7

   Clean transmission pan
   Remove all old gasket material from the pan flange using the gasket scraper. Clean the pan thoroughly inside and out with brake cleaner or degreaser. Dry completely with clean rags. Inspect the pan flange for warping or damage that could prevent proper sealing.
8. 8

   Install new gasket on pan
   Place the new gasket on the transmission pan, aligning all bolt holes. If using a cork gasket, you may apply a thin bead of gasket sealer to help hold it in position, though this is not required. Ensure gasket sits flat with no wrinkles or folds. Reinstall the cleaned magnet inside the pan.
9. 9

   Position and install transmission pan
   Carefully lift the pan with gasket into position against the transmission case. Start all bolts by hand, threading them 2-3 turns to hold the pan in place. Ensure the gasket remains properly aligned as you install bolts. Once all bolts are started, tighten them in a crisscross pattern working from the center outward, gradually bringing the pan up evenly.
10. 10

    Final torque transmission pan bolts
    Torque all pan bolts in a crisscross pattern to the manufacturer specification. Without factory torque specifications in the database, use 12-15 ft-lbs for typical automatic transmission pan bolts, applied gradually in multiple passes. Do not overtighten as this can warp the pan and cause leaks.
11. 11

    Refill transmission with fluid
    Lower vehicle to the ground. Locate the transmission dipstick (typically on passenger side of transmission). Remove dipstick and insert funnel. Add 4 quarts of Type A or Dexron automatic transmission fluid. Start engine and allow to idle. With parking brake applied and foot on brake pedal, shift through all gear positions, pausing 2-3 seconds in each. Return to Park.
12. 12

    Check fluid level and top off
    With engine running at idle and transmission in Park, check fluid level on dipstick. Fluid should be in the 'ADD' or 'COLD' range. Add fluid in half-quart increments until proper level is reached. Do not overfill. After vehicle reaches operating temperature, recheck fluid level in the 'HOT' or 'FULL' range and adjust as needed.

Reassembly

1. Ensure all pan bolts are torqued evenly to prevent warping and future leaks
2. Verify transmission dipstick is fully seated after final fluid level check
3. Inspect underneath vehicle after test drive for any signs of leakage

Verification

• Check for fluid leaks around transmission pan perimeter with engine running
• Verify transmission shifts smoothly through all gears without slipping or harsh engagement
• Confirm transmission fluid level is in proper range on dipstick when at operating temperature
• Test drive vehicle and recheck fluid level and pan area for leaks after 10-15 miles of driving

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