Transmission Flush

This procedure performs a complete transmission fluid flush and filter replacement on the 46RE/47RE/48RE automatic transmission used in 1994-2007 Dodge Ram 2500 4WD trucks equipped with the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Transmission filter kit (includes filter and pan gasket) × 1 — Mopar 5013470AA or equivalent
• Transmission pan gasket (if not included with filter) × 1 — Use OEM specification
• Transmission drain plug washer × 1 — Use OEM specification if equipped with drain plug

Fluids

• Mopar ATF+4 — 14 qt

Preparation

1. Ensure transmission has cooled to safe handling temperature (at least 2 hours after operation)
2. Park vehicle on level surface and engage parking brake
3. Raise vehicle and support securely on jack stands rated for vehicle weight
4. Place drain pan beneath transmission pan, positioned to catch fluid from entire pan area
5. Have all replacement parts and full quantity of ATF+4 fluid ready before starting

Procedure

1. 1

   Drain transmission fluid
   If equipped with a drain plug in the transmission pan, remove the drain plug and allow fluid to drain completely. If no drain plug is present, proceed to loosening pan bolts. Allow at least 10 minutes for complete drainage. Inspect drained fluid for metal particles, burnt smell, or excessive debris indicating internal transmission problems.
   Torque spec

   Drain Plug34 Nm (25 lb-ft)
2. 2

   Remove transmission pan bolts
   Loosen all transmission pan bolts in a criss-cross pattern, starting from the center and working outward. Leave two bolts at opposite corners slightly threaded to prevent the pan from dropping. Carefully loosen the remaining bolts allowing the pan to tilt and drain remaining fluid. Once drained, remove the final two bolts and lower the pan. Be prepared for additional fluid spillage.
   Torque spec

   Transmission Pan Bolts12 Nm (9 lb-ft)
3. 3

   Remove old filter
   Locate the transmission filter mounted to the valve body inside the transmission. Remove the filter by pulling it straight down from the valve body pickup tube. Some resistance is normal. Inspect the filter pickup tube seal and O-ring for damage. Check the magnet in the transmission pan for excessive metal debris (some fine powder is normal).
4. 4

   Clean transmission pan and mounting surface
   Thoroughly clean the transmission pan using brake cleaner and lint-free rags. Remove all old gasket material from both the pan and the transmission housing mating surface using a scraper. Be careful not to gouge the aluminum surfaces. Clean the magnet in the pan and inspect for large metal chunks (small metallic powder is normal). Ensure all gasket residue and debris are completely removed.
5. 5

   Install new transmission filter
   Install the new filter by pushing it firmly onto the valve body pickup tube until it seats completely. Ensure the filter O-ring is properly positioned and lubricated with clean ATF+4. The filter should be secure and not move when gently tugged. Verify the pickup tube seal is intact and properly seated.
6. 6

   Install new gasket and transmission pan
   Position the new gasket on the transmission pan (some gaskets adhere to the pan, others to the transmission housing - follow gasket manufacturer instructions). Carefully raise the pan into position, ensuring the gasket does not shift. Start all pan bolts by hand to ensure proper thread engagement before tightening any bolts.
   Torque spec

   Transmission Pan Bolts12 Nm (9 lb-ft)
7. 7

   Torque transmission pan bolts
   Tighten the transmission pan bolts in a criss-cross pattern starting from the center and working outward to the factory spec (approximately 13 ft-lb / 17 Nm — verify in service manual for your transmission). Make multiple passes, gradually increasing torque to avoid warping the pan or crushing the gasket unevenly. Final pass should be at full specification.
   Torque spec

   Transmission Pan Bolts12 Nm (9 lb-ft)
8. 8

   Reinstall drain plug if equipped
   If your transmission pan has a drain plug, install a new crush washer on the drain plug and thread it into the pan by hand. Torque the drain plug to 30 Nm (22 ft-lb).
   Torque spec

   Drain Plug34 Nm (25 lb-ft)
9. 9

   Add initial transmission fluid
   Lower the vehicle to the ground. Locate the transmission dipstick (driver's side of transmission). Using a funnel, add approximately 4 quarts of Mopar ATF+4 through the dipstick tube as an initial fill. A pan-drop and filter service typically only replaces about 4-6 quarts total (not the full dry-fill capacity) - add fluid gradually and verify by dipstick to avoid overfilling.
10. 10

    Start engine and circulate fluid
    Start the engine and allow it to idle. With your foot on the brake, shift slowly through all gear positions on your shifter, pausing 2-3 seconds in each position. Return to Park. This circulates fluid through the valve body and transmission passages. Check underneath for leaks around the pan.
11. 11

    Check and adjust fluid level
    With the engine running at idle and transmission in Park, check the fluid level on the dipstick. The fluid should be warm (not hot). Add additional ATF+4 in 1-pint increments until the level reaches the appropriate cold/warm range on the dipstick (do not overfill; final level is set at operating temperature in the next step). Do not overfill.
12. 12

    Complete fluid level adjustment
    Drive the vehicle for 10-15 minutes to bring the transmission to normal operating temperature (160-200°F). Park on level ground with engine running. Shift through all gears again, then return to Park. Check the dipstick - fluid should be in the 'HOT' range between the hash marks. Add or remove fluid as necessary to achieve proper level. Verify no leaks are present at the pan.

Reassembly

1. Ensure transmission pan bolts are torqued to specification in a criss-cross pattern to prevent leaks
2. Verify drain plug has new crush washer installed if equipped
3. Double-check that final fluid level is correct with transmission at operating temperature

Verification

• Test drive vehicle through all gears to verify smooth shifting with no slipping or harsh engagement
• Recheck transmission fluid level after test drive with engine running and transmission at operating temperature
• Inspect transmission pan area for any signs of fluid leakage after test drive
• Verify transmission shifts smoothly through all gear ranges under light and moderate throttle
• Check that fluid on dipstick is bright red with no burnt smell (if fluid appears dark or smells burnt after fresh fluid added, internal transmission damage may be present)

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