Transmission Flush

This procedure performs a complete transmission flush on the 2007 Ram 3500 with 5.9L Cummins diesel, removing old ATF+4 fluid and replacing it with fresh fluid to maintain transmission performance and longevity.

Warnings

Tools required

Parts

• Transmission pan gasket × 1 — Use OEM Mopar gasket
• Transmission filter × 1 — Use OEM Mopar filter for 68RFE
• Transmission pan bolts (if corroded) × 1 — Use OEM specification

Fluids

• ATF+4 automatic transmission fluid — 14 qt

Preparation

1. Park vehicle on level surface and set parking brake firmly
2. Place wheel chocks behind rear wheels
3. Allow transmission to cool completely if vehicle was recently operated
4. Raise front of vehicle and support securely on jack stands rated for vehicle weight
5. Verify vehicle is stable before working underneath
6. Locate transmission pan underneath vehicle between front axle and transfer case

Procedure

1. 1

   Position drain pan and loosen pan bolts
   Position drain pan directly under transmission pan. Begin loosening all transmission pan bolts in a crisscross pattern, but do not remove completely yet. Leave two bolts at one corner slightly snug to act as a hinge point.
2. 2

   Drain transmission fluid from pan
   Carefully loosen the last bolts at the opposite corner from your hinge bolts, allowing the pan to tilt and fluid to drain. Be prepared for approximately 5-7 quarts of fluid to drain out. Once fluid flow slows, remove remaining bolts and lower pan completely. Watch for the filter potentially dropping with the pan.
3. 3

   Remove transmission filter
   Locate the transmission filter inside the pan area. The filter may be held by bolts or may simply pull down from the valve body. Remove bolts if present, then pull filter straight down to remove. Additional fluid will drain from the filter cavity.
4. 4

   Clean transmission pan and inspect
   Thoroughly clean the transmission pan interior with shop towels. Inspect for metal shavings, debris, or excessive clutch material. Small amounts of fine material on the magnet are normal. Clean the magnet thoroughly. Remove all traces of old gasket material from both the pan and transmission housing mating surfaces using a scraper, being careful not to gouge the aluminum.
5. 5

   Install new filter
   Install the new transmission filter into the valve body. If the filter uses bolts, hand-tighten them first, then snug evenly. Ensure the filter pickup tube seals properly and the filter is fully seated before proceeding.
6. 6

   Install new pan gasket and pan
   Position the new gasket on the transmission pan, ensuring all bolt holes align. Lift the pan into position against the transmission housing. Start all pan bolts by hand to prevent cross-threading. Tighten bolts in a crisscross pattern evenly and gradually to avoid warping the pan. Final tightening should be snug but not over-torqued (48RE pan bolt spec is approximately 12-14 ft-lbs / 165 in-lbs; verify against factory service manual and do not exceed to avoid pan distortion).
7. 7

   Add transmission fluid through dipstick tube
   Lower vehicle to ground. Locate transmission dipstick tube on passenger side of transmission. Using a transmission fluid pump or long-neck funnel, add approximately 5-6 quarts of ATF+4 fluid initially through the dipstick tube, matching the amount drained. Pour slowly to avoid overflow.
8. 8

   Start engine and cycle through gears
   With parking brake set and foot on brake pedal, start the engine and allow to idle. Shift through all gear positions per the shifter gate (typically P-R-N-D-2-1), pausing 3-5 seconds in each position. Return to Park. This circulates fluid through the transmission and torque converter.
9. 9

   Check fluid level and adjust
   With engine running at idle and transmission in Park on level ground, check the transmission dipstick. Fluid should register in the cold range initially. Add additional fluid as needed to bring level to the proper cold mark. Do not overfill.
10. 10

    Final fluid level verification
    Drive vehicle for 5-10 minutes to bring transmission to operating temperature. Return to level surface, keep engine running in Park, and recheck fluid level. Fluid should now register in the hot range between ADD and FULL marks. Add fluid in small increments if needed to reach proper level.

Reassembly

1. Ensure transmission pan bolts are tightened evenly to prevent leaks
2. Verify no tools or parts were left in the work area under the vehicle
3. Double-check that the drain pan has been removed from under the vehicle before test driving

Verification

• With engine at operating temperature and running in Park, verify fluid level is within hot range on dipstick
• Inspect transmission pan area for any fluid leaks while engine is running
• Test drive vehicle and verify smooth shifting through all gears with no slipping or delayed engagement
• Recheck fluid level after test drive and top off if necessary
• Monitor for leaks during first 50-100 miles of operation

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