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TSB 21-03-95 Rev A

RWD Automatic Transmission Cold Temperature Cooler Bypass Kit

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Date: Jun. 16, 1995

THIS BULLETIN SUPERSEDES TSB 21-03-95 DATED APR. 14, 1995

Models: 1994-1995 (BR) Ram Truck

1994-1995 (AB) Ram Van/Wagon
1994-1995 (AN) Dakota **
1994-1995 (ZJ) Grand Cherokee
1994-1995 (BR) Ram Truck

Symptoms:

At ambient temperatures of -15 degrees F or below, vehicles equipped with auxiliary transmission coolers nay experience a lark of transmission fluid flow to the transmission. At these low temperatures, the automatic transmission fluid might freeze in the transmission cooler lines restricting fluid flow. This can cause damage to the transmission, and in periods of extended driving, transmission failure my result.  

Diagnosis: 

The cold weather by-pass kit should be installed if any of the following conditions are met:

1. If the vehicle is used in areas of extended cold ambient temperatures (below -15 degrees F).

2. If the transmission has failed in cold ambient temperatures, install the bypass kit when repairing or replacing the transmission. Follow proper cooler flushing and transmission replacement procedures found in the Dodge Ram Service Manual.

Note:   In hot ambient temperatures, this kit will decrease the cooling capacity of the transmission's cooling system. As a result, unless the above stated conditions exist, it is not recommended that this kit be installed.

Parts: 

The following parts should be ordered by the kit part number, however, the individual kit component part numbers are being provided should a single part be needed at a later time.

BR WITH SALES CODE EHC (V-6) & DMD (3.55 AXLE)

1     4798663               By-Pass Assembly Kit

KIT COMPONENTS:

1 4798633      By-pass Assembly Block
1 4798634      By-pass Assembly Adapter
1 4798635      Compression Fitting Coupling
1 4798636      Pressure Line "P"
1 4798637      Radiator Return Line "RR"
1 4798638      Return Line - "R"
1 K6855202   Instruction sheet

 

BR WITH SALES CODE ELF, EMO (V-8)

1     52118668               By-pass Assembly Kit

KIT COMPONENTS:

1 4798633      By-pass Assembly Block
1 4798634      By-pass Assembly Adapter
1 4798635      Compression Fitting Coupling
1 4798639      Pressure Line "P"
1 4798640      Radiator Return Line "RR"
1 4798641      Return Line - "R"
1 K6855202   Instruction sheet

BR WITH SALES CODE ELF, EWA (V-10)

1     47988668               By-pass Assembly Kit

KIT COMPONENTS:

1 4798633      By-pass Assembly Block
1 4798634      By-pass Assembly Adapter
1 4798635      Compression Fitting Coupling
1 4798660      Pressure Line "P"
1 4798661      Radiator Return Line "RR"
1 4798662      Return Line - "R"
1 K6855202   Instruction sheet

For AB, AN, ZJ - see your dealer for parts list.

Figure 1

Repair: 

This bulletin involves the addition of a cold weather by-pass kit to the transmission auxiliary cooler circuit.

1. Disconnect the negative battery cable.

2. Raise the vehicle for access to the transmission housing. The by-pass assembly will be connected to the existing transmission lines and mounted to the transmission housing by means of a by-pass adapter (Figures 1 & 2).

3. During this installation procedure, scan transmission fluid will be lost when the transmission cooler lines are cut (allowing by-pass assembly installation). Take proper precautions and recheck transmission fluid fill level upon completing the installation.

4. If the cold weather by-pass kit has provision for an in-line temperature sensor, the threaded "thermal well" (in the pressure "P" line of the kit) must be plugged with either the temperature sensor from the existing transmission line or the standard pipe plug provided. Consequently, if the vehicle being serviced is equipped with a temperature sensor (i.e., heavy duty BR truck), remove the temperature sensor from the existing line by unthreading and install it in the "pressure" line provided with the kit. Use Mopar Thread Sealant, P/N 4318044, to ensure a leak free seal.

5. Disconnect the pressure and return lines from the transmission housing quick connect fittings.

6. Remove and discard the quick connect fittings from the transmission housing.

7. Apply Mopar Thread Sealant, P/N 4318044, to the threaded by-pass adapter (See Figure 1 to identify the by-pass adapter).

8. Install the threaded by-pass adapter securely into the front pressure port of the transmission housing and torque to 13 ft. lbs.

9. Make sure the snap ring and O-ring are properly installed in their respective grooves on the nose of the by-pass assembly block. Lubricate the O-ring with ATF.

10. Position the by-pass assembly block such that the return port fitting "R" is pointed directly up and the two other fittings are pointed forward.

11. Firmly press the mile nose of the by-pass assembly into the female body of the threaded by-pass adapter until it snaps into place. After snapping into place, the by-pass assembly is permanently attached to the adapter.

NOTE: The bypass assembly can rotate inside the adapter, and removal of the block from the transmission housing (if required) can be accomplished by unthreading the adapter.

CAUTION: If flushing the by-pass assembly is required, it must be removed from the transmission housing. Failing to remove the valve will result in transmission failure by plugging the by-pass valves internal drainback valve.

12. Apply Mopar Thread Sealant, P/N 4318044, to the threaded end (transmission housing end) of the compression fitting.

13. Install the threaded compression fitting securely into the rear return port of the transmission housing and torque to 13 ft. lbs.

14. Using a small tubing cutter, cut the existing pressure Line at approximately 5" from the transmission housing end. Repeat the procedure for the existing return line.

Caution: After cutting the pressure line, mark it with a piece of tape for identification.

15. Connect the return Line "R" to the by-pass assembly block and the rearward return port of the transmission housing. Tighten the compression fitting finger tight, and then wrench tighten it an additional 1/2 turn. Tighten the inverted flare nut to 60 in. lbs.

16. Loosely connect the pressure line "P" to the pressure port fitting "P", on the by-pass assembly block.

17. Loosely connect the radiator return line, "PR" to the "RR" port fitting, on the by-pass assembly block.

NOTE: During the installation of the "P" and "PR" lines, the order may be reversed to aid in the assembly process.

18. Make sure that the existing return line is properly reattached to the hanger bracket and lay the new return line, "RR", beside it. Mark the location of the end of the compression fitting onto the existing return line.

19. Using a small tubing cutter, cut the existing line 1/4" longer than the mark indicates to ensure proper engagement of the compression fitting.

NOTE: When attaching the compression sleeve, refer to figure 2 for proper orientation of the sleeve.

20. Attach a nut and compression sleeve to the Line.

21. Using the compression fitting, connect the return line "RR" on the by-pass assembly to this line. Tighten the nut finger tight, then wrench tighten it an additional 1/2 turn.

22. Disconnect the "RR" line from the by-pass assembly block. This will allow access to tighten the "P" line inverted flare later on in the installation.

23. Make sure that the existing pressure line is properly reattached to the hanger bracket and lay the new pressure line, "P", beside it. Mark the location of the end of the compression fitting onto the existing pressure line.

24. Using a small tubing cutter, cut the existing line 1/4" longer than the mark indicates to ensure proper engagement of the compression fitting.

25. Attach a nut and compression sleeve to the line.

26. Using the compression fittings, connect the pressure line "P" on the by- pass assembly to this line. Tighten the nut finger tight, then wrench tighten it an additional 1/2 turn. Tighten the inverted flare nut to 60 in. lbs.

27. Reattach the inverted flare nut of the "RR" line to the by-pass assembly block and tighten the nut to 60 in. lbs.

28. Recheck to ensure that all connections have been securely tightened.

29. Refer to Figure 3 for view of completed assembly.

30. If applicable, connect the wire harness to the temperature sensor.

31. Lower the vehicle and reconnect the battery cable.

32. Check and adjust the transmission fluid level as outlined in the Rear Wheel Drive Truck Service Manual.

33. Raise the vehicle and check for leaks (idle in Neutral).

CAUTION:  In order to reverse flush the transmission after any service, it is necessary to remove the by-pass assembly from the transmission housing. Failure to remove the by-pass assembly prior to flushing may result in transmission failure.

Notes: 

Policy:    Reimbursable within the provisions of the warranty.

Time Allowance:
Labor Operation No:  21-25-10-91 . . . . . . . . . . . . . . . . . 1. 2 Hrs. Kit, Transmission Cooler Bypass Install

Failure Code:  P8 - New Part 


Thanks to Barry Drodge for supplying this TSB information

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This page was edited on: May 3, 2004