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TSB 07-01-89

Auxiliary oil Cooler Freeze-Up

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Date: February 27, 1989

Models: 1987 -1989 AD - Dodge Ram Pickup/Ram Charger

1988-89 AB, AD & AN Bodies And 1988-89 AM Bodies

AM - DIPLOMAT/NEWPORT/FIFTH AVENUE
AN - DAKOTA/DAKOTA SPORT
AB - RAN VAN/WAGON
AD - RAM PICKUP/RAMCHARGER SPORT UTILITY

Symptom/Condition:

At ambient temperatures of -10° F or lower subject model vehicles equipped with auxiliary transmission coolers (NHB) sales code, when driven at highway speeds, may begin losing transmission fluid. This fluid loss is due to the transmission oil cooler "freezing" and restricting oil flow through the system, resulting in overheating of the fluid in the transmission case. When the vehicle is stopped, transmission fluid will "burp" out of the dipstick tube and front pump vent. Driving the vehicle for an extended period under these conditions can allow additional fluid to be lost and damage to the transmission could result.

Diagnosis:

- Examine the condition of the transmission fluid. If it is dark in color and/or has a strong or burned odor, the fluid has been overheated.

- If the fluid level is checked per the normal procedure and found to be at or below the add mark, and there is evidence of fluid leakage at the front pump vent inside the bell housing, the transmission may be experiencing excessively high fluid temperatures.

If either or both of these conditions occur, the following repair procedures should be followed, to eliminate the potential for cold ambient oil flow restriction by installing an oil cooler bypass connector in the system plumbing.

Parts Required:

1 - Connector - Bypass                  4401013 4
4 - Clamps                                     6032839
2 - Connector - Hose-to-Hose       4266356

Repair Procedure:

This procedure involves the removal, disassembly, inspection, reconditioning (if necessary) of the transmission, inspection of the torque converter flushing of the transmission cooler and lines and installing an oil bypass connector in the system plumbing.

1. Remove, disassemble, inspect and assemble the transmission as outlined in the appropriate Service Manual.

2. Remove and inspect torque converter.

3. Flush transmission cooler and lines.

4. Install torque converter and transmission as outlined in the appropriate Service Manual.

5. Using Figure 1, 2, or 3 as necessary, cut the cooler hoses as shown and insert PN 4401013 connector and install PN 6032839 clamps.

6. Fill transmission and operate in gear, check for leaks.

NOTE: THE TWO (2) HOSE-TO-HOSE CONNECTORS PN 4266356 ARE TO BE GIVEN TO THE CUSTOMER. INSTRUCT THE CUSTOMER THAT IF THE VEHICLE IS TO BE OPERATED UNDER SEVERE TRAILER TOW AND HIGH AMBIENT TEMPERATURE CONDITIONS, IT IS ADVISED THAT THE CONNECTOR BY-PASS BE REMOVED AND THE HOSE-TO-HOSE CONNECTOR BE INSERTED.

POLICY:     Reimbursable within the provisions of the warranty.

TIME ALLOWANCE:
Labor Operation No.        21-25-20-90 . . . . . . . . . . . 0.3 Hrs.

FAILURE CODE:   08 - Blocked