D250 3/4 Ton Pickup 2WD V8-360 5.9L VIN 5 4-bbl (1988)
Transmission Cooler: All Technical Service Bulletins
A/T - Auxiliary Cooler Freezes Up/Fluid Loss
Models
1988-89 AB, AD & AN Bodies And 1988-89 AM Bodies
Subject
Auxiliary Oil Cooler Freeze-Up
Index
TRANSMISSION
Date
February 27, 1989
No.
07-01-89
P-820
(C07-01)
BODY CODE LEGEND
AM - DIPLOMAT/NEWPORT/FIFTH AVENUE AN - DAKOTA/DAKOTA SPORT AB - RAM 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
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.