Front Converter Seal - Oil Leak
Number 83-T-12 Section 7 Date 02/83Subject: FRONT CONVERTER SEAL OIL LEAK THM 125C TRANSMISSION (ALL MODELS)
Some THM 125C transmissions may experience a front oil leak condition which is due to the front converter seal coming out of its seat in the case bore. This condition results from an oil pressure back-up behind the converter seal, which causes the converter seal to lose its seat in the case bore.
FIGURE 1:
In servicing any THM 125C transmission for this condition, it is recommended that an oil drainback hole be drilled into the converter seal bore of the transmission case (see Figure 1).
Proper location is important in drilling the hole. Refer to the following service procedure:
SERVICE PROCEDURE
Always refer to the Service Manual for the proper removal and installation procedures of component parts.
1. With the converter removed and the transmission in its holding fixture (tool J-28664), remove the valve body cover and gasket (or R.T.V. sealant).
2. Remove the throttle lever and bracket assembly.
3. Disconnect the wire assembly from the electrical connector.
4. Remove the control valve assembly, spacer plate and gaskets. (Use care not to lose the check balls which are loose.)
5. Disconnect the manual valve from the rod and retainer assembly.
6. Remove the transmission case cover.
7. Remove the drive link assembly (drive sprocket, driven sprocket, chain, thrust washers and bearings).
8. Remove the converter oil seal.
9. Remove the drive sprocket support.
FIGURE 1:
FIGURE 2:
10. Drill (from the seal bore side) a 4.76 mm (3/16") minimum diameter hole 2.03 mm (.080") inside the radius of the converter seal bore (refer to Figure 1). The hole must be drilled through so that it exists the other side of the sprocket support mating face, partially outward from the machined surface as shown (see Figure 2).
USE CARE NOT TO TOUCH THE SEAL BORE DIAMETER WITH THE DRILL BIT.
11. Clean all aluminum chips from the case. The transmission must be thoroughly cleaned and all burrs removed from the drilled hole before reassembly.
12. Install the drive sprocket support and torque the four Torx head bolts to 24 N-m (18 ft.. lbs.).
13. Install a new converter oil seal (part number 8637906 for a 245 mm converter or 8631950 for a 254 mm converter) into the case. Use tool J-28540.
14. Install the drive link assembly.
15. Install the transmission case cover. Torque all bolts to 24 N-m (18 ft.lbs.).
16. Connect the rod and retainer assembly to the manual valve.
17. Install the control valve assembly, spacer plate and gaskets, placing the check balls in their proper locations. Torque all valve body-to-case cover attaching bolts to 11 N-m (8 ft.lbs.), and all valve body to case attaching bolts to 24 N-m (18 ft.lbs.).
18. Connect the wire assembly to the electrical connector.
19. Install the throttle lever and bracket assembly.
20. Install the valve body cover and gasket (or R.T.V. sealant). Torque all bolts to 16 N-m (12 ft.lbs.).
WARRANTY INFORMATION
LABOR TIME
SERIES OPERATION ALLOWANCE
A T3094 3.7 Hr.
J T3094 2.9 Hr.
X T3094 3.7 Hr.
Add additional time of .3 for L4 and power steering. Add additional time of .5 for diesel engine.