AUTOMATIC TRANS. COOLER LINE CRACKED AND LEAKING. GMC Truck Safari

TRANSMISSION APPLICATIONS: 3L80

SUBJECT: AUTOMATIC TRANSMISSION COOLER LINE CRACKED/LEAKING (REPAIR LINE AND SUPPORT)

TRANSMISSION MODELS:

VEHICLE APPLICATIONS: 1982-91 P2,P3 w/6.2L DIESEL ENGINE AND 3L80 A/T

Some 1982-91 P2 & P3 models may experience cracked or leaking automatic transmission cooler lines at or near the transmission fittings.

This condition is usually caused by engine vibration which fatigue cracks the lines at the transmission fittings.

This condition can be corrected by using the following procedure to repair the transmission cooler lines and provide additional support.

VEHICLES INVOLVED

1982 - 1991 P2, P3 models equipped with 6.2L engine and 3L80/3L80-HD automatic transmission.

SERVICE PROCEDURE

- Both the pressure & return lines should be modified regardless of which was leaking.

- Use only hose P/N 12339996. This hose meets specification GM 6260M for use with hot, pressurized automatic transmission fluid.

NOTE: This procedure may be used to repair cracked or leaking automatic transmission cooler lines on all light duty automatic transmissions. If this procedure is used on light duty models other than those listed in the VEHICLES INVOLVED section, support bracket P/N 15666440, listed in step 5 of the following procedure, may require modification.

REMOVE

1. Both the pressure and return lines at the transmission fittings.

2. Seven inches of the original steel lines from the transmission fitting end of both lines.

- It may be necessary to remove more line if the crack is farther from the transmission.

INSTALL

1. Six inches of new 5/16" steel tubing P/N 1324714, double flared at the transmission fitting end and formed to match the shape of the pieces removed.

- This 6" piece of tubing will leave 1" of clearance for movement between the tubing ends.

2. Fittings over the tubing.

- Slightly flare the ends of both lines where the flexible hose will slide over the tubing. This will offer better retention for the hose.

3. New tube/fitting to the transmission.

- Torque the fittings to 35-41 N.m (26-30 Lb. Ft.).

4. Two 4" pieces of hose P/N 12339996 to the cooler lines.

- Use hose clamps P/N 477402 to double clamp each joint making sure the hose clamp screws are on opposite sides of the hose.

- Torque the clamps to 15 lbs. in.

5. Install support bracket P/N 15666440 to the right side rear transmission dust cover bolt. Install clip P/N 723267 over the cooler lines and attach to the support bracket with a 3/4" long #10 screw, flat washer and #10 nut.

6. Start the vehicle and check for leaks.

SERVICE PARTS INFORMATION --------------------------- Quantity Part Number Description Required ----------- --------------------------------------------- -------- 12339996 HOSE, 7.9 MM (5/16") ID X 3050 MM (10')LENGTH 1 1324714 TUBING, 5/16" OD X 25' LENGTH 1 477402 CLAMP, HOSE (.31 TO .75 DIAMETER) 8 15666440 BRACKET, TRANS OIL COOLER PIPE CLIP 1 723267 CLIP 1

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.