A/T LINES CRACKED/LEAKING (REPLACE LINES/INST. BRACKET)

SUBJECT: AUTOMATIC TRANSMISSION COOLER LINES CRACKED/LEAKING

MODELS: 1988-92 C/K TRUCKS EQUIPPED WITH 6.2L DIESEL ENGINE AND 4L60 (MD8) OR THM400 (M40) AUTOMATIC TRANSMISSION

Some owners of 1988-92 C/K trucks equipped with a 6.2L diesel engine and a 4L60 or THM400 (RPO MD8 or M40) automatic transmission may experience cracked or leaking automatic transmission cooler lines at or near the transmission fittings.

These cracks may be caused by the cooler lines going into resonance or vibrating at low engine idle speeds causing the lines to fatigue. To correct this condition, replace the cracked/leaking lines and install a support bracket.

SERVICE PROCEDURE

1. Replace the cracked/leaking line(s) using tubing (P/N 1324714).

Double flare both ends of the line and form the line to match the shape of the line which was removed.

2. Install a bracket assembly (P/N 15684042 (C-Truck) (Figure 1) or P/N 15684043 (K-Truck) (Figure 2)) to the transmission inspection cover bolt.

3. Install a clamp (P/N 15518639) around the transmission cooler lines and attach it to the bracket assembly with a bolt (P/N 11508023) (Figures 1 and 2).

SERVICE PARTS INFORMATION

Part Qty. Number Description Reqd. ------ ----------- ----- 15684042 Bracket, Trans Oil Clr Pipe 1 Clip (C-Truck)

15684043 Bracket, Trans Oil Clr Pipe 1 Clip (K-Truck)

15518639 Clamp, Fuel Supply 1

11508023 Bolt, M6x1x16 1

1324714 Tubing, 5/16" 0D x 25' As Required Parts are currently available from GMSPO.

WARRANTY INFORMATION

For vehicles repaired under warranty use:

Labor Labor 0p. Description Time ----- ----------- ----- K5262 Repair/Replace Upper Trans 0.7 hrs. Cooler Line and Install Bracket

K5263 Repair/Replace Lower Trans 0.7 hrs. Cooler Line and Install Bracket

K5267 Repair/Replace Both Trans 1.0 hrs. Cooler Line and Install Bracket

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.