GM has issued a TSB #99-04-21-001 to discuss methods to remove stuck transfer case drain plug. The TSB applies to 1998-99 Chevrolet and GMC K1-1 Suburban, Utility Models, 1998-99 Oldsmobile Bravada with NOV136 or 246 transfer case.
The drain plugs in these transfer cases are made from aluminum and have a ¼” square drive recess. The user inserts the male end of a standard ¼” square drive extension into the plug to remove it. If too much torque is applied during installation, the threads on the plug may gall and permanently seize, making removal difficult.
If you cannot remove the plug, you must heat the area with a heat gun. As a safety precaution, you MUST clean all oil and grease from the area to prevent a fire. Do NOT use a torch for this procedure. Use only an electric heat gun and follow the procedure below.
1) Apply heat to the case around the plug for 1-2 minutes. Do NOT apply heat directly on the plug itself. Use only enough heat to loosen the plug.
2) If you plan to replace the plug due to thread damage or rounding of the square recess, DO NOT use a steel or brass replacement plug. These metals are dissimilar and will react with the magnesium case, making future removal even MORE difficult.
3) Replacement plugs are available from the dealer. The part number is 15032997.
4) Torque the new plug to 15ft/lbs. That’s NOT a lot of torque, so don’t get carried away here.
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© 2012 Rick MuscoplatPosted on by Rick Muscoplat