Info - Use of Heat for Difficult to Remove Transfer Case Fill and Drain Plugs

This bulletin is being revised to add the 99 model year and part information. Please discard Corporate Bulletin Number 76-74-03 (Section 7--Transmission).

Some transfer case fill and drain plugs may be difficult to remove. In some cases, the plug may be "rounded out" attempting to remove the plug. These plugs are made of aluminum and have a 1/4 inch square hole designed to receive a 1/4 inch square drive extension. Installation torque may have been too high causing difficulty in removal.

Caution: To help avoid a fire, thoroughly clean the area around the fill and drain plugs of grease build-up before heating and use only an electric heat gun. DO NOT USE AN OPEN FLAME. If sources other than an electric heat gun are used, the transfer case may catch fire and cause personal injury.

In cases where the plugs cannot be loosened, the use of an electric heat gun may make plug removal possible. Heat should be applied to the case around the plug, not directly on the plug, for one to two minutes. Use only enough heat to loosen the plug. Also, fully insert the 1/4 inch square drive extension onto the plug before turning the plug.

Important: Do NOT use plugs made of steel or brass. These may cause a severe corrosive reaction when in contact with the magnesium case, making future removal even more difficult.

If the fill and drain plugs are damaged during removal and must be replaced, use only aluminum replacement plugs. Replace the drain and fill plugs (internal, square drive tool access design) with the EXTERNAL HEX DESIGN plug, P/N 15032997.

When you install the transfer case fill or drain plug, tighten the plug to 20 N·m (15 lb ft).

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: