Engine Builders: The AERA Technical Committee offers the following information regarding coolant contamination of engine oil for 1996-2003 GM 3.1L or 3.4L VIN J & E engines due to failure of the intake manifold gasket.

GM has redesigned a new intake manifold gasket (p/n 89017279) to reduce the chance of failure. The material used in the revised gasket has been changed in order to improve the sealing qualities of the gasket. When replacing the gasket, the intake manifold attaching bolts must also be renewed with revised bolts that have a pre-applied thread-locking compound. These bolts are available with p/n 11588915 for the shorter bolt and p/n 11588914 for the longer bolt.

Before installing the new gasket, clean all intake manifold and block surfaces of any debris and oils.

Note: An oil leak may result if the vertical bolts (1) shown in Figure 1 are not tightened before the diagonal bolts (2). Diagonal bolts may require a crows foot tool to tighten.

1. Tighten the vertical (1) lower intake manifold bolts to 62 in./lbs. (7 N-m).
2. Tighten the diagonal (2) lower intake manifold bolts to 62 in./lbs. (7 N-m).
3. Tighten the vertical (1) lower intake manifold bolts to 115 in./lbs. (13 N-m).
4. Tighten the diagonal (2) lower intake manifold bolts to 216 in./lbs. (24 N-m).

Engine Builders: The AERA Technical Committee offers the following information regarding loose harmonic balancers, sheared keys and crankshaft damage on 1992-2002 GM 6.5L diesel engines. These conditions have been reported on engines that have been in service a long time and on engines shortly after reinstallation of the vibration balancer.

When the bolt retaining the harmonic balancer loosens, the harmonic balancer may eventually shear the alignment key and further damage of the crankshaft snout, keyway and damper mating surfaces and allow the balancer to spin and relocate its position relative to the crankshaft keyway. Since this damper is externally balanced, a severe vibration may occur.

Since the crankshaft-timing sprocket uses a separate key, a loose balancer may not affect engine crankshaft timing. Continued engine operation may result in component failure. In some cases, a broken crankshaft has resulted from a loose harmonic balancer.

A hardened washer, p/n 23504011, under the balancer retaining bolt head, distributes the clamping load. Engine builders commonly replace this washer when the bolt is removed from the crankshaft. The 5/8˝ fine thread bolt requires an applied torque of 200 ft./lbs. Some AERA members replace the bolt and balancer any time this engine is rebuilt.

Engine Builders: The AERA Technical Committee offers a suggestion to reduce the possibility of seized camshafts on 1990-