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Updated Torque Specs for 1999-2003 GEN III Vortec Engines
A new exhaust manifold bolt and torque specification was
introduced to the GM GEN III Vortec small block V8 engine beginning
with the 2004 model year. When servicing and GEN III Vortec small block
exhaust manifolds, the exhaust manifold bolts should be replaced.
Use GM p/n 11518860 Exhaust Manifold Bolt
Apply a .2˝ wide bead of high temperature threadlocker to the threads of the exhaust manifold bolts before installing.
p/n 12345493 GM High Temperature, High Strength Threadlocker (U.S.)
p/n 10953488 GM High Temperature, High Strength Threadlocker (Canada)
When tightening the exhaust manifold bolts, it should be done with two
passes. First tighten the two center bolts on the exhaust manifold.
Then tighten the rest of the bolts, alternating from side to side,
while working towards the outside bolts.
Refer to the following torque sequence when installing exhaust manifold bolts:
First pass tighten to 89 in.lbs. (10 Nm)
Second pass tighten to 15 ft.lbs. (20 Nm)
Some or all of the preceding technical information was provided by the
Automotive Parts Remanufacturers Association (APRA). For more
information on technical bulletins available through APRA call
703-968-2772 or visit www.AutoBulletins.com.