Installation Procedure

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT:

Tighten the exhaust manifold bolts as specified in the service procedure. Improperly installed and/or leaking exhaust manifold gaskets may affect vehicle emissions and/or On-Board Diagnostics (OBD) II system performance.
The cylinder head exhaust manifold bolt hole threads must be clean and free of debris or threadlocking material.

IMPORTANT: Do not apply sealant to the first three threads of the bolt.

Apply a 5 mm (0.2 in) wide band of threadlock GM P/N 12345493, (Canadian P/N 10953488), or equivalent to the threads of the exhaust manifold bolts.
NOTE: Refer to FASTENER NOTICE in Cautions and Notices.
Install the exhaust manifold, NEW gasket and bolts.
Tighten
1. 2.1. Tighten the bolts a first pass to 15 N.m (11 lb ft). Tighten the bolts beginning with the center 2 bolts. Alternate from side-to-side, and work toward the outside bolts.
2. 2.1. Tighten the bolts a final pass to 25 N.m (18 lb ft). Tighten the bolts beginning with the center 2 bolts. Alternate from side-to-side, and work toward the outside bolts.
Install the heat shield, and bolts to the exhaust manifold.
Tighten

Tighten the bolts to 9 N.m (80 lb in).

Fig 1: Installing Heat Shield, & Bolts To Exhaust Manifold - Right (5.3L Engine)
Courtesy of GENERAL MOTORS CORP.
Using a flat punch, bend over the exposed edge of the exhaust manifold gasket at the rear of the left cylinder head.
Install the spark plugs. Refer to SPARK PLUGS .
Raise the vehicle.
Install the exhaust manifold pipe nuts.
Tighten

Tighten the nuts to 50 N.m (37 lb ft).
Lower the vehicle.

Fig 2: Installing Exhaust Manifold Pipe Nuts - Right (5.3L Engine)
Courtesy of GENERAL MOTORS CORP.