Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 402 (ENGINE EXHAUST SYSTEM)REPAIR INSTRUCTIONSEXHAUST MANIFOLD PIPE REPLACEMENT (LX5)INSTALLATION PROCEDURE

1999 GMC Forward Control 5.7 R, Automatic

Installation Procedure

1999 GMC Forward Control 5.7 R, AutomaticSECTION Installation Procedure

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Refer to FASTENER NOTICE .

Place a NEW exhaust manifold pipe gasket over the right exhaust manifold studs.
Position the exhaust manifold pipe to the right exhaust manifold.
CAUTION: Refer to FASTENER NOTICE .
Install the two nuts attaching the exhaust manifold pipe to the right exhaust manifold.
Tighten

Tighten the exhaust manifold pipe nuts to 50 N.m (37 ft lbs).

Fig 1: Installing Exhaust Manifold Pipe & Gasket
Courtesy of GENERAL MOTORS CORP.
Place a NEW catalytic converter gasket over the catalytic converter studs.
CAUTION: Do not over-flex or damage the flex decoupler joint when moving the flex decoupler joint from normal mounting position. The flex decoupler joint will flex a maximum of six degrees which is equivalent to the pipes connected at the joint which move 1 inch for each foot length of pipe. A three foot pipe would move a maximum of three inches.
Position the catalytic converter to the exhaust manifold pipe.
Install the four nuts in order to secure the catalytic converter to the exhaust manifold pipe.
Tighten

Tighten the catalytic converter nuts to 25 N.m (18 ft lbs).

Fig 2: Installing Catalytic Converter To Exhaust Manifold Nuts

Courtesy of GENERAL MOTORS CORP.

Lower the vehicle.

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.