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 729 (ENGINE CONTROLS (INTRODUCTION) -- 5.7L)REPAIR INSTRUCTIONSSECONDARY AIR INJECTION (AIR) CHECK VALVE/PIPE REPLACEMENT - BANK 2REMOVAL PROCEDURE

1999 GMC Forward Control 5.7 R, Automatic

Removal Procedure

1999 GMC Forward Control 5.7 R, AutomaticSECTION Removal Procedure

WARNING: This page is about a different car, the 2004 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

Remove the intake manifold. Refer to Intake Manifold Replacement in Engine Mechanical.

CAUTION: Allow the engine to cool before servicing the secondary air injection AIR system in order to reduce the chance of severe burns.

Remove the clamps and secondary air injection (AIR) hoses from the AIR system right pipe.

Fig 1: Cylinder Head & Air Pipe Bolt

Courtesy of GENERAL MOTORS CORP.

Remove the AIR pipe bolt from the cylinder head.

Fig 2: Right Air Pipe

Courtesy of GENERAL MOTORS CORP.

Remove the right AIR pipe from the manifold.
Unscrew the check valve from the AIR pipe.
Before replacing a check valve, test the valve for proper operation.
1. Install a vacuum pump to the nipple side of the check valve, AIR pump side.
2. Pump the vacuum pump to 10 inches Hg and observe the gage.
3. Replace the check valve if the vacuum bleeds down to zero within 5 seconds.

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.