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How to Change an Exhaust Manifold in a Chevrolet Impala 3400

by Cayden Conor

The Chevrolet Impala 3400 uses the 3.4-liter V-6 engine, which has an exhaust manifold on each side of the engine. Though you might not have to change the manifolds on both sides of the engine, you should at least change the gasket on the side you are not replacing, unless it has been changed recently. Finding a replacement exhaust manifold might be chore, as this part rarely breaks. If you cannot find it a an auto parts store, check the dealership and the used auto parts yards.

Left Side

Loosen the clamps on the air duct and throttle body inlet duct, using the screwdriver, pliers or a socket, depending on the type of clamp used -- different years may use different types of clamps, or a previous owner may have used a different type of clamp. Remove the air ducts. Remove the air filter and air box, using the appropriate socket.

Remove the right engine mount-strut bracket, exhaust crossover pipe shield and the exhaust crossover pipe nuts on the left manifold, using the appropriate sockets. Remove the exhaust manifold heat shield, using the appropriate socket. Remove the exhaust manifold, using the appropriate wrench to remove the bolts at the engine and the nuts at the collector.

Install the new manifold and new gaskets at the collector and the engine. Torque the bolts to 12 foot-pounds of torque. Reinstall the exhaust manifold heat shield. Torque the bolts to 89 inch-pounds of torque.

Reinstall the crossover pipe and torque the bolts to 18 foot-pounds of torque. Reinstall the crossover pipe heat shield, tightening the bolts to 89 inch-pounds of torque. Install the right engine mount-strut bracket, throttle body air inlet duct and the air cleaner box and its ducts.

Right Side

Remove the throttle body air inlet duct, using the appropriate socket, screwdriver or pliers, depending on the type of clamp on the duct. Unbolt and remove the accelerator cable bracket from the throttle body.

Unplug the manifold air pressure, or MAP, sensor, then remove it, using the appropriate sockets. Unbolt and remove the exhaust manifold recirculation, or EGR, pipe, using the appropriate socket.

Mark the spark plug wires with the tape and marker. Pull them off the spark plugs. Unplug the wiring harness connectors on the ignition module and the ignition coils. Unbolt and remove the module and coils. Unplug the oxygen sensor wiring harness connector.

Remove the evaporative emissions, or EVAP, solenoid bracket. Remove the exhaust crossover heat shield, using the appropriate socket. Remove the exhaust crossover pipe from the manifold, using the appropriate socket or wrench.

Unbolt the catalytic converter from the manifold, then remove the exhaust manifold heat shields, using the appropriate sockets and wrenches. Unbolt the exhaust manifold from the engine, then remove the manifold.

Install the new manifold with a new gasket, tightening the bolts to 12 foot-pounds of torque. Reinstall the exhaust manifold heat shields and tighten the bolts to 89 inch-pounds of torque. Reinstall the catalytic converter, tightening the bolts to 24 foot-pounds of torque.

Reinstall the crossover pipe and tighten the bolts to 18 foot-pounds of torque. Reinstall the crossover pipe heat shield, tightening the bolts to 89 inch-pounds of torque. Reinstall the EVAP solenoid bracket and the oxygen sensor connector.

Reattach the spark plug wires, ensuring that you put them on the proper plugs, and that the wires snap onto the plugs. Reinstall the module, coils and the bracket. Reinstall the EGR pipe and tighten the bolts firmly. Reinstall the MAP sensor and plug it in. Reattach the accelerator cable onto the throttle body. Reinstall the throttle body air inlet duct.

Items you will need

About the Author

Cayden Conor has been writing since 1996. She has been published on several websites and in the winter 1996 issue of "QECE." Conor specializes in home and garden, dogs, legal, automotive and business subjects, with years of hands-on experience in these areas. She has an Associate of Science (paralegal) from Manchester Community College and studied computer science, criminology and education at University of Tampa.

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