Your Chevrolet's exhaust manifolds and gaskets are subject to a lot of abuse under normal driving conditions. Being bolted directly to the exhaust outlet of the engine, the exhaust manifolds experience extreme heat transfer from the engine block. For this reason, the rubber gaskets are prone to breaking down, especially on a high-mileage Chevrolet. Faulty exhaust manifold gaskets allow for exhaust leaks, which can lead to a drop in your Chevy's peak horsepower and fuel mileage.
Allow adequate cooling time before working on your Chevrolet's exhaust system, as it is substantially heated under normal driving conditions. Disconnect the cables from the battery terminals, to avoid the risk of electrical shock when working with the engine's wiring.
Disconnect the spark plug wires by hand. These are connected to the tops of the spark plugs, into the A.I.R. tube assembly, just above the exhaust manifold. Use a socket wrench to unscrew and remove the spark plugs. Remove the A.I.R. tube assembly, by removing all securing hex bolts. You should now have clear access to your Chevrolet's exhaust manifold.
Remove the hex bolts that secure the exhaust manifold to the engine, located along the manifold mounting flange. This will allow you to pull the exhaust manifold away from the engine slightly, allowing for removal of the faulty exhaust manifold gasket. Slide a new one in place, and reinstall the exhaust manifold mounting bolts. Ensure that the manifold bolts are extremely tight, to avoid future exhaust leaks.
Reinstall the A.I.R. tube assembly, spark plugs, and spark plug wires and reconnect the vehicle battery.
