How to Replace the Intake Manifold Gasket on a Chevy 454by Moss Strohem
While not common, intake manifold gaskets have been known to fail or leak, requiring that they be replaced. The Chevy 454 CI engine intake manifold must be removed in order to replace these gaskets. This engine has cooling passages running through it, so this repair requires draining the cooling system first. As well, the ignition system distributor is housed at the rear of the manifold, so it also needs to removed. If the goal is to replace the factory manifold with an aftermarket performance version, the process is the same.
Removing the Manifold and Gasket
Place the engine coolant drain pan beneath the radiator, open the drain petcock and begin draining.
Remove any wires that prevent the intake manifold from being lifted off. Many accessory and ignition wires are routed near and over the intake manifold. Remove any additional coolant lines from fittings on the manifold. By now, the radiator should be drained enough that the coolant level in the engine has dropped.
Remove the distributor clamp bolt, clamp and distributor.
Remove all intake manifold bolts. Pry and lift the intake manifold up and off of the engine. The carburetor or injection throttle body can remain attached to the manifold, provided you can lift the extra weight. You may need a helper for this task.
Lay shop rags or towels in the center of the engine to prevent debris from falling into the lifter valley. Carefully scrape and clean the old gasket material off of the cylinder heads and the front and rear rails of the lifter valley and the engine block. Do not use an abrasive power sander, as this can damage the gasket surfaces and prevent proper sealing.
Installing the Manifold and Gasket
Set the rubber gaskets along the front and rear rails of the lifter valley. Apply a dollop of silicone at the end of each rail gasket.
Set the new composite head/intake manifold gasket on each cylinder head surface so that each end just rests in the small portion of silicone at the end of the rubber rail gaskets.
Replace the intake manifold assembly carefully. Lower it straight down onto the new gaskets so that they are not moved out of place. A helper may be needed for this part of the procedure.
Install all manifold bolts and tighten -- in sequence from the center out -- to the recommended torque value.
Replace all wiring and hoses. Reinstall the distributor. Refill the cooling system with fluid. Restart the engine and check for leaks.
- If it appears that any engine coolant got into the lifter valley when removing the intake manifold, it is a good idea to drain and replace the engine oil.