General Motors advises closely inspecting the intake manifold after severe internal engine damage on 2008 and earlier Saturn, Hummer H2 and H3 and Saab 9-7X, due to the potential for debris to be trapped inside the manifold ports.
When replacing an engine due to internal damage, extreme care should be taken when transferring the intake manifold to the new engine longblock. Internal damage may result in the potential discharge of internal engine component debris in the intake manifold via bent, broken or missing intake valves.
After removing the intake manifold, closely inspect the cylinder head intake ports to see if the valve heads are still present and not bent. Usually when the valve heads are missing or sufficiently bent, internal engine component debris will be present to varying degrees in the intake port of the cylinder head.
If this debris is present in any area of the cylinder head intake ports, the intake manifold should be replaced due to the complex inlet runner and plenum design, making it difficult or impossible to verify cleaning and debris removal.