Intake gaskets can be a very costly failure if you do not service them immediately upon finding them worn. The intake gaskets on GM 3.1 liter, 3.4 liter, and 3.8 liter are very well known for having troubles. These are some vehicles that have intake gasket problems. So if you have a vehicle with one of these engines in them, make sure that you ask your dealership about some of the updated gaskets and intake manifolds to help prevent the failure.
We will discuss how an intake gasket fails. Generally the intake gasket fails so that you will have engine coolant leaking into the engine. This is bad because a liquid is not only uncompressible and can hydro lock a motor but it does not mix with oil. If you run the engine long enough with this leak then you will have a lack of lubrication because there will be water in your oil and water does not have the lubrication properties of engine oil.