In your vehicle's internal combustion engine, the cylinder head sits on top of the engine block with a cylinder head gasket sandwiched in between. Cylinder head gaskets seal the cylinders, so that coolant and engine oil don't leak into the cylinders. Fluids inside the engine should never mix. That's why making sure your vehicle's gasket is in perfect working condition is important. Cylinders produce an enormous amount of pressure within the engine, so the gasket has to be strong and installed properly with the right bolts and torque. If coolant leaks, the engine can overheat and this can lead to a blown gasket that will need replacement.