Depending upon the extent of your automotive knowledge and experience, you may or may not be familiar with cylinder heads. These are devices that sit above the cylinders above the cylinder block. It has a platform that holds the combustion chamber in addition to the popper values and spark plugs. This isn't always the case because in flat head engines, the value trains are located in the block, and the cylinder head is a sheet of metal bolted to the cylinder bank. The cylinder block is a casting that has cylindrically shaped holes that house the engine's pistons. You may discover that you're having problems with your cylinder head and/or block during a routine engine tune up. Most of time, cylinder heads and blocks get damaged when your engine becomes overheated. This can happen as a result of radiator or coolant problems. Cylinder heads tend to crack when pistons swell or if hot air pockets get trapped near them. You may not be aware that you're experiencing a cylinder head problem unless you experience a serious engine blowout, which is why it's very important to have your engine examined regularly by a trained professional.