Whats the difference between a cracked head and a blown head gasket?

Answer 1

The head gasket is the thin piece of gasket material that is between the engine block and the head. The head gasket fills small imperfections in the head and creates an air-tight seal between the two surfaces, note that it is a seal that is capable of enduring tremendous extremes of heat and pressure. Usually, when a head gasket goes bad, it is caused by a warped head. Heads warp when the engine overheats. In an extreme case, when an engine overheats the head and/or engine block can crack. But in any case, all are caused by an overheated engine. To prevent engine overheating, inspect belts and hoses whenever you purchase fuel. Do it when you check the oil... oh yea... you should probably check the oil regularly as well, but that's another subject. If you see cracks in the hoses or the belt, make the appropriate changes as soon as possible. Hoses also become hard and inflexible. They should be replaced when THAT happens as well. It is not at all unreasonable to expect over 200,000 miles from a properly maintained engine. Heads and head gaskets will last that entire time if the vehicle is properly maintained. The cylinder head is a piece that sits on top of the block and forms the upper part of the combustion chamber. It houses valves, sparkplugs, injectors, and part of the cooling system. It is bolted to the top of the engine block, separated by a thin gasket which seals the space between the two. If this head gasket breaks ("blown gasket"), you can lose compression, necessary for engine combustion, or you could possibly have an exhaust or coolant leak, depending where the break is. "Usually," the replacement of a head gasket is not a big or expensive job...unless there are a lot of engine parts that have to be removed to get to it. A cracked head, on the other hand, may have the appearance of a blown head gasket, i.e., loss of compression or exhaust from the cylinders, but repairing a cracked head means removing it and replacing it, along with the valves, sparkplugs, etc., and can be quite a bit more expensive. Hope that helps. A cracked head means the head itself has a crack in it. Usually between the valves. A blown head gasket means that the gasket that sits between the cylinder head & the engine block has a crach in it allowing the oil and water to mix.