What would cause my cylinder head to crack on my 4.3 2000 Envoy?
The cylinder head is a crucial part of all combustion engines, and cylinder head cracking can result in catastrophic damage to the engine. In some cases, cylinder head cracking may result in such severe injury to the engine that it must be replaced. As a result, most motorists try to prevent cylinder head cracking, as an ounce of prevention in this case is worth many pounds of cure. The causes of cylinder head cracking are all relatively simple and easy to prevent, except in the case of mechanical parts failure through no fault of the operator.
The cylinder head, used in combination with a head gasket, seals the cylinders of the car, along with other parts associated with them. The cylinder head is customized for the vehicle, and has very precisely milled surfaces to provide a smooth and flush fit with all connecting parts. In the case of a minor crack, the cylinders may lose compression and misfire. Major cracks can cause severe damage to the cylinders of the engine. For this reason, when replacing either the cylinder head or the head gasket, make sure that you are using the correct parts, including bolts, for the job.
Even a brand new car can experience cylinder head cracking if parts have been installed incorrectly or if there are weaknesses in the metal. Especially in the case of a vehicle which is still under warranty, drivers should contest the cylinder head cracking with the dealer. Be certain to inspect any vehicle before you purchase to check for weak spots in the metal or incorrectly installed components. This includes the cylinder head gasket, because improper installation of this vital part can cause cylinder head cracking.
Cylinder head cracking has become more common as car manufacturers use mixed metals in their engines. Many vehicles, for example, have a solid cast iron engine block but an aluminum cylinder head. These two metals expand at different rates, and this can lead to cylinder head cracking.
The most common cause of cylinder head cracking is overheating. When a vehicle overheats, it puts stress on all of its metal components, including the cylinder head, which is often at the center of the heat. This can cause the head gasket to fail, which may lead to cylinder head cracking as the components warp and pressure begins to leak. All drivers should properly maintain their vehicles to prevent overheating.
Many drivers mistakenly pour cool water into the radiator when their vehicles overheat, in an attempt to bring the temperature down. This is not a good idea, because the rapid temperature change will cause cylinder head cracking due to thermal stress. In a case where the cylinder head survives overheating, the driver may inadvertently destroy it by trying to do good.
To prevent overheating, make sure that your radiator is filled and in good condition, with a tightly sealed cap. Check to be certain that your engine thermostat is in good working order, and accurately reflecting the temperature. Make sure that you have no leaky belts or stretched hoses, and that the fan is working effectively. If your car does overheat, stop, turn off the engine, and allow it to cool completely before adding water.
Cylinder head cracking can also be caused by localized hot spots in the engine, which usually represent a failure in some portion of the cooling system. Always make sure that hot spots are addressed, particularly if your head gasket has failed and required replacement recently. Hot spots are often caused by uneven expansion of engine parts, leaky hoses, and pre-ignition in the cylinders of the engine.
If your car has overheated, check the cylinder head and gasket for signs of cracking or warping. If the cylinder head has warped even slightly out a flush state, it will cause cylinder head cracking. In this case, the head gasket may need to be replaced and the cylinder head should be ground even again before it cracks.
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Jan 21, 2009 |
2000 GMC Envoy