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Measuring Cylinder Head Warpage
Before installing a cylinder head, the casting should be checked for warpage to prevent a head gasket leak Figure 74. A warped cylinder head will not clamp against the block deck properly to allow the gasket to seal correctly. If an engine has overheated, a leak has occurred, or liner protrusions have not been properly established before the head has been installed, it is particularly important to check the deck surface for warpage. To measure cylinder head warpage, follow the steps in Skill Drill 9-1.
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Technicians Tip |
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Loss of engine coolant or excessive cooling system pressure can often be attributed to a cylinder head gasket leaking externally or internally or to a cracked cylinder head. Air bubbles originating from the engine block will appear in the radiator, and pressure will build rapidly in the cooling system, which will cause the engine to lose coolant or even push coolant out of the engine under heavy load. Technicians can check for hydrocarbons or carbon monoxide in the gas bubbles on gasoline engines but not on diesel engines because only air is present in the cylinders during the compression stroke. Test kits that measure carbon dioxide (CO2) gas in coolant are used to evaluate gas bubbles in diesels. |
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FIGURE 09-74: Inspecting a cylinder head for warpage using a straight edge and a thickness gauge.
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