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head gasket

482 views 5 replies 6 participants last post by  Don Sutton 
#1 ·
hi what causes head gaskets to blow?
 
#6 ·
As WhiteVan above states mostly overheating - how does it cause head gasket to fail?
When engine heats up block warms and expands - cylinder heats up and expands usually at a faster rate specially if aluminium - cylhead bolts/studs heat up and expand last. This causes extra pressure on cylhead gasket which squashes it like meat in a sandwich. This is planned for if engine runs to normal temperatures. If engine overheats then cylhead gasket gets squashed a little more than normal and when engine cools off the gasket has less pressure on it as gasket has been squashed.
For high mileage cars gasket also wears from longitudinal and lateral expansion and contraction by cylinder head and block.
Corrosion from combustion gasses and electrolytic corrossion from coolant water also afect high mileage vehicles.
In summary keep the vehicle long enough and the head gasket will need to be replaced.
 
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