Aluminum heads are famous for warping which causes the head gasket to leak.
Sometimes it may just be a poorly designed gasket for the motor run and they fail like clockwork.
With the head off put a straight edge or ruler on its mating surface and inspected it for warping, if need be take it to be resurfaced / shaved.
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Save gas
Ride a Mtn bike for errands exercise entertainment and outright fun
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