Loss of coolant, white smoke from the tail pipe, bubbling into the reservoir when engine isn't overheating.

A "sniffer" test can be done to confirm a suspected leaking head gasket. Air is drawn from the radiator through a glass cylinder with two chambers partially filled with a special dark blue liquid. If combustion gases are leaking into the cooling system, the liquid will turn bright yellow.

Answered by caradiodoc (expert)
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