Coolant loss with no external leak, white smoke from the tailpipe, oil in the coolant or a compression loss between two cylinders all point here.
Head gaskets are thickness-specific because they set compression ratio and valve clearance, and they are matched to the engine code and to the surface finish the manufacturer specifies. A gasket for a different thickness will run and will be wrong in a way that only shows up as a compression or a clearance problem. Head bolts on most modern engines are torque-to-yield and must not be reused, and the torque sequence has to be followed exactly.
Listings state the thickness, the material and the engine codes covered. Have the head pressure-tested and checked for flatness before fitting a new gasket, otherwise the replacement will fail in the same place.
