In general, it is recommended to replace head gasket bolts when replacing the head gasket, especially if the bolts are of the "torque-to-yield" type. These bolts are designed to stretch slightly when tightened to their specified torque, creating a tight seal between the head and the block. Once they have been stretched, they should not be reused as they may not provide the necessary clamping force to keep the head gasket in place.
Additionally, some head gasket bolts come pre-coated with a sealing compound. Reusing these bolts could compromise the seal of the new head gasket.
To ensure safety and a secure repair, you should refer to the vehicle's service manual or seek advice from a trusted mechanic as some engines may have specific guidelines, depending on the design and materials used.
