When replacing a head gasket torque down the head and adjust the valves. This first sequence is done on a freshly assembled, not runnable, cold engine with a new head gasket. After first warm-up (full operating temperature) of a freshly assembled runnable engine, loosen the radiator cap and re-torque the engine while still warm. Use correct tightening sequence, but loosen the bolts one or two turns, one at a time and re-torque to spec then move to the next. Adjust the valves again when engine cools. The last re-toque sequence is done after 500 miles approximately, on a warm engine, adjust the valves again when engine cools. Always relieve the pressure in the cooling system before loosening any head bolts. Normal maintenance should include the re-toque and valve adjustment every 12,000 to 15,000 miles. Engines with leaky head gaskets, stuck head bolts and rusted head bolts are usually those engines which have not ever had head re-torqueing maintenance. Oiling the head bolts during the original engine assembly is critical for getting correct torque specs. Some bolt torque charts give different values for torqueing bolts oiled or dry. Naturally it is not necessary to remove the bolts and oil them during re-torque in most cases since the original oil from engine assembly, should still be present on the threads. In addition, just the act of loosening the bolt for re-toque, on a warm engine will allow some oil to migrate under bolt heads and down along the bolt shaft to the threads. On rare occasions, during re-torque service, I have come across issues of rusted head bolts and stuck head bolts from dry assembly (no oil) on bolt threads. During these instances, I have removed each bolt one at a time, in sequence, and cleaned and oiled the threads then re-installed and torqued to spec. Do not fail to loosen the radiator cap before loosening any head bolt. The pressure in the cooling system could allow some coolant leakage into the threads of the loosened head bolt or worse.
