When is it necessary to re-torque the exhaust manifold bolts according to Technician B?

Re-torquing the exhaust manifold bolts after the initial warm-up and cool-down is important because the materials of the exhaust manifold and cylinder head expand and contract due to temperature changes. When the engine heats up, the bolts can loosen due to thermal expansion, and when the engine cools down, they may not return to their original torque specifications. By re-torquing the bolts after the engine has gone through a warm-up and cool-down cycle, you ensure that they are securely fastened, preventing exhaust leaks and maintaining optimal engine performance.

The need for re-torquing soon after the initial run helps address any settling of components or potential shifts that may occur as a result of operation, improving reliability and protecting the integrity of the exhaust system. Thus, this practice is critical for maintaining proper sealing and function of the exhaust manifold.