Final answer:
The condition that would least likely require crank grinding is excessive thrust wear. This is because thrust wear generally affects the end of the crankshaft that handles axial thrust, whereas crank grinding is more commonly needed to address issues with taper, roundness, or scoring of the main bearing journals.
Step-by-step explanation:
Crank grinding is a process used to restore the tolerance and smoothness of a crankshaft in an engine. In this case, the question asks about which condition would least likely require crank grinding. Excessive taper, out-of-round journal, excessive journal scoring, and excessive thrust wear are all conditions that can lead to the need for crank grinding.
However, the condition that would least likely require crank grinding is excessive thrust wear. This is because thrust wear generally affects the end of the crankshaft that handles axial thrust, whereas crank grinding is more commonly needed to address issues with taper, roundness, or scoring of the main bearing journals.