Final answer:
Both Tech A and Tech B provide steps in the process of confirming proper valve seat contact after resurfacing. Tech A uses blue dye for visual inspection, and Tech B recommends valve replacement if the dye does not show full contact, suggesting more investigation is needed rather than immediate replacement.
Step-by-step explanation:
The question pertains to the proper method of checking the fit of a valve in its seat after resurfacing the valve seats, which is a common practice in engine rebuilding or repair. Tech A suggests using blue dye (commonly referred to as machinist's dye or layout fluid) on the valve face, then placing the valve against the seat to check for a complete and even contact pattern. Tech B mentions replacing the valve if the blue dye does not show a continuous mark 360 degrees around the valve face.
The correct approach after resurfacing the valve seats would be to use the dye, as mentioned by Tech A, to ensure the valve and seat are making good contact all the way around. If the dye does not show a full contact pattern, it may indicate that additional work is needed on the valve seat, or that the valve itself is not seating properly and may need to be replaced or further reconditioned, as pointed out by Tech B. However, immediate replacement of the valve is not the only solution; it might be that the seat needs additional work. Both technicians are partially correct, but a systematic approach should be taken to determine the next steps.