LO 5-1 List and explain the factors requiring technicians’ skills related to precision measurements

LO 5-01: List and explain the factors requiring technicians’ skills related to precision measurements.

With increasingly precise dimensional controls used by engines and subcomponents, technicians need to be skilled in the correct selection and use of precision tools and measurement more than ever before. Skills like these are necessary in order to precisely measure components to determine serviceability—a term describing the process of inspecting and evaluating a part to make a correct recommendation for replacement, repair, or return of a component to service as it is. Technicians are also responsible for service procedures that may involve measuring and cutting parts with great accuracy, such as installing and adjusting cylinder liner heights or when replacing valve seats and poppet valves in cylinder heads. Measuring runout of components such as a flywheel housing or the amount of lift provided by a camshaft lobe are examples of other, almost countless service procedures requiring precision measurement FIGURE 2. When not performing these tasks, technicians may need to make specific service recommendations or perform inspections on machined components after machining repairs are completed. To do this, technicians should be guided by a correct understanding of how these processes are performed and how to inspect serviced or rebuilt components to evaluate whether they are suitable for installation. Machining cylinder heads containing replaceable valve guides and seats or refinishing block decks, crankshafts, cylinder bores, and liner counterbores are just a few examples of the frequent requirement for precision measurement skills. Technicians also need to inspect for hidden damage to components caused by failures not easily visible, such as components that are warped, twisted, or bent. Precision inspection tools are used in these instances, and technicians should know how to select and use the appropriate instruments.

FIGURE 05-2: Adjusting valve clearances and injector plunger travel are service procedures requiring precision measurement techniques.

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