Figure 3-4.–Liner before and after stoning.types of liner wear check are illustrated in figure 3-5.Excessive maximum diameter results from general wearequally around the cylinder. Out-of-roundness isproduced by the piston thrusting against one or two sidesof the cylinders.Clearance between a piston and a liner is generallychecked by measuring both parts with a micrometer. Onsmaller engines, you can use a feeler gauge. Clearancein excess of that specified by the manufacturer isgenerally due to liner wear, which normally is greaterthan piston wear.To determine liner wear, take measurements at threelevels in the liner. Take the first measurement slightlybelow the highest point to which the top ring travels;take the next measurement slightly above the lowestpoint of compression ring travel; and take the thirdmeasurement at a point about midway between the firsttwo. (Record all readings, so that rapid wear of anyparticular cylinder liner will be evident.) If wear orout-of-roundness exists beyond specified limits, replacethe liner. Figure 3-6 shows two examples of takingFigure 3-5.–Measurements for determining liner wear.Figure 3-6.–Measuring the inside of a cylinder liner.inside measurements. The liner shown in figure 3-6,view B, requires at least twice as many measurementsas other types of liners because it is from an opposedpiston.You will not get accurate measurements unless youposition the caliper or gauge properly in the liner.Common errors in positioning are illustrated in views Aand B of figure 3-7. Hold one end of the caliper firmlyagainst the liner wall as shown in view A of figure 3-6.Then move the free end back and forth, and up anddown, until you establish the true diameter of the liner.The moving end will trace a patch similar to thatillustrated in figure 3-8.Considerable experience in using an insidemicrometer or cylinder gauge is necessary to ensureaccuracy. As a precaution against error, it is a good3-5
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business