The cylinder liner should be measured in planes parallel and at right angles to the crankshaft. Wipe the interior of liner clean before measuring bore, and check for physical defects that would require rework on the liner. A liner bore gauge, Fig. 45, or standard inside micrometers may be used to measure liner bore diameter. The gauge is of a special design for liner bore measurement, and will provide accurate measurement when used carefully. It has a three-pronged centering and measuring end that fits the liner bore. A dial indicator, mounted on an upright that extends down to the measuring prongs, gives instant reading of bore diameter. The upright allows the gauge to be raised and lowered in the bore with visual measurement shown on the dial. A master gauge is used to calibrate the bore gauge.
A dial gauge locator should be used with the liner bore gauge. The gauge locator fits over the top of the liner and hangs down inside the liner bore. It has four 12.7 mm (1/2") drilled holes spaced at 50.8 mm (2"), 152.40 mm (6"), 304.8 mm (12"), and 406.40 mm (16") from the top to locate the measurement position.
A special box to protect the liner bore gauge also provides a place for the master gauge and the gauge locator.
NOTE: Dimensional wear limits are listed in Service Data at the end of the section. New cylinder liners have a bore diameter which falls between a low and a high limit. The bore diameter at the port relief zone has different dimensional limits.
Accumulated liner and piston wear will increase piston to liner clearance and this clearance is a limiting factor at time of reapplication. No liner should be matched with a new or used piston where the diameters result in a piston to liner clearance exceeding the maximum limit, at a point 152.4 mm (6") inches below the gasket face of the liner.
The liner bore should be checked for out-ofround at two points 50.8 mm (2") and 152.4 mm (6") below top of liner, Fig. 4-6, using the dial gauge locator as a guide. Take two readings 90° apart to determine wear and out-of-round. Should the out-of-round exceed the limit, the liner must be rebored to the next oversize, regardless of other wear measurements which still may be within limits. Using the maximum piston to liner clearance as a guide, worn liners may be used again, providing they are not over out-of-round limit, and are matched with pistons having a diameter which will not exceed the limit on piston to liner clearance. Maximum piston and liner usage is obtained by selective assembly within the clearance limit.
Liners will wear tapered, with maximum wear normally occurring approximately 152.40 mm (6") below the top limit of piston ring travel. Check that wear, taking two readings 90° apart, is within specified limit. A liner worn to this dimension will leave some stock to allow for cleaning up the bore to the first oversize. If this limit is exceeded, it may not be possible to rebore liner to the first oversize. It would then have to be rebored to the next oversize, losing a great amount of its wear life. Consequently, it is suggested that no liner be reinstalled if the bore diameter at point of maximum wear exceeds the allowable limit.

After a long period of use, a wear ridge, caused by piston ring action, will appear near the top of the liner bore. After the liner is removed from the engine, the wear ridge must be entirely removed before honing the liner. Unless complete removal of the wear ridge is accomplished, it is not possible to properly hone the critical area of the liner at the top of the ring travel. In addition, removal of the wear ridge precludes any possi-bility of interference with new piston rings.
The cylinder liner ridge reamer, Fig. 47, is used to remove the ridge at the top inside bore of the liner. The reamer can also be used for the oversize liners. Reamers may either be manually or motor operated. If the reamer is motor operated, a speed reducer must be used, which is mounted on the reamer. The operating motor used with the speed reducer can be an ordinary heavy-duty electric drill having a no load speed of approximately 500 RPM.
Fig. 4-7 - Application Of Liner Ridge Reamer And Speed Reducer
Extra cutting blades may be obtained for reamers. Refer to Service Data at the end of this section.
Reamer cutting blades also may be resharpened. To resharpen a dull cutter, it is necessary only to lightly grind the leading angle which does the cutting, using a grinding wheel suitable for grinding tungsten carbide tools. The clearance angle is 8° and must not be exceeded when grinding. It is better to provide "less" than more clearance, as these cutters will not stand up if given greater clearance.
In addition, a cutter should not be used if the guide portion has been reduced to a length of 16.67 mm (21/32") by resharpening, because the guide will not extend far enough past the pin hole to prevent undercutting. For resharpening service on the cutters, refer to the reamer manufacturer.