Piston Selection Figures 12-34 and 12-35 1 . Check the used piston to cylinder bore clearance. Measure A . Cylinder bore diameter. Use a telescoping bore gage, located 65 mm (2.5 in.) below the top of the cylinder bore (figure 12-34). Piston Assembly Assembling the Piston and Connecting Rod Figure 12-36 Tool Required: J 24086-B Piston Pin Remover and Installer Set Install or Connect 1 . Piston and connecting rod. A . The valve cutouts in the piston crown must be opposite the connecting rod bearing tangs. B. Lubricate the piston pin holes in the piston and connecting rod with engine oil. C. Install the pin guide to hold the piston and connecting rod together.
Be sure to use the proper pin guide. Refer to the instructions supplied with the tool. Figure 12-34 Measuring Cylinder Bore Diameter B . Piston diameter. Measure the piston skirt at a right angle to the piston pin, at the centerline of the piston pin (figure 12-35). C . Subtract the piston diameter from the cylinder bore diameter to determine piston to bore clearance. D . Refer to “Specifications” in the proper Section. Determine if the piston clearance is in the acceptable range. 2 . If the used piston is not acceptable, determine if a new piston will fit the cylinder bore. 3 . If a new piston does not bring the clearance within tolerances, the cylinder bore must be reconditioned. 4 .
Mark the piston to identify the cylinder for which it was fitted. Figure 12-36 Installing Piston Pin 2 . Piston pin. A . Insert the piston pin into the piston pin hole. B . Place the assembly on the support fixture. Figure 12-35 Measuring Piston Skirt G643 (E) Service Manual Chapter 3. Engine Mechanical System 78