4. DISASSEMBLY, INSPECTION AND REASSEMBLY OF ENGINES (4) Piston Especially clean the combustion surface, cir- cumference, ring grooves and piston pin bosses, and check after removing any carbon deposit. Any burr at a ring groove or snap ring groove shall be removed. If crack is suspected, inspect by color check. (a) Piston outside diameter measurement Measure the long diameter at H mm from the bottom end of the piston of the oval hole in the vertical direction to the piston pin hole. Piston outside diameter mm If the piston outside diameter exceed the limit, replace the piston with new one. If necessary, use an oversized piston.
(Refer to the tables of oversized pistons, oversized piston rings and cylinder boring dimension in (1)(c) above.) Selective pairing of cylinder and piston Piston must be paired with cylinder according to the below table. The size mark of a piston is shown on the top surface of the piston and the size mark of a cylinder block is shown on the non-operating side of the cylinder block. The service parts of pistons are provided.
4-44 82E-5 – 98E-5 SERIES Model Outside diameter Standard Limit Clearance between piston and cylinder Measurement position (H) 3D82AE 81.950 – 81.980 81.905 0.035 – 0.065 16 (S)3D84E, (S)4D84E 83.940 – 83.970 83.895 0.045 – 0.075 24 3D88E, 4D88E 87.940 – 87.970 87.895 24 4D94LE 93.935 – 93.965 93.890 0.050 – 0.085 22 (S)4D98E 97.930 – 97.960 97.885 0.055 – 0.085 22 Tolerance Size mark Piston outside diameter. D2 Tolerance +0.015 max. +0.005 min. below +0.005 0 min. below 0 –0.005 min. below –0.005 –0.015 min. Size mark L ML MS S Cylinder inside diameter D1 +0.030 max. +0.020 min. L Q Q X X below +0.020 +0.010 min. M X Q Q X below +0.010 0 min.
S X X Q Q Model Cylinder inside diameter D1 Piston outside diameter D2 3D82AE 82 81.965 (S)3D84E, (S)4D84E 84 83.955 3D88E, 4D88E 88 87.955 4D94LE 94 93.950 (S)4D98E 98 97.945