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Page Title: INSPECTION (cont)
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TM5-4210-229-14&P 6-12.  PISTON AND CONNECTING ROD MAINTENANCE (Continued). (1) Running clearance check (using virgin lead wire). (a) Remove bearing cap, then clean and oil the crankshaft journal. (b) Place a suitable length of 0.010 in (0.254 mm) virgin lead wire across the bearing then install the bearing cap, torquing nuts to 115 ft-lb (155 N.m). (c) After torquing nuts, remove them along with the bearing cap. (d) Remove the virgin lead wire which will have been crushed down to the amount of clearance between the crankshaft journal and the connecting rod bearing. (e) Measure the crushed wire with a micrometer to determine running clearance. (2) Running clearance check (using plastigage). (a) Remove bearing cap, then clean the bearing surface and exposed half of the crankshaft keeping them free of oil. (Plastigage is soluble in oil). (b) Place a piece of plastigage (Appendix D, Item 40a) across the bearing then install the bearing cap, torquing nuts to 115 ft-lb (155 N.m). (c) After torquing nuts, remove them along with the bearing cap. (d) The flattened plastic material will be found adhering to either the bearing shell or the crankshaft.  Do not remove the Plastigage. (e) To determine the running clearance, compare the width of the flattened plastic material at its widest point with the graduated marks on the envelope. The number within the graduation on the envelope indicates the clearance in thousandths of an inch. (3) Running clearance check procedure. (a) The measurement should fall within 0.0018 to 0.0051 in (0.046 to 0.130 mm).  Remove the test material and re- install the cap and bearing with correct torque if running clearance specifica- tions are met. (b) Repeat the chosen method of testing for all the remaining connecting rods. (c) If the measurements are not within the specified limits, and the torque wrench is known to be accurate, remove the bearing from the connecting rod and replace it with a new bearing. (4) Check connecting rod end clearance, using a feeler gauge.  Maximum permissible bear- ing end clearance on crankshaft is 0.018 in (0.46 mm). (a) The feeler gauge must cover both the connecting rod and cap. (b) Excessive clearance may require re- placement of the rods or shaft. (c) The check must be made to be certain that the specified clearance exits. (d) Lack of clearance could indicate a damaged rod or perhaps a rod bearing out of position. c.  Pistons and rings inspection. (1) Soak the piston and piston pin in soap solu- tion (until carbon is soft) and  clean thoroughly. 6-31

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