TM  5-2815-241-34&P PISTON AND CONNECTING ROD - CONTINUED ACTION LOCATION ITEM REMARKS ASSEMBLY CAUTION Pistons are machined to a very close weight tolerance. Make sure the same part number piston  is  used  throughout  the  engine.  Weight  difference  will  affect  engine  operation. 42. Piston (1) Retaining  ring  (2) Using 6-inch snapring pliers, put in groove in piston bore. Heat-protective cloth mittens must be worn to prevent serious injury to hands when handling  heated  parts. CAUTION Pistons must be heated in hot water to prevent piston damage during piston pin installation. Do not drive piston pins with hammer. Driving may cause distortion of piston, causing piston seizure in cylinder sleeve. Be sure retaining ring is firmly seated in groove of piston pin bore to prevent serious engine  damage. Do not attempt to push in piston pin after piston has cooled. At 70°F (21°C), the piston pin  fit  is  0.0001  to  -  0.0003  inch  (0.003  to  - 0.008 mm), which prevents piston pin assembly  unless  piston  is  heated. NOTE Install  new  or  inspection-approved  pistons  on  connecting  rod.  Be  sure  to  install  pistons on  their  companion  connecting  rod,  as  tagged  during  disassembly. 43. Piston  pin  (3)  and retaining  ring  (4) a. Submerge  in  container  of  boiling  water for 15 minutes to allow pistons to expand. b. Remove from boiling water and place connecting  rod  in  piston. c. Push  piston  pin  through  piston  pin  bore (5)  and  connecting  rod  bore  before  pis- ton  cools. d. Using 6-inch snapring pliers, put retaining ring in groove in piston pin bore  (5). 2-236