TM 10-3930-653-14&P Prescribed clear- 0.025 to 0.045 ance (0.0010 to 0.0018) mm (in) [20°C (68°F)] Feeler gauge pulling force 0.5 to 1.5 kg (lb) (1.1 to 3.3) Feeler gauge thickness 0.04 (0.0016) mm (in) (6)   Cylinder liner If cylinder bore exceeds standard size by more than 1.5 mm (0.059 in), apply a cylinder liner.  Use a standard size piston and hone for proper fit. Measure outside diameter of liner (at top, middle and bottom) and hone cylinder bore for fit [oversize of 0.005 to    0.085    mm    (0.0002    to    0.0033    in)]    based    upon maximum  measure-ment  value.    Liners  are  removed  in direction   of   cylinder   head.      When   difficult   to   remove, remove with a press. Outer diameter Inner diameter Size Mark mm (in) mm (in) 40 91.20 to 91.25 (3.5905 to 3.5925) 45 91.70 to 91.75 86.70 to 86.80 (3.6102 to 3.6122) (3.413 to 3.417) 50 92.20 to 92.25 (3.6299 to 3.6319) 4-2-4-7. PISTON, PISTON PIN, AND PISTON RINGS (1)   MEASURING PISTON WEAR (1)   Inspect  piston  thrust  surface  for  binding,  scratches, or scars, and replace if excessively damaged or faulty. Fig. 4-51.  Checking Ring Grooves (2)   Measure piston ring to piston groove (land) clearance.    For  this  measurement,  install  a  new  ring  on piston  and  measure  with  a  feeler  (thickness)  gauge.    If clearance  exceeds  pres-cribed  limits,  replace  rings  (or piston) as required. Standard mm (in) Limit mm (in) Piston Top 0.040 to 0.073 ring-to- (0.0016 to 0.0029) 0.1(0.0039) groove Second 0.030 to 0.063 (land) (0.0012 to 0.0025) 0.1 (0.0039) clear- Oil 0.03 to 0.08 ance- (0.0012 to 0.0031) 0.2 (0.0079) (3)   Difference  in  weight  between  piston  assemblies  for individual cylinders should be within 2 grams (0.0705 oz). (2)   PISTON RINGS (1)   Piston ring end gap To measure piston ring end gap, apply piston ring to part   of   piston   skirt   where   cylinder   wear   is   minimum, invert piston and, after assuring that piston and ring  are positioned at right angles to cylinder, depress piston. Measure piston ring end gap with a thickness gauge and   replace   piston   ring   with   a   new   ring   if   end   gap measurement  exceeds  I  mm  (0.0394  in).    If  end  gap  is less than 0.15 mm (0.0059 in), either correct by applying an  oil  stone  to  grind  down  ends  of  ring,  or  replace  ring with a new ring. (2)   Measuring piston ring contracting force. Measure contracting force with a ring tester.  If load required to contact gap is below specified value, replace ring. 4 - 32