TM  10-3930-643-34 GENERAL  SUPPORT  ENGINE,  FUEL,  EXHAUST  AND  COOLING  MAINTENANCE.  (cont) 13-3 l Crankcase and Cylinder Sleeves. (Sheet 5 of 11) CLEANING/INSPECTION   (cont) 14. Clean crankcase and seven caps (3) with  cleaning solvent P-D-680. Remove  all  carbon  and  mineral deposits. Clean all passages, ports and holes. Dry thoroughly with compressed air. If cleaning solvent P-D-680 fails to remove scale, send crankcase  to  Depot  Maintenance. 15. Clean all other parts with cleaning solvent  P-D-680. Dry  thoroughly  with compressed air. Refer to paragraph Do not resurface the crankcase. Damage  and  defects  not  correctable by  light  filing indicates replacement  is  needed. Damaged crankcase must be sent to Depot Maintenance   to determine salvageability. 16. Check deck of crankcase for “pulled” thread holes. Lightly file area to restore  flatness. 17. Inspect threaded holes. Threads may be  retapped  or  repaired  with heli-coils,  if  necessary. Go to sheet 6 13-18