TM  10-3930-638-24&P 3-3. ENGINE TROUBLESHOOTING (cont) MALFUNCTION TEST OR INSPECTION CORRECTIVE  ACTION 7.  ENGINE  COMPRESSION  TEST  (cont) a. b. c . d. If compression is high, remove cylinder head and check for carbon deposits on cylinder head and piston crown (para 3-5g). Also, check (use micrometer) if too much material was removed from resurfaced cylinder head (cylinder head minimum thickness is 3.968 inches) (notify  general  support  maintenance)  (para  4-2b). If compression is low, squirt a teaspoon of engine oil into the affected cylinder and repeat compression  test.  If  compression  gage  reading  increases  to  near  normal,  remove  cylinder  head (para 3-5g) and check piston rings and sleeves (notify general support maintenance) (para 4-2f and  4-2a). If  compression  gage  reading  remains  low  after  squirting  oil  in  cylinder,  remove  cylinder  head (para 3-5g) and check for blown head gasket. If gasket is not damaged, check for burned or damaged  valves  and  valve  seats  (notify  general  support  maintenance)  (para  4-2b). If compression is low, and items in steps b and c above check satisfactorily, check for head gasket  leakage  due  to  excessive  piston  sleeve  protrusion  (notify  general  support  maintenance) (para  4-2a). 3-4. FUEL SYSTEM TROUBLESHOOTING MALFUNCTION TEST OR INSPECTION CORRECTIVE  ACTION 1.  ENGINE  IDLE  SPEED  INCORRECT Perform fuel injection pump timing and idle speed adjustments (para 3-5a(3)). a. b. If idle speed screw on injection pump does not vary engine speed, replace fuel injection pump (para 3-6c). If idle speed screw on injection pump changes engine speed, but will not adjust to correct value,  check  accelerator  linkage  (para  2-15i).  If  accelerator  linkage  checks  satisfactory,  check fuel  pressure  (para  2-10)  and  fuel  injectors  (para  3-6b).  If  above  checks  are  satisfactory, replace  fuel  injection  pump  (para  3-6c). 2.  ENGINE  NO-LOAD  GOVERNED  SPEED  INCORRECT Perform fuel injection pump timing and no-load governed speed adjustments (para 3-5a(3)). a. If high speed screw on injection pump does not vary engine speed, replace fuel injection pump (para  3-6c). b. If high speed screw on injection pump varies engine speed, but will not reduce speed to correct value (no-load speed too high), replace fuel injection pump (para 3-6c). c. If high speed screw on injection pump varies engine speed, but will not increase speed to correct value (no-load speed too low), check accelerator linkage (para 2-15i), fuel pressure (para  2-10)  and  fuel  injectors  para  3-6b).  If  above  checks  are  satisfactory,  replace  fuel  injection pump  (para  3-6c). 3 - 6