TM   5-2815-241-34&P TROUBLESHOOTING  ON  ENGINE  TEST  STAND  –  CONTINUED MALFUNCTION TEST  OR  INSPECTION CORRECTIVE  ACTION 18. EXCESSIVE  WHITE  SMOKE  AT  IDLE  –  CONTINUED. Step  5. Check  valve  adjustment  (page  2-106). Readjust   valves. Step  6. Remove  injectors  (page  2-34).  Check  for  correct  injector  cup  size (page  2-289). Replace  incorrect  injector  cups. 19. FUEL  KNOCKS  (COMBUSTION  NOISE). Step  1. Check  for  starting  fluid  build  up  in  intake  manifold. Remove built up starting fluid. Step  2. Check for excess fuel in intake manifold from starting aid. Repair  starting  aid  (page  2-289)  and  remove  excess  fuel. Step 3. Check  filter,  gaskets,  connections,  and  suction  lines  for  air  leaks. Replace  defective  filter,  leaking  gaskets,  connections,  and  lines. Step  4. Check  for  low  coolant  temperature  or  defective  thermostat. Replace  defective  thermostat. Step  5. Check  injector  timing  (page  2-106). Reset  injector  timing. Step  6. Check  valve  adjustment  (page  2-106). Readjust   valves. Step  7. Remove  injectors  (page  2-34).  Check  for  damaged  preformed  packings (page  2-289). Replace   damaged   packings. 20. LOW OIL PRESSURE. Step  1. Check crankcase oil level. Refill to proper level. Step  2. Check  oil  suction  line  for  restrictions. Repair or replace restricted line. Step  3. Check  for  high  engine  temperature  or  defective  thermostat. a. Replace defective thermostat. b. Refill coolant to proper level. Step  4. Check  bypass  filter  orifice  for  correct  size  (page  2-264). Replace orifice with correct size. Step  5. Check  for  correct  main  and  connecting  rod  bearing  clearance  (page  2-214). Replace  bearings  with  proper  size.  Repair  crankshaft. Step  6. Check  for  main  and  connecting  rod  bearing  damage  (page  2-214). a. Repair  cause  of  damage. b. Replace  damaged  main  and  connecting  rod  bearing.  Repair crankshaft. 2-432