TM   10-3930-643-20 ENGINE, FUEL, EXHAUST AND COOLING TROUBLESHOOTING AND MAINTENANCE. 4-5. Exhaust   System   Troubleshooting. MALFUNCTION TEST OR INSPECTION CORRECTIVE   ACTION b. EXCESSIVE  WHITE  OR  BLUE  SMOKE. Check   operating   temperature   of   coolant   on   instrument   panel   gage. Allow  engine  to  warm  up. If   engine   does   not   reach   operating   temperature,   go   to   Cooling   System Troubleshooting. If   problem   continues,   notify   Direct   Support. c.   NOISY   EXHAUST. Check   for   loose   or   broken   exhaust   pipe   connections,   faulty   muffler   or missing   clamps. Replace   if   necessary. Refer   to   paragraph   4-26. If   problem   continues,   notify   Direct   Support. d. LOUD WHINE OR METALLIC SCREAM. Immediately   stop   engine.   Whine   and   scream   sounds   indicate turbocharger problems. Notify   Direct   Support. 4-17