TM 5-3895-383-24 4. Fuel has a high "Cloud Point": The fuel "Cloud Point" is the temperature at which wax begins to form in the fuel.  If the atmospheric temperature  is  lower  than  the  "Cloud  Point"  of  the fuel, wax will form and plug the fuel filter.  Change the  filter  and  drain  the  fuel  tank  and  the  complete fuel system.  Replace the fuel with a better grade of fuel with a lower "Cloud Point". 5. Defect in fuel injector(s): a. Temperature of an exhaust manifold port, when the engine runs at low idle speed, can be an indication of the condition of a fuel injector.  Low temperature at  an  exhaust  manifold  port  is  an  indication  of  no fuel   to   the   cylinder.      This   can   possible   be   an indication  of  an  injector  with  a  defect.    Extra  high temperature at an exhaust manifold port can be an indication  of  too  much  fuel  to  the  cylinder,  also caused by an injector with a defect.  NOTE:    Only experienced mechanics should use this technique.        There    can    be    wide    operating temperature variations on the exhaust manifold and     the     injectors     can     still     be     operating correctly. b. Check the height of all injectors to make sure there are no seized injectors. c. Check for free travel of all injector rack bars. d. If an injector is suspected to be defective, check the injector.    Use  the  1U6661  Pop  (injector)  Tester  to check  the  injector  for  proper  operation.    Refer  to Special     Instruction,     SEHS8867     for     additional information. 6. Valve adjustment not correct: Check  and  make  necessary  adjustments  as  per Testing    and    Adjusting    Section    of    the    Service Manual.  Intake valve lash is 0.38 mm (.015 in) and exhaust  valve  lash  is  0.64  mm  (.025  in).    Also check for a bent or broken push rod. 7. Fuel injection timing not correct: Check  and  make  necessary  adjustments  as  per Testing    and    Adjusting    Section    of    the    Service Manual. 8. Bent or broken push rod: Check   injectors   height   for   any   seized   injectors and/or bent or broken pushrods.  Replace pushrods as necessary. 9. Fuel injector control linkage binding: Disconnect the governor output shaft from the fuel injector   control   linkage.      Check   the   linkage   for smooth  operation.    If  linkage  still  appears  to  be binding,  remove  injectors.    With  injector  springs compressed,    check    injector    racks    for    smooth operation.  Replace injectors with "sticky" racks. Check  linkage  again  for  smooth  operation.    If  still  binding, loosen  bolts  holding  linkage  to  cylinder  head.    Operate  the linkage by hand.  If binding is still present after retightening the bolts, replace the control linkage. 10. Cylinder head gasket leakage: Leakage at the gasket of the cylinder head can show as  an  outside  leak  or  can  cause  loss  of  coolant through  the  radiator  overflow.    Remove  the  radiator cap and with the engine running look for air bubbles in the coolant.  Bubbles in the coolant are a sign of probable  leakage  at  the  head  gasket.    Remove  the cylinder  head  from  the  engine.    Check  the  cylinder head, cylinder walls and head gasket surface of the cylinder block for cracks.  When installing the head, use a new head gasket.  Tighten the bolts that hold the   cylinder   head   according   to   the   Specifications Section of the Service Manual. 11. Valve  leakage;  wear  or  damage  to  pistons  and/or  piston rings; wear or damage to cylinder walls:  If leakage is heard at the inlet manifold, the intake valves leak.  If the leakage is heard  at  the  exhaust  manifold,  the  exhaust  valves  leak. Pistons or rings that have damage can be the cause of too much pressure in the crankcase.  This condition can cause ore than the normal amount of fumes (blow-by) coming from the crankcase breather.  The 8T2700 Indicator Group is used to check the amount of blow-by.  The test procedure is in Special Instruction, SEHS8712. 12. Improper injector synchronization: Check  and  make  necessary  adjustments  as  per Testing    and    Adjusting    Section    of    the    Service Manual. 13. Low idle rpm: Check  and  make  necessary  adjustments  as  per testing and adjusting section of this service manual. 14. Governor control group linkage: Check  and  make  necessary  adjustments  as  per Testing    and    Adjusting    Section    of    this    Service Manual. 15. Loose or missing dash pot orifice plug: Remove   the   cover   at   the   rear   of   the   governor. Replace or tighten the orifice plug with new locking plug. 6-35