TM 5-3895-383-24 Problem 14:  Oil In Cooling System Probable Cause(s): Defect In Core Of Engine Oil Cooler Failure Of Cylinder Head Gasket 1. Defect in core of engine oil cooler: Inspect  cooler  and  make  a  replacement  or  repair defective    oil    cooler.        Flush    cooling    system    to remove oil. 2. Failure of cylinder head gasket: 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. Problem 15:  Mechanical Noise (Knock) In Engine Probable Cause(s) Failure Of Bearings For Connecting Rod Damaged Gears Damaged Crankshaft Defect In Accessory Equipment Damaged Injector Rocker Arm, Missing Insert, Or Broken Socket 1. Failure of bearings for connecting rod: Inspect  the  bearings  for  the  connecting  rods  and the  bearing  surfaces  (journals)  on  the  crankshaft. Install new parts where necessary. 2. Damaged gears: Install new parts where necessary. 3. Damaged crankshaft: Make replacement of the crankshaft. 4. Defect in accessory equipment: Repair as needed or install new components. 5. Damaged injector rocker arm, missing insert, or broken socket: Repair as needed or install new components. Problem 16:  Fuel Consumption Too High Probable Cause(s): Fuel System Leaks Fuel Setting Too High Fuel And Combustion Noise (Knock) Incorrect Fuel Timing Dimension Defect In Fuel Injector(s) 1. Fuel system leaks: a. Check fuel system for any external leaks.  Check all lines,  hoses,  and  fittings  for  leaks  and  tighten  or replace as necessary. b. Check for a defective O-ring seal on the top of the injector.  Remove the fuel supply line at the rear of the cylinder head and pressurize the cylinder head (the return to fuel tank line will have to be blocked). Look for fuel leaking from the injectors where they seal with the cylinder head.  If fuel is leaking from an   injector,   remove   the   injector   and   replace   the upper O-ring seal.  Also depending on the amount of   leakage   an   oil   sample   should   be   taken   and checked for fuel dilution.  Change oil and oil filter if necessary.  While the cylinder head is pressurized, check for porosity around the oil drain back holes. If  porosity  is  found,  replace  the  cylinder  head.    If fuel is found in the coolant then check the injector sleeves in the cylinder head for cracks or erosion. If defects are found, then remove the sleeves and install new sleeves. 2. Fuel setting too high: Check   and   make   necessary   adjustments   as   per Testing    and    Adjusting    Section    of    the    Service Manual. 3. Fuel and combustion noise (knock): See  Problem  No.  4,  Misfiring  and  Running  Rough. See Problem No. 12, Loud Combustion Noise. 4. Incorrect fuel injection timing dimension: Check   and   make   necessary   adjustments   as   per Testing    and    Adjusting    Section    of    the    Service Manual. 5. Defect in fuel injectors: Use the 1U6661 Pop (Injector) Tester to check the injectors   for   proper   operation.      Refer   to   Special Instruction, SEHS8867 for additional information. 6-41