TM    5-3895-369-14 Table  4-2.  Unit  Preventive  Maintenance  Checks  and  Services MO - Months Item Interval No. MO Hr Item  to  Be Inspected Hr - Hours Procedure ENGINE 1 3 250 Engine Change  the  lube  oil  and  filter  (paras  4-24  and  4-35).  Refer  to crankcase Chapter 3, Section I. 2 6 500 Fuel  filters Change  fuel  filters  (para  4-52).  Bleed  fuel  system  if required  (para  4-54). 3 12 1000 Valves Adjust  valve  lash  clearance  (para  4-30): Intake - 0.010 in. (0.254 mm) Exhaust - 0.020 in. (0.508 mm) 4 6 500 Radiator Check the anti-freeze concentration. Add enough anti-freeze to protect  the  engine  to  -24°F  (-31°C)  (para  3-7). 5 12 1000 Cooling  system Drain  the  cooling  system  (para  4-66).  Check  for  damaged  hoses,  and loose or damaged hose clamps. Replace as required (para 4-62). Check radiator for leaks, damage, and build-up of dirt. Clean and repair as required (para 4-60). Flush the system until the water is clean. Use a mixture of 50% water and 50% anti-freeze. System capacity  is  6  gal.  (23  I). 6 12 1000 Drive  belt, Check the belt deflection at the longest span of belt. Maximum tensioner deflection is 5/8 to 1/2 in. (9.5 - 12.7 mm). Replace belt if required bearing, and fan (4-68). Check the tensioner and fan hub bearings. Should spin freely hub with no rough spots, wobble, or end play. Replace tensioner or fan hub if required (paras 4-69 and 4-67). 7 24 2000 Vibration Check the index lines on the damper hub and the inertia member. If damper the lines are more than 1/16 in. (1.59 mm) out of alignment, notify direct support maintenance. If NBC exposure is suspected, all air filter media should be  handled  by  personnel  wearing  protective  equipment. Consult  your  unit  NBC  Officer  or  NBC  NCO  for appropriate handling or disposal procedures. 8 3 250 Air cleaner/ Check/inspect air cleaner element (para 3-8). Tighten or replace intake  system parts as necessary to make sure air intake system does not leak (i.e. cracked  hoses,  loose  clamps,  punctures,  etc.). 4-10