TM 10-3930-671-24 Alternator Installation Figure 4.  V-Belt Tensioning Alternator Drive (Fan) Belt 1. Inspect fan belt and pulleys for damage. 2. Fan  belt  must  not  have  any  cracks  or  contact bottom of pulley grooves. 3. Be sure there is no oil on fan belt. 4. Fan   belt   worn,   oily   or   damaged:      Clean   or replace as necessary. 5. Fan     belt     adjustment     not     OK:          Adjust     as necessary. Fan Belt Tensioning NOTE Particular  attention  should  be  paid  to  V-belt  tension,  as slipping  belts  are  the  cause  of  many  other  problems  in accessory drives as well as in the charging system.  Low belt tension can induce slipping, with resultant excessive belt    and    pulley    wear,    and    overheating    of    the    front alternator bearing. A  slipping  belt  will  not  drive  the  alternator  to  full  output, eventually leading to battery discharge problems. A   belt   which   has   been   slipping   will   be   glazed   and cracked.  Such a belt should be replaced. Excessive  belt  tension  will  create  an  overload  condition in    the    alternator    front    bearing    and    in    water    pump bearings. Fan Belt Tension Specification Adjust  belt  tension  to  2.5-3.2  lb-ft.    (11.1-14.2  N)  .20  in (5.2 mm) deflection at midpoint of span. 1. The    fan    belt    is    tensioned    by    adjusting    the alternator. 2. Loosen bolt at alternator adjusting  strap,  tighten belt as required, and retighten bolt. CAUTION When    tensioning    fan    belt,    tighten drive belt by applying pressure to the alternator   front   housing   only.      DO NOT     apply     pressure     to     the     rear housing or stator. NOTE New    belts    will    lose    a    substantial amount  of  the  original  tension  in  the first   few   hours   of   operation   as   the belt seats into the pulleys and should be retensioned accordingly. F-264