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TRUCK SERVICE MANUAL
TM 5-4210-230-14&P-1
FUEL SYSTEM
After  servicing  filter  element,  reset  signal  (red  band)  by
pressing reset button and then releasing.  This allows red signal
band to again rise above window.
Where a direct reading air cleaner restriction gauge (Fig.
10) is used, the maximum allowable restriction is 25 inches of
water  measured  at  the  air  cleaner  outlet  during  any  phase  of
engine operation.  When this happens, filter element service is
required.
Fig.  10  Air Cleaner Restriction Gauge
SERVICING
NOTE:    Refer    to    the    applicable    owner's    manual    to    obtain
recommended     mileage     intervals     for     air     cleaner     element
replacement and service.
Modulated Dry Type Air Cleaner
Service of modulated dry type air cleaner paper element
is    limited,    consisting    mainly    of    checking    the    element    for
punctures   or   splits   by   looking   through   element   toward   light.
Tap element-lightly on a flat surface or use low air pressure to
remove dirt particles.  Do not wash or oil element.
Operation   of   the   vacuum   chamber   and   temperature
sensor may be checked by conducting the following tests.
NOTE:  Tests  should  be  conducted  with  engine  started
from  cold  and  ambient  temperature  of  vehicle  being  not
less than 40    F.  Air cleaner must have all hoses, piping
and cover in place.  No leaks permitted.
1.
With  engine  off  inlet  tube  damper  should  be  in  full
down   position   to   close   heat   tube   inlet   pipe   from
exhaust   manifold   stove.      Damper   position   can   be
determined  by  looking  in  end  of  inlet  tube  and  should
be parallel to tube bottom.  If damper assembly is not
in   the   correct   position,   vacuum   chamber   should   be
removed  and  damper  movement  loosened.    Replace
vacuum chamber and recheck damper position.
2.
Start  engine  and  note  that  damper  has  rotated  up  to
close  off  cold  air  inlet.    Observe  damper  position  by
looking in the inlet tube.  If damper did not immediately
close cold air inlet, shut off engine and disconnect the
two  hoses  from  sensor.    Connect  the  two  hose  ends
together using suitable tubing.
Restart  engine  and  again  check  damper  location.    If
damper  fully  closes  cold  air  inlet,  temperature  sensor
is  defective  and  must  be  replaced.    If  damper  did  not
close cold air inlet, sensor is okay but damper has bind
or   vacuum   chamber   is   defective.      Remove   vacuum
chamber   and   check   damper   for   free   movement.      If
damper moves freely, replace vacuum chamber.
3.
After   a   cold   start   operate   engine   for   10   minutes   at
medium  RPM.    When  engine  is  at  normal  operating
temperature,  slow  engine  to  idle  and  observe  position
of inlet tube damper.  If damper has not rotated all or
part  way  down  to  allow  some  cold  air  to  enter  inlet
tube, replace temperature sensor.
Vacuum Chamber Replacement (Fig. 11)
Vacuum   chamber   is   replaced   by   bending   tab   nearest
inlet   tube   entrance   down   from   inside   of   tube.      Disconnect
vacuum  hose  and  lift  vacuum  chamber,  sliding  rear  tab  out  of
its slot and disengaging damper hook from damper.
The   new   chamber   is   attached   by   engaging   hook   in
damper,  sliding  rear  tab  into  its  slot  and  fitting  front  tab  into
place.  A spring preload should be felt when vacuum chamber is
pressed  firmly  against  top  of  inlet  tube.    If  no  preload  is  felt,
check the installation or   
CTS-2056N  Page 5
PRINTED IN UNITED STATES OF AMERICA
 
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