Chevrolet 70 Series 1970, Service Manual

Page: 448 / 841

53 AND 71 SERIES DIESEL ENGINES 6C-51
Figure 3—Inspection for Broken or Stuck Piston Rings ITypicalI
When an engine is run out of fuel inadvertently,
th ere is a definite procedure to follow for r e sta r t­
ing the engine. The procedure is outlined below:
1. F ill the fuel tank with the recom m ended
grade of fuel o il. If only partial fillin g of the tank is
p o ssib le , add a m inim um of ten gallons of fu el.
2. Rem ove the prim ary fuel strain er sh ell and
elem ent from the str a in er cover and f ill the sh ell
with fuel o il. In stall the sh e ll and elem ent.
3. R em ove and fill the secondary fuel filte r
sh e ll and elem ent with fuel o il as in Step 2.
4. Start the engine. C heckthe filte r and stra in ­
er for lea k s.
NOTE: In som e in sta n ces, it may be n e c e ssa r y
to rem ove a valve rock er cover and loosen a fuel
pipe nut in order to bleed trapped air from the fuel
s y ste m . B e su r e the fuel pipe is retightened s e ­
cu rely before replacing the rocker cover.
P r im e r (J-5956) may be used to p rim e the
en tire fuel sy ste m . R em ove the filte r plug in the
fu el filte r cover and in sta ll the p rim er. P rim e the
s y ste m . Rem ove the p r im er and in sta ll the filte r
plug.
FUEL FLOW TEST (F ig. 4)
1. D isconnect the fuel return tube and hold
the open end in a suitable container.
2. Start and run the engine at approxim ately
1 2 0 0
rpm and m easu re the fuel flow from the r e ­
turn tube for one m inute.
NOTE: At le a st
.6
gallon s of fuel on 53 S e r ie s
and .9 gallons on 71 S e r ie s engine should flow
from the return lin e p er minute.
3. B e su re a ll lin e connections betw een the
fu el supply and the pump a re tight so no a ir w ill be
drawn into the fuel system ; then, im m e r se the end
of the fu el return line into the fuel in the container.
Figure 4 —Fuel Flow Test
A ir bubbles risin g to the su rface of the fuel w ill
indicate a leak on the suction sid e of the pump.
FUEL QUALITY
The quality of the fuel o il used for d ie se l en­
gine operation is a m ajor factor in satisfactory
engine perform ance and life . The fu el o ils se le c te d
m ust be clean, com pletely d istilled , stab le, and
n o n -co rro siv e. E n list the aid of your supplier in
obtaining proper fuel o il. The resp on sib ility for
clean fuel lin e s with the fuel supplier a s w ell as
with the operator.
DISTILLATION RANGE, CETANE NUMBER,
AND SULFUR CONTENT a r e three of the m ost
important p ro p erties in the se le c tio n of d ie se l
fu els for optimum com bustion and minimum w ear.
Engine speed, load, and atm ospheric tem perature
influence the se le c tio n of the fu els with r e sp ect to
d istillation range and cetane num ber. THE SUL­
FUR CONTENT OF THE FUEL MUST BE AS LOW
AS POSSIBLE, to avoid e x c e s s iv e deposit form ation
and prem ature w ear.
FUEL PRESSURE TEST
The fuel p r e ssu r e gauge is designed for u se in
checking fuel p r e ssu r e at the in jector with the
engine in operation. R em ove the jumper lin e from
the in jector to the return fuel manifold and connect
the fuel gauge in p la ce of the jumper line (fig. 5).
R efer to "Fuel P r e ssu r e " chart following:
FUEL PRESSURE
Engine
SPEED (RPM)
1 2 0 0
1800
2 1 0 0 2 2 0 0
2600
6V-53
6-71
8V-71
30-65
45-70
45-70
45-70 45-70
45-70
45-70 45-70
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL