(d) Slowly close restrictor valve while watching pressure gage and
p r e s s u r e relief valve hole in pump. Check that oil starts to squirt out of pressure
r e l i e f valve hole when pressure gage reads between 140 and 225 pounds per square
( e ) If oil does not start
to squirt out of pressure relief valve hole when
p r e s s u r e gage reads between 140 and
225 psi, stop test. Take apart pressure relief
v a l v e . Refer to para 4-17a, frame 4.
Add or take out shims shown in figure 4-3 to
change relief valve opening pressure.
Do steps (c) and (d) again.
Pressure Relief Valve Shims.
(2) Flow test.
P r e s s u r e relief adjustment must be done before
f l o w test. Refer to para 4-17e (1).
O i l pump has two halves. Front half of pump
b e h i n d drive shaft is called pressure pump.
R e a r half of pump is called scavenge pump.
( a ) If scavenge pump has not already been oiled, pour some engine
l u b r i c a t i n g oil into scavenge pump so scavenge pump impellers will not be damaged
d u r i n g test.
( b ) Hook oil pump to test bench as shown in figure 4-2.
( c ) Open pressure restrictor valve. Start drive unit, Run pump until
air is out of system and oil temperature holds steady at 200°F to 210°F for all engines
e x c e p t LDS-465-2 and 220°F to 240°F for engine LDS-465-2.
( d ) Work drive unit to speed up oil pump to 3,420 rpm. Slowly close
r e s t r i c t o r valve until pressure gage reads 110 psi.
( e ) For all engines except LDS-465-2, check that flow meter reads
2 2 gallons per minute (gpm) or more. If flow meter reads less than 22 gpm, get a
new oil pump.
( f ) For engine LDS-465-2, check that flow meter reads 26 gpm or more.
If flow meter reads less than 26 gpm, get a new oil pump.