Chevrolet 70 Series 1970, Service Manual

Page: 726 / 841

STEERING SYSTEM 9-47
8. Truck leads to one
side or to the other.
D ue to fro n t end m isalignm ent.
Un b alan c ed or b ad ly w orn valve.
N O TE:
If this is the cause, steering effort w ill be
very light in direction o f lead and heavy in o p p o ­
site direction.
A d ju s t to specification.
Replace valve.
9. Momentary in­
crease in effort
when turning
wheel fast.
Lo w oil level in pu m p .
Pu m p belt slipping.
C heck oil level in pu m p reservoir and bring to proper level.
Tigh ten or replace belt.
10. Excessive wheel
kick-back or loose
steering.
Lash in steering linkage.
A ir in the system .
Excessive lash between pitm an shaft sector and
ball n u t.
Loose th ru s t bearing a dju s tm e n t.
A d ju s t parts affected.
A d d oil to pu m p reservoir.
A d ju s t to specification.
Rem ove steering gear and ad ju s t to specification.
11. Steering wheel
surges or jerks
when turning with
engine
ru n n in g —
especially during
parking.
Loose pu m p belt.
A d ju s t to specification.
12. Hard steering
when parking.
Loose pu m p belt.
Lo w oil level in reservoir.
La ck of lubrication in linkage for fro n t suspension.
T ire s not prop erly inflated.
Insufficient oil pressure.
A d ju s t to specification.
Fill to proper level. If excessively low . check all lines and joints
for evidence of external leakage.
A d d lubricant w here needed as described in lubrication (S ec . 0 )
of this m anual.
Inflate to recom m ended pressure.
If all of the above checks do not reveal the cause of hard steering,
m ake the follo w in g tests of oil pres su re :
a. Disconnect the pressure line at oil p u m p . A tta ch gauge to p u m p .
Connect the hose to end of gauge w here the valve is located.
b. W ith the engine at w a rm idle and gauge valve op en , note the
oil pressure on the gauge w hile tu rn in g steering w heel from one
extrem e position to the oth e r. Especially note the m a xim u m
pressure w hich can be b u ilt up w ith the w heel held in either
right or left extre m e position . CAUTION : D o not hold w heel in
extrem e position fo r an extended period of tim e because it will
drastically increase the oil tem p eratu re and w ill cause un du e
w ear on the oil pu m p .
c. W ith oil tem p eratu re betw een 150 degrees F and 1 70 degrees
F , as m easured w ith a th e rm o m e te r in the rese rvoir, th e m a x i­
m um oil pressure should not be less th an 600 P S I fo r sa tis­
factory pow er steering op eration .
d . If the m a xim u m oil pressure is less than 600 P S I , it indicates
trouble in the p u m p , steering ge ar, cylin de r, or a com bination
of these parts. T o elim inate the gear, close the gauge valve
and q u ickly test pressure of the p u m p o n ly w ith the engine at
w a rm id le ; then open the valve to avoid increasing oil
tem p eratu re .
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL