Chevrolet 70 1969 Series, Shop Manual

Page: 484 / 913

STEERING SYSTEM 9B-35
CONTROL VALVE A N D POWER STEERING GEAR (Cont.)
C O N D I T I O N
C A U S E
R E M E D Y
8. Tru ck leads to one
side or to the other.
Due to fro n t end m isalignm ent.
U n b alan ced or b ad ly w orn valve.
N O T E : If this is the cause, steerin g effort w ill be
ve ry light in directio n of lead and h e a vy in op p o­
site d irection.
A d ju st to specification.
R ep lace valve.
9. M o m e n ta ry in ­
crease in effort
when turning
wheel fast.
Low oil level in pum p.
Pum p b elt slipping.
C heck oil level in pum |l re servo ir and bring to proper level.
Tighten or rep lace belt.
10. Excessive wheel
kick-back or loose
steering.
Lash in steerin g linkage.
A ir in the system .
Ex cessive lash betw een pitm an sh aft sector and
ball nut.
Loose th ru st b earing ad ju stm en t.
A d ju st parts affected.
Ad d oil to
pump reservoir.
A d ju st to specification.
Rem ove steerin g g ear and a d ju s t to specification.
11. Steering wheel
surges or jerks
when turning with
engine r u n n in g —
especially during
parking.
Loose pum p belt. A d ju st to sp ecification.
12. H ard steering
when parking.
Loose pum p belt.
Low oil level in reservoir.
A d ju st to specification.
Fill to proper level. If ex cessively low. check all lines and jo in ts
for evid en ce of ex ternal leakage.
Lack of lu b ricatio n in linkag e for front Susp ension . Add lu b ricant w h e re needed as describ ed in lub rication (S e c . 0 )
of this m anual.
T ires not p ro p erly in flated . In flate to reco m m end ed p ressure.
In su fficien t oil p ressure. If all of the above ch ecks do not reveal the cause of hard steering ,
m ake the follow ing tests of oil p re ssu re:
a. D isconnect the p re ssu re line at oil pum p. A ttach gauge to pum p.
C onnect the hose to end of gauge w h e re the va lve is located,
b. W ith the engine at w arm idle and gauge va lve open, note the
oil p ressure on the gauge w h ile tu rn in g stee rin g w h eel from one
ex trem e position to the other. E sp e c ia lly note the m axim um
p ressure w hich can be b u ilt up w ith the w heel held in eith e r
right or left ex trem e position.
C A U T I O N : Do not hold w h eel in
ex trem e position for an extend ed period of tim e b ecau se it w ill
d ra stica lly in crease the oil te m p era tu re and w ill cause undue
w ea r on the oil pum p.
c. W ith oil te m p era tu re b etw een 150 degrees F and 170 degrees
F, as m easured w ith a th e rm o m e te r in the reservo ir, the m a x i­
m um oil p ressu re should not be less than 600 P S I for s a tis ­
factory p o w er steerin g op eration.
d. If the m axim um oil p re ssu re is less than 600 P S I, it in d icates
tro ub le in the pum p, steerin g gear, cylin d er, or a com b ination
of these parts. To elim in a te the gear, close the gauge va lve
and q u ick ly test p ressu re of the pum p on ly w ith the
engine at
w arm id le ; then open the v a lv e to avoid in creasin g oil
tem p eratu re.
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SHOP M ANUAL