GMC 1989 Light Duty Truck, Руководство по ремонту, Страница: 515 / 998

V8 ENGINE 6A5-25
1?
S e a l ru n n in g s u rfa c e s w ith a n o n -a b ra s iv e
cleaner.
Inspect
— C ra n k s h a ft fo r c ra c k s . U se th e m a g n a flu x
m ethod, if available.
— C ra n k p in s , m ain b e a rin g jo u rn a ls and th ru s t
surfaces for scoring, nicks, or dam age caused by
lack of lubrication.
— M ain bearing inserts for sco ring or other dam age.
In general, the lower inserts (except the #1 bearing)
show greater wear and the most distress from fatigue. If,
upon inspection, the lower insert is suitable for use, it can
be assumed that the upper insert is also satisfactory. If
the lower insert shows evidence of wear or damage, both
the upper and lower inserts must be replaced.
M easure (Figures 47 and 48)
— M a in b e a rin g a n d c o n n e c tin g rod jo u r n a l
d ia m e te r s ( f ig u r e 4 7 ). C o m p a r e w ith
“ S p e c ific a tio n s .” G rind or replace the cran ksha ft
if necessary.
— Main bearing and co nn ectin g rod jo u rn a ls for
ta pe r and out-of-round (figure 47). If the jo u rn a ls
are tapered or out-of-round m ore than 0.001-inch,
grind or replace the crankshaft.
— C rankshaft run-out (figure 48).
• Mount the crankshaft in V-blocks or between
centers.
• Use a dial indicator as shown.
• If the m ain jo u rn a ls are m isa lig n e d , the
crankshaft is bent and must be replaced,
along with the main bearing.
Crankshaft Bearing Availability
C rankshaft main and connecting rod bearings are
available in 0.001, 0.002, 0.010, and 0.020-inch undersizes.
OIL FILTER BYPASS VALVE
D isassem ble (Fig ure 49)
❖
1. Bolts (321).
2. Oil filte r bypass valve (320).
Clean
— Oil filte r bypass valve.
— Oil passages in the block.
Inspect (Figure 49)
Valve disc (item A) and sp ring for dam age or
sticky operation. R eplace the assem bly if faulty.
*
A ssem ble (Figure 49)
1. Oil filte r bypass valve (320).
2. Bolts (321).
&
Tig h ten
Bolts (321) to 9.0 N-m (80 in. lbs.).
F igure 4 8 — C hecking C ran kshaft R un-O ut