Therm Ostat And W Ater O U Tle; Crankshaft And Bearings - Chevrolet 1988 Light Duty Truck Repair Manual

6A2-18 2.8 LITER V
k
A. Grind out th is portio n .
Figure 26— Scale for Checking Valve Spring
Installed Height
• C o m p re ss th e valve sp rin g using J 8062
(figure 24). Com press the spring enough so
the lower valve stem groove can be seen
clearly.
• Push a new O-ring seal (26) onto the valve
stem. The seal is to be installed on the stem 's
lower groove. Make sure the seal is flat and
not twisted.
• Apply a small am ount of grease to the area of
the upper valve stem groove. Assem ble the
two valve keepers using the grease to hold the
keys in place. Make sure the keepers seat
properly in the groove.
• Release the com pressor tool. Make sure the
valve keepers stay in place.
• Repeat the preceding steps on the rem aining
valves.
m
M easu re
Valve spring installed height of each valve spring as
follows.
1. Use a narrow thin scale. A cutaway scale
(figure 26) may be helpful.
2. Measure from the top of the spring dam per
" fe et" to the bottom of the oil shedder on the
exhaust valve or to the bottom of the valve cap
on the intake valve.
3. If this m easurem ent exceeds the figure given
in " S pecifications," install valve spring seat
sh im s a p p ro x im a te ly 0.75 mm (0.03-inch)
thickness (between the spring and cylinder
head). NEVER shim the spring so as to give
an installed height under the specified figure.
THERMOSTAT AND WATER
OUTLET
R em o ve o r D is c o n n e c t (F ig u re 27)
1.
Bolts.
2. Water outlet.
3. Gasket.
4. Therm ostat.
]?
In sp ect
Water outlet for cracks.
-6
B-05248
Install or C o n n ect (F ig u re 27)
1. Therm ostat.
2. New gasket.
3. Water outlet.
4. Bolts.
T ig h ten
• Bolts for 21 N m (15 ft. lbs.).

CRANKSHAFT AND BEARINGS

CLEANING AND INSPECTION
« g i
Clean
Crankshaft with solvent.
— Do not scratch the bearing journals.
— Blow all sludge from the oil passages with
compressed air.
Main bearing inserts. W ipe free of oil with a soft
cloth.
In sp ect
L,
• Crankshaft for cracks. Use the m agnaflux method, 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 damage caused by
lack of lubrication.
• Main bearing inserts for scoring or other damage.
In general, the lower inserts (except the #1 bearing)
show greater wear and the most distress from fatigue. If
the lower insert shows evidence of wear or damage, both
the upper and lower inserts m ust be replaced.
m
M easu re
Main bearing and connecting rod journal diam eters
(figure 28). Compare with " S pecifications." Replace
the crankshaft if necessary.
Main bearing and connecting rod journals for taper
and out-of-round (figure 28). If the jo u rn a ls are
ta p e re d or o u t-o f-ro u n d m ore th a n 0.005 m m ,
replace the crankshaft.