Chevrolet CHEVY VAN G10 SERIES Service Manual page 173

ENG INE C O O LING 6K-4
5. Submerge th e valve com pletely and agitate th e water
thoroughly. U nder this condition the valve should open
fully.
6
. Remove the th erm o stat and place in a 33% glycol
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solution ° below tem perature indicated on the valve.
7. With valve com pletely subm erged and w ater agitated
thoroughly, th e valve should close com pletely.
8
. I f th erm o stat checks satisfactorily, re-install, using a new
housing gasket.
9. Refill cooling system .
Thermostatic Fan Clutch
Replacement
All m ating surfaces (w ater pum p hub and fan clutch h u b )
should be inspected for sm ooth m ating surfaces and rew orked
as necessary to elim inate burrs or o th e r im perfections. Except
for the fan b elt, com ponents should be assem bled to the
engine (See W ater Pum p Removal an d Installation Procedures).
Radial ru n -o u t should be checked as follows:
1. Secure the fan blade to prevent ro tatio n . (See Figure
2. M ount a dial indicator (.001 graduations) to the engine
and place th e indicator pointer on the fan blade spider.
Preferably on th e longest ban d or space on th e spider.
(See Figure 7).
3. R o tate th e w ater p u m p pulley in one direction and note
the to ta l am o u n t o f indicator needle m ovem ent. This
represents th e to ta l radial ru n -ou t. M ark the p o in t on the
pulley at w hich the highest reading is obtained.
4. I f th e to tal indicator reading is less th a n .006 inch, the
assem bly is w ithin specification. Install fan belt and
adjust.
If th e to ta l indicator run-out exceeds .006 inch, p ro ­
ceed to Step 5.
5. Divide the to ta l indicator reading in h alf and o btain this
thickness from shim stock (1 /2 x 3 /4 ) and rew ork
8
(Figure ). Place this shim pack betw een the w ater pum p
Fig. 5 —Replacing Therm ostat
Fig. 6—Securing Fan Blade
6
).
pulley and fan clutch hub at th e b o lt closest to th e point
m arked on th e pulley in Step 3. I f th e m ark on th e pulley
is betw een tw o bolts so th a t it is difficult to determ ine
w hich b o lt is closest, place tw o shim packs; one under
each b o lt on either side o f th e m ark. (See Figure 9).
Bolt Torque Sequence
a) When one shim pack is used, first, to rq u e th e b o lt
over w hich the shim pack has been placed; second,
th e b o lt opposite the first; and finally, th e other
tw o. R ecom m end to rq u e is 25 lbs. ft.
b ) When tw o shim packs are used, each b o lt m ust be
to rq u ed partially; th en to full to rq u e alternating
betw een opposite bolts; th e n th e oth er tw o bolts in
th e same m anner. R ecom m end to rq u e 25 lbs. ft.
N O T E : Excessive run-out may result if the above
sequence and recommended torque is not used.
Fig. 7—Checking Run-out
C H E V Y V A N S H O P M A N U A L