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COOLING SYSTEM
7-11
WARNING: ANTIFREEZE IS POISONOUS.
KEEP
OUT OF THE REACH OF CHILDREN.
Submerge t h e thermostat i n a container o f pure a n -
tifreeze and suspend i t so t h a t i t does n o t touch t h e
sides or the b o t t o m o f the container.
Suspend a thermometer i n the antifreeze so t h a t i t
does not contact the container or thermostat.
WARNING: DO NOT BREATHE THE VAPOR. EN-
SURE THE TEST AREA IS PROPERLY VENTILATED.
H e a t the antifreeze. A p p l y a s l i g h t tension o n the
feeler gauge w h i l e the antifreeze is heated. W h e n t h e
valve opens t h e feeler gauge w i l l slip free f r o m t h e
valve. Note t h e temperature (Fig. 5). I f defective, re-
place the thermostat.
THERMOMETER
Must Be Open 0.076 mm (0.003 inch)
8 8 - 9 3 0 C
(192°-199°F)
Must Be Fully Open
I O 4 0 C (220°F)
J9007-31
Fig. 5 Thermostat Calibrations
I n s t a l l t h e thermostat. Refer to "Thermostat Re-
m o v a l " section i n t h i s group.
THERMOSTA
T
REMOVAL
WARNING: DO
NOT
LOOSEN THE
RADIATOR
DRAINCOCK WITH THE SYSTEM HOT AND PRES-
SURIZED BECAUSE SERIOUS BURNS FROM THE
COOLANT CAN OCCUR.
Do n o t waste reusable coolant. I f the solution i s
clean and being drained only to service t h e cooling
system, d r a i n t h e coolant i n t o a clean container for
reuse.
(1) Disconnect b a t t e r y negative cable f r o m b a t t e r y
negative t e r m i n a l .
(2) D r a i n cooling system u n t i l coolant level i s be-
l o w thermostat. Refer to " D r a i n i n g Cooling System"
i n t h i s section.
(3) Remove r a d i a t o r hose f r o m thermostat housing.
(4) Remove thermostat housing m o u n t i n g bolts,
thermostat housing, gasket, and thermostat (Fig. 4).
Discard old gasket.
(5) Clean gasket m a t i n g surfaces.
THERMOSTAT
INSTALLATION
I f t h e thermostat is being replaced, ensure t h a t t h e
replacement is t h e specified thermostat for the vehi-
cle model and engine type.
(1) D i p the replacement gasket i n w a t e r a n d i n s t a l l
on i n t a k e manifold (Fig. 4).
(2) Insert t h e r m o s t a t (spring side down) t h r o u g h
gasket i n t o opening i n i n t a k e manifold. Center ther-
mostat i n manifold.
CAUTION: Tightening the housing unevenly or with-
out thermostat centered in recess in thermostat
housing may result in a cracked housing.
(3) I n s t a l l housing over thermostat. Ensure t h a t
thermostat
is positioned i n t o recess i n housing.
T i g h t e n m o u n t i n g bolts to 23 N-m (200 in-lbs).
(4) Connect battery negative cable t o battery.
(5) F i l l cooling system. Refer to " R e f i l l i n g Cooling
System" i n t h i s group.
COOLANT
The cooling system is designed around the coolant.
Coolant flows t h r o u g h t h e engine water jacket ab-
sorbing heat produced d u r i n g engine operation. T h e
coolant carries the heat t o r a d i a t o r and heater core
where i t is transferred to t h e ambient a i r passing
t h r o u g h the radiator and heater core fins. T h e cool-
ant also removes heat from the automatic t r a n s m i s -
sion f l u i d i n vehicles equipped w i t h a n automatic
transmission.
COOLANT
PERFORMANCE
The required ethylene-glycol (anti-freeze) and w a -
ter m i x t u r e depends upon climate and vehicle oper-
a t i n g conditions. The coolant performance o f various
m i x t u r e s follows.
P u r e W a t e r - For the purpose o f heat transfer only,
water is able t o absorb more heat t h a n a m i x t u r e o f
w a t e r a n d ethylene-glycol. B u t , water freezes a t a
h i g h e r temperature and allows corrosion.
1 0 0 % E t h y l e n e - G l y c o l -
T h e corrosion
i n h i b i t i n g
additives i n ethylene-glycol need t h e presence of wa-
ter t o dissolve, w i t h o u t water they f o r m deposits i n
the system w h i c h act as i n s u l a t i o n causing the t e m -
perature to rise t o as h i g h as 149°C (300°F) w h i c h i s
hot enough to m e l t plastic and soften solder. The i n -
creased temperature can result i n engine detonation.
I n addition, 100 percent ethylene-glycol freezes a t -
22°C (-8°F).
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