Chevrolet 70 1969 Series, Shop Manual

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ENGINE C O O L IN G SYSTEM 6K-7
Figure 4—Cooling System Water Filter
Installed (Typical!
Suspend thermostat and thermometer in water
with thermometer located close to thermostat.
Thermostat must be completely submerged and
water thoroughly agitated while heating. Apply heat
to the water and record both the temperature at
which the thermostat begins to open and the temp­
erature at which the thermostat is fully open.
Compare temperature readings taken in the
test with those given under ’’Thermostats" in
"Specifications" at end of this section.
Do not attempt to repair thermostat. If ther­
mostat does not function properly, replace with new
unit which has been checked as directed above.
Use new gasket when installing thermostat.
Fill cooling system, then run engine until normal
operating temperature is reached. Check for cool­
ant leakage at thermostat cover gasket.
WATER FILTER
Water filter (fig. 4) as installed on some ve­
hicles is used to filter and condition water in
cooling system.
On a new engine, the filter
element should be initially changed after 2,500 to
3,000 miles. After initial change, the filter should
be serviced periodically 7,500 to 10,000 miles or
300 to 500 hours depending upon engine workload,
conditions, etc.
Except when anti-freeze is used, color of water
in system should be a golden yellow. No rust pre­
ventive or inhibitor should be used in system when
water filter is used.
IMPORTANT
Some permanent-type anti-freeze
solutions may contain inhibitor which
will produce a green residue or pre­
cipitation. If this is noted more fre­
quent element change periods will be
necessary and if this fails to correct
condition, the filter element should be
removed, or disconnected.
E L E M E N T R E P L A C E M E N T
N O T E : Key numbers in text refer to figure 5.
1. For convenience in changing element, close
off filter supply and return hose by clamping vise-
grip pliers to each hose. Care should be taken that
hose is not cracked or otherwise‘damaged.
2. Remove drain plug (5) from bottom of filter.
3. Remove two bolts (3) which attach cover (1)
to filter. Remove cover and cover gasket (2).
4. Remove upper plate (10), element (9), lower
plate (8), spring (7), and sump plate.(6) from filter
body (4). Flush out filter body.
5. Discard filter element, then clean all parts.
Examine element lower plate for excessive cor­
rosion. Deep pits in the plate do not warrant re­
placement. Clean plate by wire brushing. This
plate generates current for the electrochemical
action of filter element. If excessively corroded,
replace.
N O T E : When using Ethylene Glycol anti-freeze
solutions, install element identified by letters
"P A F "; also, when operating in mild climates
where no anti-freeze is required use the standard
chromate type filter element.
6. Referring to figure 5, position sump plate
(6), spring (7), lower plate (8), new element (9),
and upper plate (10) in filter body (4). Install
cover (1) using new gasket (2). Tighten cover
attaching bolts evenly and firmly. Install drain
plug (5) in bottom of filter body.
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK SH O P M A N U A L