Cadillac 1975 Owner's Manual page 69

flow is collected in the recovery tank. When
the system temperature drops, the coolant is
drawn back into the radiator. The cooling sys¬
tem has been filled at the factory with a high-
quality, inhibited, year-around coolant that
meets the standards of General Motors
Specification 1899-M. This coolant solution
provides freezing protection to -40°F., and it
has been formulated to be used for two years
or 30,000 miles. After two years or 30,000
miles, the coolant should be drained to pre¬
vent rust or corrosion in the radiator and en¬
gine.
Cooling System Care — Do not remove
radiator cap to check coolant level, but check
visually in the "see thru" coolant recovery
tank, Fig. 5-1, as frequently as needed. Level
should be at the "full cold" mark on the re¬
covery tank when the system is cold, and at the
"full hot" mark at normal operating tempera¬
ture. Add a 50/50 mixture of high-quality
ethylene glycol antifreeze and water to the
recovery tank for coolant additions. If frequent
additions are required, see your dealer for a
cooling system check.
NOTE: If recommended quality antifreeze is
—1
used, supplemental inhibitors or additives
__J
claiming to provide increased cooling capa¬
bility are not necessary. They may be detri¬
mental to the efficient operation of the sys¬
tem, and represent an unnecessary operating
expense.
The cooling system should be serviced
every year as follows:
• Wash radiator cap and filler neck with
clean water.
• Check coolant for proper level and freeze
protection.
• Test system and radiator cap for proper
pressure holding capacity (15 psi). If re¬
quired, use cap designed by AC for cool¬
ant recovery systems and specified for
your Cadillac.
• Tighten hose clamps and inspect all
hoses. Replace hoses every 24 months;
earlier if swollen, checked, or otherwise
deteriorated.
• Clean frontal area of radiator core and air
conditioning condenser.
Every two years or 30,000 miles, whichever
occurs first, the cooling system should be
flushed and refilled using the following re¬
commended procedure:
1. Remove radiator cap when engine is
cool:
• Rotate cap slowly counterclockwise
to detent (Do not press down while
rotating).
• Wait until residual pressure (indicated
by a hissing sound) is relieved, then
press down on cap and continue to
rotate counterclockwise.
| CAUTION: To avoid the danger of being |
burned, do not remove radiator cap while |
engine and radiator are still hot because '
| scalding fluid and steam will be blown out |
I under pressure.
2. Run engine, with radiator cap removed,
until upper radiator hose is hot (indi¬
cates thermostat is open).
3. Stop engine and open radiator drain
valve to drain coolant. (Operation may
be speeded by removing drain plugs in
the block.)
4. Close valve (install block drain plugs, if
removed) and add sufficient water to
fill system.
5. Repeat steps 1,2, 3, and 4, a sufficient
number of times until the drained li¬
quid is nearly colorless.