Engine Coolant - GMC 1976 ZEO 6083 Maintenance Manual

13- 4 RADIATOR AND COOLANT RECOVERY SYSTEM
Figure 3-Coolant Recovery System, Type 1
reservoir is mounted above the radiator and is acces-
sible from the front access doors and connected to
the radiator filler neck with a hose . The coolant level
must be maintained at the "COLD" mark on the side
of the reservoir when coolant is cold . A gasket incor-
porated into the filler cap forms a seal at the radiator
filler neck . A leak at this gasket will result in loss of
coolant during normal operation . The pressure cap
must be installed so that the marking on top of the
cap aligns with the overflow tube on the filler neck .
Refer to Figures 3 and 4 for removal and installa-
tion of coolant recovery system components .
ENGINE COOLANT
COOLANT RECOMMENDATIONS
For coolant drain and refill procedure, refer to
SECTION 6K of this manual . Cooling system
maintenance intervals will be found in SECTION O.
Figure 4-Coolant Recovery System, Type 2
COOLANT TESTING
Always test solution before adding water or anti-
freeze . Engine should be warmed up to operating
temperature. Fill and empty tester several times to
warm tester before using. Keep tester clean inside
and out.
Some testers will indicate correct freezing point
only when test is made at a specific temperature.
Other testers are provided with thermometers and
tables and indicate freezing points corresponding to
readings made at various temperatures . Disregard-
ing temperatures of solution may cause an error as
large as 30°F. Read and be guided by instructions
furnished by the tester manufacturer .
In the event coolant freezes solid in extreme cold
weather, place vehicle in warm building or improvise
some means of thawing coolant before starting en
gine . Under no circumstance should engine be ope-
rated, when coolant is frozen solid. After thawing,
refill system with a higher concentration of anti-
freeze solution and start engine . Inspect entire sys-
tem for leakage and then test coolant with
hydrometer to determine if adequate anti-freeze pro-
tection is provided .
COOLANT PRECAUTIONS
1 . Overheating is not always caused by a defec-
tive cooling system ; incorrect ignition timing, drag-
ging brakes, under-inflated tires, can
cause
overheating.
2. Keep water pump and fan drive belts at proper
tension. Refer to ENGINE COOLING SYSTEM
(Section 6K) of this manual .
3 . Do not remove radiator filler cap when engine
is hot. Wait until system cools off.
4. Do not pour cold water into cooling system
when the engine is hot. Wait until system cools off.
5 . If cooling system requires frequent refilling,
check for leaks.
6 . Keep all connections tight, and make sure gas-
ket on radiator filler cap is in good condition.
7. When filling system with anti-freeze solution .
Always follow recommendations of anti-freeze
manufacturer .
8. Use only Ethylene Glycol base coolant meet-
ing GM Specification 1899M.
9. Drain and flush cooling system every other
year, preferably at start or end of winter operation.