Chevrolet 70 1969 Series, Shop Manual

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RADIATOR AND SURGE TANK 13-4
entering through overflow tube unseats vacuum
valve and allows atmosphere to enter system. The
overflow pipe connects to valve outside the valve
seal; thus no liquid or air can escape from the
system when both valves are closed.
PRESSURE RELIEF VALVE TESTING
NOTE: A special testing kit which can be ob­
tained locally is recommended for testing the
operation of pressure relief valve.
Pressure relief valve can be tested after
removing cap or valve from system . Instructions
supplied with testing kit should be followed to
assure proper check of unit.
RADIATOR SURGE TANK
A separate radiator surge tank as used on all
tilt models is mounted to rear of control island
framing. Tank serves as a coolant reservoir
for the radiator core which is mounted low to front
of engine. Hoses and pipes connect tank to radiator
and water pump. Supply tank incorporates the cool­
ing system filler cap which is accessible from
inside cab through small door at top of seat riser.
To gain access to supply tank itself, tilt cab
forward.
At regular intervals check tank and connect­
ing hoses for leaks. Keep hose clamps tight.
SPECIFICATIONS
COOLING SYSTEM PRESSURE RELIEF VALVE
...R C - 1 2 - 9 #
7.9 to 10 psi.
Com bination Filler Cap and V alve T y p e :
S ta m p e d ..........................................
Opening P re ssu re .............................
C O O LIN G SYSTEM NOTES A N D PRECAUTIONS
1. Overheating is not always caused by a defective cooling system; incorrect
ignition timing, dragging brakes, under-inflated tires, and improper use of trans­
mission gears can cause overheating.
2. Keep water pump and fan drive belts at proper tension. Refer to ENGINE
COOLING SYSTEM (SEC. 6K).
3. Do not over-fill cooling system. Expansion of coolant when hot will cause
loss of coolant through overflow tube.
4. Do not remove radiator filler cap when engine is hot. Wait until system
cools off.
5. Do not pour cold water into cooling system when the engine is hot. Wait
until system cools off.
6. If cooling system requires frequent refilling, check for leaks.
7. Keep all connections tight, and make sure gasket on radiator filler cap is
in good condition.
8. When filling system with anti-freeze solution ALWAYS FOLLOW RECOM­
MENDATIONS of anti-freeze manufacturer.
9. Use only Ethylene Glycol base coolant meeting GM Specification 1899-M. DO
NOT use Glycol Ether (Methoxy Propanol Type) in Toro-Flow II Engines.
10. Drain and flush cooling system every other year, preferably at the begin­
ning or end of winter operation.
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK SH O P M A N U A L