Table 5-1.--Permanent Antifreeze Needed Per Gallon of
system will be indicated by bubbling in the pail of
Cooling System Capacity
water. Air leaks are usually corrected by tightening the
hose clamps of the hose connecting the radiator to the
Pints
Protection to:
water pump or replacing the hose, if necessary. The
trouble may also be caused by a leaking water pump or
+10F
2
exhaust gas leakage.
0F
2 3/4
Exhaust gas leaking into the cooling system,
usually as a result of a leaking cylinder head gasket,
-10F
3 1/4
will result in damage to the system due to the action of
-20F
3 1/2
acids formed in the system. To check for exhaust gas
leakage, remove the fan belt, upper radiator hose, and
-30F
4
thermostat. Then drain out some coolant until its level
is just above the top of the cylinder head. If the engine
-40F
4 1/4
is accelerated quickly several times, exhaust gas
leakage will generally reveal itself by bubbling at the
-50F
4 1/2
thermostat outlet or by a rise in coolant level beyond
-60F
that caused by normal coolant expansion.
4 3/4
A radiator pressure tester can also be used to check
for leaks. The device is installed on the radiator filler
than this, little, if any, advantage results. A straight
neck in place of the pressure cap. Then air pressure is
ethylene glycol (100 percent) affords less protection
applied and the gauge observed for a pressure drop,
than one containing 60-percent ethylene glycol and
which would indicate a leak. Pressure should not
40-percent water. In other words, up to a point, the
exceed that recommended by the manufacturer. On a
water acts as "antifreeze" for the ethylene glycol.
system with a 14-pound pressure cap, for example, do
not apply more than 15 psi. If the leak cannot be
After adding the required amount of antifreeze,
located externally, inspect the engine oil to determine
you should fill the system with clean water, leaving
whether coolant is leaking into the crankcase due to a
room for the expansion, and operate the engine to mix
cracked cylinder block or leaking head gasket.
the solution. Then add water, if necessary, to bring the
coolant level to that prescribed for the vehicle. You
To check for compression or combustion leakage,
should then stop the engine and check the solution with
run the engine until it reaches normal operating
an antifreeze hydrometer to make sure the system is
temperature. Then pressurize the system with the
protected to the desired temperature.
engine running. Fluctuating pressure as the engine is
accelerated indicates a combustion leak. In the case of
Most modern high-compression engines,
a V-8 engine, you can determine which bank is at fault
especially those equipped with air-conditioning,
by disconnecting the spark plug leads from one bank
require the use of antifreeze year round for efficient
and running the engine on the other. The combustion
performance of the cooling system and engine.
leak is in the bank furnishing the power when the
pressure fluctuates. To determine which cylinder is
Cooling System Testing
leaking, disconnect the spark plug wires one at a time
and observe the tester dial. When the plug wire is
It is often necessary to check the cooling system
removed from the leaking cylinder, the indicator will
for leaks that are hard to find. Leaks in the cooling
stop fluctuating. If more than one cylinder leaks,
system should not be permitted to continue, since
removing the plug lead from an offending cylinder will
boiling and overheating will tend to occur, resulting in
cause the fluctuation to become less frequent. If
breaking down the oil film and possibly damaging the
tightening the cylinder head to specifications does not
engine. Air will be drawn into the system if leaks are
stop the leak, replace the head gasket and recheck for
present between the radiator and water pump, causing
leakage.
foaming and loss of coolant, as well as accelerating
rusting and corrosion. To check for such leaks, connect
You can use the radiator pressure tester to test the
a hose to the overflow pipe and place the other end of
radiator pressure cap by using an adapter provided for
the hose in a pail of water. If the system is full and the
this purpose. The adapter is screwed onto the lower
end of the tester, and the pressure cap is installed on the
warmed-up engine is running, any air drawn into the
5-11
