Water Jacket
other end of the adapter. The cap rubber gasket should
be wet to ensure an airtight seal. Then, by applying air
Some maintenance aspects in connection with the
pressure as specified for the particular cap, you can
water jacket have already been discussed, including
determine if it is capable of retaining the pressure as it
cleaning and preventing rust and corrosion. But where
should.
water jackets are badly clogged and do not respond to
Another tester used with cooling systems is the
regular or reverse flushing, the engine can be directly
antifreeze hydrometer, which is used to determine if
flushed through the core holes, also referred to as
adequate protection against freezing is afforded by the
freeze plugs. To do this, first remove some of the core
antifreeze solution in use. This hydrometer shows the
hole plugs from the cylinder block and head. Then,
specific gravity of the solution, thus giving you an
with a suitable length of small copper tubing attached
indication of what percentage of the solution is water
to the flushing gun nozzle, flush the water jacket
and what percentage is ethylene glycol. Then, by
through the openings. New plugs should then be
referring to a chart that corrects for the coolant
installed. Any plugs that show signs of leaking or
temperature, you can determine if additional antifreeze
rusting must be replaced. All drain plugs should be
should be added to the system. The accuracy of the
kept free of rust and scale. Gaskets must be in good
tester can be checked by taking a test reading of a
condition to prevent both internal and external leaks. If
mixture containing one part antifreeze and two parts
there are external leaks around gaskets, there may also
w a t e r, w h i c h s h o u l d t e s t t o 0 F. T h e t e s t e r
be internal leaks into the engine. Proper tightening of
manufacturer's instructions should be followed for
the head bolts or cap screws with a torque wrench is
proper use and care of the hydrometer. Accurate
essential for preventing leaks around the head gasket.
readings are not possible if the float and the inside of
If this fails to correct the difficulty, the gasket must be
the glass barrel are dirty.
replaced.
Before reading the tester, you should fill and empty
the hydrometer barrel several times to equalize the
Radiator
temperature of all parts. First, read the first number or
letter on the float above the surface of the liquid, and
The radiator should be checked for leaks,
then note the solution temperature from the first
particularly where the tanks are soldered to the core,
division or number above the top of the indicating
since vibration and pulsation from pressure can cause
column of the thermometer. These two readings
fatigue of soldered joints or seams. Neglect of small
should be made at the same time and as soon as
leaks may result in excessive leakage, rust clogging,
possible after drawing the solution into the
overheating difficulties, or complete radiator failure.
hydrometer. The freezing protection of the solution is
Thus, it is extremely important to keep the radiator
determined by matching float and thermometer
mounting properly adjusted and tight at all times and to
readings of the chart on the hydrometer. Tests will be
detect and correct even the smallest leaks. A leak
inaccurate if made immediately after adding water or
usually reveals its presence by scale marks or
antifreeze. Most antifreeze hydrometers give the most
watermarks below the leak on the outside of the core.
accurate readings at solution temperatures around
Contrary to popular belief, permanent antifreeze does
110F. Even with hydrometers designed to read at
not leak through spaces where water won't pass. What
solution temperatures below 0F, tests should always
actually occurs is that the antifreeze leak is more
be made with the temperature of coolant above 60F, if
noticeable, since it does not evaporate as quickly as
possible, because the solution is more viscous when
water. Often, small leaks can be effectively mended by
cold. This condition prevents the float from finding its
using one of several commercially available radiator
true level quickly and may result in a false float
sealers (powders or liquid-solder compounds), which
reading.
harden upon contact with the air, thus sealing off any
small openings. Leaks can also be repaired by ordinary
REPAIRING COOLING SYSTEM
soldering. When large leaks or considerable damage is
COMPONENTS
present, removal of the radiator for extensive repair or
replacement is usually required.
The individual components of the cooling system
Bent fins should be straightened and the radiator
that require servicing and repair include the water
core checked for any obstructions that could restrict
jacket in the cylinder block and head, radiator, hoses,
water pump, fan and fan belt, and thermostat.
the airflow. Radiator air passages can be cleaned by
5-12
