METAL BODY REPAIR - OD1653 - LESSON 2/TASK 2
will flow, by gravity, through a radiator per minute. The reading indicated
on the tester is then compared with the flow rate of a new radiator or with
the specifications furnished by the manufacturer. The difference between
the actual rate and the specified rate indicates the amount the radiator is
(b) To use a flow tester, the radiator is set on the stand provided,
then a hose is connected to the radiator inlet. After the hose is connected
securely, the pump is turned on, and the water flow is adjusted until a
constant level is maintained in the tank.
Be careful when adjusting the flow rate. If you
accidentally push the lever too far, the water will
shoot out the top of the radiator onto the repairman.
The capacity of this tester is 90 gallons of water per
minute, and has given more than one person an unwanted
(2) Pressure Flushing. Pressure flushing forces water by air pressure
(approximately five psi) through the water passages of the core. It may be
accomplished in two ways: direct flushing, in which water is forced through
from top to bottom, as it flows in normal service; and reverse flushing.
The same equipment is required for both methods: water pressure, air
pressure, and a flushing gun.
(a) To clean a radiator by direct pressure flushing, screw the
radiator cap on the filler neck and attach a lead away hose to the outlet
connection of the lower tank. With the flushing gun in the inlet connection
of the upper tank, fill the radiator with water. Because water alone is
often insufficient to break loose the grease, sludge, rust, and scale within
the radiator, it may be necessary to add some good radiator cleaner. When
the deposits are loosened, turn the water off and admit compressed air to
the radiator in short blasts, adding water between blasts until the water
drains out clear and at a normal rate. The air must be applied gradually,
since the radiator will stand only a limited amount of pressure.