METAL BODY REPAIR - OD1653 - LESSON 2/TASK 2
this core. The diamondshaped cell construction resembles the Ushaped cell
construction except that the ribbons zigzag in the same pattern as the fins,
thus creating diamond shaped air passages. The water passages between the
ribbons are irregular and therefore more efficient in cooling, but are more
easily clogged. Each fin has many bumps and ridges, called deflectors,
which increase the cooling area exposed to the air. Some honeycomb cores
have square cells. The water has much farther to travel here than in a
diamond cell core, since the continuous water passages are alternately
vertical and horizontal rather than diagonal. The honeycomb type core has
several disadvantages. Although it exposes a large surface to the air, it
is rather frail, and its irregular passages clog easily. Much of the
external surface of honeycomb radiators dispels heat indirectly and hence
loses effectiveness. It is also difficult to manufacture metal ribbon of
the thinness used in honeycomb radiators without producing holes,
excessively thin pieces, or steel burrs that may rust out and cause leaks.
The honeycomb core is used mainly on passenger cars and light duty trucks.
Radiator cleaning has three purposes: to restore perfect radiation, to
facilitate soldering, and to remove obstructions to water circulation.
Various chemical salts and dirt found in the water of different localities,
together with grease and oil that find their way into the cooling system,
collect inside the water passages of the radiator and insulate the water
from the metal or stop circulation. This overheats the engine. Rust,
disintegrated rubber hose, and accumulated deposits from antifreeze or stop
leak preparations will have the same effect. The water passages may be
cleaned by pressure flushing, boiling, or rod cleaning. Dust, lint, and
bugs often adhere to the fin surfaces in sufficient quantity to restrict the
air flow through the radiator and decrease its efficiency. Spray cleaning
is then necessary.
(1) Flow Testing.
(a) Before a radiator is cleaned, it should be flow tested to
determine how badly it is clogged. The flow tester is used for this
purpose. This tester indicates the exact amount of water that