PRIN. OF INTERNAL COMBUSTION ENGINES - OD1619 LESSON 2/TASK 3
boiling point, is noncorrosive, has no odor, and gives complete protection against
freezing in normal use. Ethylene glycol gives a maximum protection against
freezing to 65 F (53.8 C) when it is mixed to a solution of 60 percent with 40
If the proportions of ethylene glycol are raised in the solution, it will result in
a higher freezing point for the solution, consequently having less protection. If
a 100percent solution of ethylene glycol were used, its freezing point would be
much below that of water. Other antifreeze solutions, however, do not show this
increase of freezing point with increasing concentration. Two good examples are
methyl alcohol which freezes at 144 F (97.8 C), and ethyl alcohol which freezes
at 174 F (114.3 C).
(2) Corrosion Resistance. The cooling system must be free of rust and scale in
order to maintain its efficiency. The use of inhibitors or rust preventatives will
reduce or prevent corrosion and the formation of scale. Inhibitors are not
cleaners and, therefore, will not remove rust and scale that have already
accumulated. Most commercially available antifreeze solutions contain inhibitors.
If water alone is used as a coolant, an inhibitor should be added.
d. Radiators (figure 65 on the following page). Radiators for automotive vehicles
using liquid cooling systems consist of two tanks with a heat exchanging core
between them. The upper tank contains an outside pipe called an inlet. The filler
neck generally is placed on the top of the upper tank; attached to this filler neck
is an outlet to the overflow pipe. The lower tank also contains an outside pipe
that serves as the radiator's outlet. Operation of the radiator is as follows:
(1) The upper tank collects incoming coolant and, through the use of an internal
baffle, distributes it across the top of the core.
(2) The core is made of numerous rows of small vertical tubes that connect the
upper and lower radiator tanks. Sandwiched between the rows of tubes are thin
sheetmetal fins. As the coolant passes through the tubes to the lower tank, the
fins conduct the heat away from it and dissipate it