ARE AND A1NTENANCE
Page 51
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Play it cool all the year
NOW that it is normal practice to leave anti-freeze in the engine all the year round, it's well worth buying a. hydrometer to check the specific gravity. Make sure the right proportion of anti-freeze in the coolant is kept up, particularly after any part of the system has been drained
We all know that water starts to solidify at 0° C, but even in transport not everyone appreciates that the water starts to expand when the temperature falls to about 4' C. As the water solidifies, so the expansion continues, and the volume of the solid ice can be 9 per cent greater than that of the water.
If the water is allowed to freeze in the engine, the cylinder block is likely to crack or the core plugs will be blown out by the force of the expanding ice. Since the radiator contains less water, and there is a space in the top tank for expansion. it is less likely to crack — and if it does, it is far less costly than a cracked block.
The presence of the antifreeze solution in the water does not raise the temperature of the coolant, but reduces the temperature at which solidification starts. Ethyl alcohol, methyl alcohol and ethylene glycol can be used as anti-freeze solutions, but in any case an anti-corrosion inhibitor is needed. So it's false economy indeed to use a home-brewed mixture.
Nowadays, ethylene glycol is the standard anti-freeze mixture, since it gives very good protection, and has some other worthwhile features.
If a 25 per cent solution of ethylene glycol is used — 25 per cent anti-freeze, 75 per cent water — then the freezing temperature drops to about — 12c C. With a 50 per cent solution, the freezing temperature drops right down to —37° C, which should be enough for almost any transcontinental route. But to be on the safe side always allow for a lower temperature than you are likely to meet.
Boiling point Fairly strong solutions of anti-freeze are sometimes used in very hot countries because ethylene glycol has a much higher boiling point than water — 197° C. to be precise. Depending on the pressure of the system, therefore: a 50 per cent solution should give protection against boiling up to somewhere in the region of 130-140° C at least.
Remember that when antifreeze is added It expands a little more than water, so a little more clearance for expansion must be left in the top tank or header tank. The space should be about one pint to every three gallons with a normal 25 per cent solution.
Because they have corrosion inhibitors, anti-freeze solutions can give longer engine life than can pure water. The engine coolant passages will remain cleaner, so blockages are less likely to occur, while the water pump sealing face is far less likely to be attacked by debris and scale