nhibiting Corrosion in the Cooling System
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'FIE potentially dangerous effects of combustion-gas leakage into a ooling system containing anti-freeze :lution were reviewed during the disission of Mr. S. J. H. Dyson's paper Vehicle Engine Cooling System Operaan and Techniques Developed to Miniize Maintenance Costs', at a meeting of ic Institute of Road Transport Engineers, idlands centre, last weekânotably with gard to diesel engines which are built ith a high preponderance of cast iron, id were. it was claimed by the author, ore prone to leakage than petrol igines. Mr. Dyson is trade-sales techcal supervisor of the Motor Accessory ivision of S. Smith and Sons (England) Id.
Leakage resulted, said Mr. Dyson, in e formation of sulphurous acids that pidly corroded the ferrous parts of the Stem unless a suitable inhibitor were nplcncd. This should preferably be of e acid-buffer type (in the case of a esel) which had a high reserve alkaiity, rather than the film-producing type hich created a barrier betWeen the oolant and the metal surface.
In agreement with a member, Mr. yson confirmed that the pH content of le coolant could be checked only by a pH meter. which was costly and required expert handling, but emphasized that a cooling system analyser could be employed to check leakage (which causes fluctuations of he dial needle) as well as air tightness and operation of the pressure cap, the system being initially pressurized with the aid of a pump.
Replying to a question, Mr. Dyson observed that a completely sealed system would reduce oxidation of the anti-freeze and extend its useful life because it would obviate loss of coolant and aeration. The rate of inhibitor depletion depended to a large extent on the condition of the cooling system at the time of its introduction, a corroded system making greater demands on the solution in terms of accelerated inhibitor depiction.
In reference to thermostats, Mr. Dyson said that a jiggle pin could be used in place of a bleed hole to increase the rate of warming-up because it allowed the air in the system to be displaced when the radiator was being filled, but prevented the passage of water before the valve opened. A wax thermoStat had the advantage that it was not sensitive to pressure variations and the disadvantage that it failed closed.