SYMPOSIA PAPER Published: 01 January 1999

Testing of Organic Acids in Engine Coolants


The effectiveness of 30 organic acids as inhibitors in engine coolants is reported. Tests include glassware corrosion of coupled and uncoupled metals, FORD galvanostatic and cyclic polarization electrochemistry for aluminum pitting, and reserve alkalinity (RA) measurements. Details of each test are discussed as well as some general conclusions. For example, benzoic acid inhibits coupled metals well but is ineffective on cast iron when uncoupled. In general, the organic acids provide little RA when titrated to a pH of 5.5, titration to a pH of 4.5 can result in precipitation of the acid. Trends with respect to acid chain length are reported also.

Author Information

Weir, TW
ARCO Chemical Company, Newtown Square, PA
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Developed by Committee: D15
Pages: 7–22
DOI: 10.1520/STP38236S
ISBN-EB: 978-0-8031-5566-4
ISBN-13: 978-0-8031-2610-7