Volume 4, Issue 8 (September 2007)
Heavy-Duty Diesel Engine Cavitation Test
The objective of this study was to develop a test procedure to evaluate the ability of a heavy-duty diesel engine coolant to provide protection against damage resulting from a phenomenon known as cylinder liner cavitation corrosion. The engine cavitation test procedure was developed by modifying a production OEM diesel engine to consistently produce the operating conditions that accelerate damage from cylinder liner cavitation. The resulting, 250-h test procedure was able to quantify a coolant’s ability to protect wet-sleeve cylinder liners from cavitation corrosion. Dozens of coolants were evaluated using this test procedure. The ranking of cylinder liner pit area counts from this procedure’s discrimination matrix was in agreement with the ranking of pit area results seen in high-mileage field tests. Conversely, upon investigation, an acceptable correlation could not be established between field test pit area counts and the results from a known bench test. Obtaining results in a few weeks from a short duration procedure such as this can offer a coolant formulator advantages compared to waiting for the completion of a properly conducted field test. This test procedure creates an accelerated, yet realistic level of liner cavitation that ranks protection levels of coolants being evaluated. This ranking or discrimination is often not possible in field testing because the field test is run under mild service conditions or the engine components have little tendency to promote liner pitting. In addition, the difficulty in controlling field tests often yields unusable, inaccurate results. The test procedure was shown to be repeatable within labs and reproducible between labs thus confirming the viability of this test procedure as a useful tool to assess a coolant’s ability to protect against cylinder liner cavitation damage. It is recommended that the presently developed test procedure be considered for adoption as an ASTM test method.