Combining Oil Analysis Tests to Identify the Root Cause of Machine Failures

The importance of selecting the correct test to analyze the performance of a piece of equipment cannot be isolated to a specific test; it requires the combination of two or more tests or a group of tests depending on the activity of the selected equipment in the production process. In order to keep the unit in the field, it is necessary to avoid constant failures and downtime due to corrective maintenance or in a worst-case scenario, the replacement of the unit as a consequence of a catastrophic failure.

Oil condition monitoring programs play a very important role in this particular matter, continuously testing a small portion of the lubricant in use for a very low cost in comparison to the value of a corrective action, such as full lubricant replacement or even more if a mechanical part or entire unit must be put down due to a breakdown.

The Problem

One of the principal issues is the difficulty in reviewing oil analysis reports on the maintenance site when you have conflicting results in the report. For this study, we are going to use as an example involving ASTM D2982-07 (Detecting Glycol-Base Antifreeze in Used Lubricants Oils1) together with ASTM D5185-18 (Multi-element Determination of Used and Unused lubricating Oils and Base Oils by Inductively Coupled Plasma Atomic Emission Spectroscopy ICP-AES1) on internal combustion diesel engines. When these two very different tools are used separately, the results could potentially be inconclusive, and any action could be inaccurate with expensive and/or catastrophic consequences due to the equipment operating out of manufactured conditions.

The combination of these two methods in oil analysis is an important tool for the verification of lubricant contamination with antifreeze in internal combustion engines. Each test method used individually, although important on its, own, may not tell the whole story. In this comparative study, we will develop more deeply the importance of these two methods used together as a complementary tool for the determination of component failure due to a coolant leak, the severity of the issue, possible solutions, and the future preventions of the issue.

The Goal

The advantage of correctly understanding an oil analysis report in the case of oil contamination due coolant intrusion on internal combustion diesel engines is monitoring the performance of the unit under not ideal conditions and when to decide to activate proactive, preventive or corrective maintenance due its operation conditions.

The presence of coolant in the crankcase could lead to corrosion or damage of some sensitive parts or components of the unit, which can be observed on the elemental analysis, but the presence and severity of the contaminant can be further identified with the colorimetric analysis. Besides the physical, chemical and thermo-degradation of the lubricant due to the presence of the contaminant, these two factors combined could determine the severity of the failure, predict the life of the lubricant to some degree, and help identify the root cause of the problem.

The oil analysis report interpretation must consider all of the tests for a better understanding in order to avoid expensive damage to the unit, excessive downtime due corrective maintenance or replacement of the entire unit.

Case Studies

Based on results from real equipment, working in different environments, conditions and time, we selected a few reports to analyze as follows:

Case Study #1

In this case, there was high concentration of coolant contaminant, no wear on elemental analysis and a positive glycol presence on a Komatsu PC490LC-10, 15W40

The analysis indicates a critical level of contamination is present. The water content and the coolant additives concentration are high. The glycol test is positive, which represents a likelihood of coolant loss or unusual required additions. A coolant pressure test might confirm the location of the leak or source of coolant intrusion. The infrared test and the viscosity test were affected due to sample condition/contamination.

No wear was detected by elemental analysis, meaning that the severity of the damages on the unit still remain under control, but the degradation of the lubricant is excessively high. The data provided indicates the oil and filter were changed at sampling. Due to the level of contamination, an additional drain and/or flush may be required. Resampling was recommended after diagnostics and corrective action to confirm improved conditions.

Case Study #2

In this case, there was high concentration of coolant contaminant, no wear on elemental analysis and a positive glycol presence on a Cummins ISLG-, 15W40.

The analysis indicates significant coolant additives are present. The wet chemical glycol test is positive, confirming antifreeze contamination is present. A cooling system pressure test and an inspection is required to verify the leak and to locate the source of contaminant entry. Continuing operation without correction of the leak will advance lubricant degradation and accelerate component wear. For this reason, the sampling is repeated with notable frequency to closely monitor the contamination and the degradation of the lubricant without compromising the integrity of the component.

Case Study #3

In this case, there was high concentration of coolant contaminant, wear on elemental analysis and a positive glycol presence. Immediate corrective action and resampling were recommended on the Komatsu D61PX-23, 15W40.

The analysis indicates critical conditions on water and coolants additives contamination. The glycol test was positive, confirming antifreeze contamination is present. A cooling system pressure test and an inspection are required to verify the leak and to locate the source of contaminant entry. The silicon present may be wholly or partially coolant additives. Wear might be generated due to the corrosive action of the contaminant and is generally associated with cylinder area wear. The lubricant degradation is caused by the contaminant as well as combined with possible high temperatures due to the cooling system ineffectiveness or overextended oil operation. Drain, flush and refill the system is highly recommended. Resampling after diagnostics and corrective action were performed to confirm improved conditions.

The analysis indicates critical conditions due to excessive coolant and water contamination, which affects the viscosity. The glycol test is positive, confirming antifreeze contamination is present. A cooling system pressure test and an inspection is required to verify the leak and to locate the source of contaminant entry. The silicon present may be wholly or partially coolant additives. All contaminants might be residual from previous events. The data provided indicates the oil and filter were changed at sampling. Draining, flushing and refilling the system are highly recommended. Resampling after diagnostics and corrective action can confirm improved conditions.

Case Study #4

In this case, there was high concentration of coolant contaminant, wear on elemental analysis and a negative glycol presence. Immediate corrective action and resampling are recommended on the Komatsu PC490LC-10, 15W40.

The analysis indicates abnormal conditions due to coolant contamination, but the glycol test is negative and other contaminants were not detected on last analysis. Previous wear might be generated due to the corrosive action of the contaminant and is generally associated with cylinder area wear. Monitoring the coolant system for loss and/or unusual required additions is recommended. The data provided indicates the oil and filter were changed at sampling. Draining, flushing and refilling the system are highly recommended. Resampling at half the normal interval should be performed.

The analysis indicates abnormal conditions due to coolant contamination, but the glycol test is negative and other contaminants were not detected in the last analysis. Previous wear might be generated due to the corrosive action of the contaminant and is generally associated with cylinder area wear. Monitoring the coolant system for loss and/or unusual required additions is recommended. The data provided indicates the oil and filter were changed at sampling. Resampling at half the normal interval should be performed.

As you can see with the case studies shown, the two methods reviewed for interpreting whether glycol contamination is present have a symbiotic relationship. They can be used independently, but you need to be aware of the limitations of both of them when opting to use one or the other in diagnostic practices. Using elemental analysis by itself can lose the visibility of possible diagnostic information on the source of the leak. Using the colorimetric option by itself leaves you vulnerable to problems with that test used in conjunction with modern, hot-running engines producing false negative results, as well as loses severity visibility. If used in conjunction, you stand the best chance of improving your reliability program in regard to complete data on coolant-related problems in your engines.