Marcos Thadeu Lobo
Mechanical Engineer Graduated from the State University of Campinas (Unicamp). He currently works as an Associate Consultant at the company QU4TTUOR CONSULTORIA.
Interpretation of analyzes in lubricants
Interpretation of analyzes in lubricants – Physicochemical analysis of crankcase lubricating oils are used to evaluate the service condition of crankcase lubricating oils and that of internal combustion engines Diesel Cycle/Otto Cycle 4T, with adequate collection of crankcase lubricating oil samples of fundamental importance, if we want to obtain valid results.
Figures 1/2 – Lubricating oil and engine service condition
Valid samples are those that represent the service condition of crankcase lubricating oil and internal combustion engines Diesel Cycle/Otto Cycle 4T and should preferably be collected in places of turbulent flow and at operating temperature.
Figures 3/4 – Sample collected in turbulent flow and at service temperature
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CRANKCASE OIL SERVICE CONDITION CHANGES |
PROBABLE CAUSES |
| 1. SOOT | “RICH” MIXTURE (EXCESS FUEL), VERY EXTENSIVE CRANKCASE OIL SERVICE INTERVALS, AIR INTAKE SYSTEM RESTRICTION, ENGINE OVERLOADED, EXCESSIVE CLEARANCE BETWEEN SEGMENT RINGS AND LINERS, EXCESSIVE CLEARANCE BETWEEN VALVE STEM AND GUIDES. |
| 2. THERMO-OXIDATION | HIGH OPERATING TEMPERATURE, SEVERE SERVICE CONDITION, VERY EXTENSIVE CRANKCASE LUBRICANT OIL SERVICE INTERVALS. |
| 3. WATER AND GLYCOL | COOLING SYSTEM LEAKS, LOW WATER CONTENT (ppm) INDICATES CONDENSING WATER, IMPROPER STORAGE OF CRANKCASE LUBRICANT OIL. |
| 4. INCREASE IN KINEMATIC VISCOSITY | RISE IN SOOT CONTENT, ACCELERATION OF THE THERMO-OXIDATIVE PROCESS, REPLACEMENT WITH CRANKCASE LUBRICANT OIL WITH A HIGHER GRADE OF VISCOSITY. |
| 5. DECREASE OF KINEMATIC VISCOSITY | FUEL DILUTION, VISCOSITY INDEX IMPROVER SHEAR IN MULTIGRADE LUBRICANT OILS, REPLACEMENT WITH LOWER GRADE CRANKCASE OIL. |
| 6. DECREASE BASIC NUMBER (BN) | DILUTION BY HIGH SULFUR CONTENT FUEL, REPLACEMENT WITH INCORRECT CRANKCASE LUBRICANT OIL (LOWER BASE NUMBER – BN), EXCESSIVELY HIGH CRANKCASE OIL SERVICE INTERVAL, MISLEADING OIL SAMPLE, USE OF HIGH SULFUR CONTENT FUEL. |
| 7. SULFATION | DILUTION BY FUEL WITH HIGH SULFUR CONTENT, USE OF FUEL WITH HIGH SULFUR CONTENT. |
| 8. FUEL DILUTION | LEAKS IN FUEL SYSTEM CONNECTIONS, FUEL TRANSFER PUMP LEAKS, INJECTION SYSTEM FAILURES (INJECTOR PUMPS, INJECTION NOZZLES ETC.). |
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