Fuel Dilution of Engine Oil in Mining Dozer
Including routine oil sampling and analysis is an important part of your maintenance strategy. Detecting and resolving problems before they lead to costly repairs, complete failures or unplanned downtime are the primary goals of any oil analysis program.
Background
As part of their planned mid-life maintenance program, this oil sands mining company overhauled the engine of a large mining dozer. Upon returning to work, maintenance and condition monitoring best practices were followed including a 100 hour initial oil change and routine oil sampling. For this particular unit, the engine life expectancy was 14,000 hours and it had 7,818 hours (56%) of its engine life consumed.
The Situation
The engine oil was sampled 3 weeks after the initial oil change. The results indicated there were large amounts of diesel fuel present in the engine oil beyond what would normally occur from extended engine idling or typical unit injector leakage.
Recent work history showed that Technicians had visited the unit the previous day for intermittent low engine oil pressure alarms. However, the team found nothing abnormal at that time. An alert was issued and the unit was brought into the shop for further investigation.
Actions Taken
Upon more thorough review in the shop, it was determined the root cause of the fuel contamination was multiple failed fuel injectors on the right cylinder head. Routine sampling helped to alert the team to the issue early before any significant engine wear or damage could occur. Fortunately, the unit was still under warranty which covered the majority of the repair costs. As well, because the issue was caught before any secondary damage occurred, downtime was kept to a minimum and no other engine components required repair or replacement.
After operating another 4,000 hours and approaching its replacement benchmark, the engine continues to show no signs of bearing or cylinder wear on follow up samples.
The company saved nearly 50 repair hours and avoided significant engine replacement costs due to their diligence in conducting routine oil sampling and prompt investigation into the issues identified by the results.