I recently attended a site to investigate an MTU 12V2000G23 generator engine.
The call came in because onsite personnel had found oil leaking from the dipstick tube and filler tube during a test run – they immediately shut the engine down.
Once the engine was shut down, they identified that the auto top-up oil tank was empty, and concluded that the valve had failed, allowing the contents of the oil tank to empty into the engine sump.
Taking action to rectify this, site staff removed approximately 90 litres of oil from the engine to bring the level back to the maximum mark of the dipstick.*
*For reference, the engine normally holds 77 litres.
They attempted to bar the engine by hand, but it would not complete a full revolution, leading them to suspect there was a hydrostatic lock present in one of the cylinders.
After these initial actions, we were called in to assist.
My first step was to carry out a borescope inspection of each cylinder to check for damage.
I removed the air inlet manifold to gain access to the injectors, and found oil, indicating that oil had passed through the complete air inlet system – due to the configuration of these engines, it is not surprising that oil was found in the inlet manifolds.
Once the crankcase fumes have passed through the breathers, the fumes are directed back into the inlet side of the turbochargers to be burnt in the engine.
The breathers are designed to filter out any oil droplets in the crankcase fumes, but when the engine is overfilled to this extent, the breathers are unable to cope with the amount of oil, and oil is passed back into the inlet side of the turbochargers.
Thankfully, during my investigations and the removal of oil from the air inlet system, no damage was found to any engine components and once started, the engine ran well, although the exhaust was quite smoky.
This was to be expected as all the engine internal surfaces were coated with oil. This smoke should clear when the engine is put on load.
The operator was advised to ensure they carry out pre-start inspections.
This will highlight issues such as the oil top-up tank being empty, allowing the appropriate action to be taken before engine startup.
This attendance shows that although items may be ‘automatic’, they still require periodic maintenance and attention. A simple oil level check before starting the engine is invaluable and can save you both time and money.
