MAIN ENGINE CONTROL AIR SUPPLY FAILURE :
Auxiliary Engine - Non Stopping Of The Lubricating Oil Priming Pump While Servicing :
This incident happened onboard a product tanker’s auxiliary engine. During the regular testing of monthly performance one of the auxiliary engines it was noticed hat no 3 unit peak pressure was high abnormally and also the exhaust temperature. So it was decided to check the fuel valve first. The fourth engineer, who was in charge of generators, replaced the fuel valve with a overhauled one. These fuel valves were lube oil cooled (Sulzer generator). After making all connections, the aux. engine was started without blowing through the engine. The engine over sped causing irreparable damage to the engine frame by breaking all connecting rod bolts. The pistons broken and flew out of engine.
During investigation, it was found out that the lub. oil priming pump was not put off from auto mode and it has filled up the unit while the fuel valve was removed for replacement. The lub. oil has found its way to the air cooler through the open inlet valve. When the engine was started, the engine was filled with lub. Oil and so the engine did not stop on over speed cut out.