29th Mar. 04

This incidence relates to a MAN four-stroke engine.

This engine is equipped with auto backwash filter on the lube oil line. It is a kind where LO passes through one filter at a time in rotation while the other filters are automatically back-flooded. Due to worn out liners, which were due to be renewed, these filters were getting choked quite often, necessitating the opening up and cleaning them manually.

The filter was a fine mesh type with a rubber gasket at the bottom for sealing. In this operation of subsequent cleaning, sometime during the process one of the rubber gaskets slipped and fell inside and got carried into the engine.

This piece traveled through the main bearing into the journal pin, through the bottom end passage and blocked the oil flow to the piston and got stuck in the w/r valve of the connecting rod. This led to the piston running hot, and scrapping of the liner.
hindustan institute of marine training chennai