MANUFACTURING PROBLEM :
(Main Engine fuel pump)
On one of the vessels the main engine had problem while maneuvering in DO while it was behaving alright an F.O. It was an SMC engine. The problem had been there for over a year. Every thing was tried from changing fuel v/vs, fuel p/p delivery valves, plunger / barrel lapping sealing surfaces etc. Mean while one of the sister vessels which had a similar problem was developing the starting problems in F.O. also.
The problem was finding time out at sea to change over to D.O. and try out the engine to see the effects of our experiments and immediate action was limited to sea conditions and the time that could be saved doing additional / extra speed over and above what was required by the charter party.It was only incidentally that once M/E was stopped in F.O. unit 4 Fuel pump was opened up. Found a crack on the inside collar of the p/p where the barrel sits, the crack was visible only because it was highlighted by F.O. the same way a D.P. test reveals.
This crack had been venting the oil (diesel oil) to the casing and there was no pressure build up / injection since the rate of pressure and quantity of oil metered for injection were both low at the starting speed of 35-40 rpm. Out of interest, other units’ fuel pump were also inspected and found similar crack in units 1 and 6.
The inference was there could be manufacturing defects even in parts well designed developed by reputed manufacturer. The manufacturer was informed of this finding, though there was a reluctance in the beginning, they agreed and replaced the pumps at their cost.