MAIN ENGINE – EXHAUST VALVE CAGE LUB OIL ‘O’ RINGS DAMAGED :
Machinery Break down :
The incident took place in one of our vessel after the dry docking repair. Port M.E was prepared and blown through with air after the dry dock routines. While blowing through, found Lub oil coming out of indicator cocks of no. 2,3 & 4 units. Soon after noticing the L.O., engine trying out was suspended and, inspection carried out to find the causes. Turbocharger drain was opened and also noticed L.O. coming through it. It was first suspected that the T/C sealing may be leaking and subsequently T/C was inspected and the exhaust connection between the T/C and exhaust manifold was removed & visual inspection of the trunking carried out and L-O was noticed in the trunking.
It was suspected that one of the piston crown might have cracked, allowing the L.O. to come into the combustion space. Therefore the suspected units leads were lifted & piston crown inspected. But no crack was noticed. Finally it was found that the rubber o’ rings of the exhaust valve cages had become brittle and cracked, thus allowing the L.O. from rocker gears entering into the exhaust v/v and to the units. The exhaust valve was pulled out and rubber rings renewed. All the units boxed back and engine prepared the defect was eliminated.