This document consists of the detection and verification of a issue in the area of exhaust valves unit no 8 of a Bergen C25:33L9PY Main Engine SB with 48600 running hours. A Hi, Raw, Ultra vibration and PV measurements were performed with our equipment, the results were then analyzed.
The engine condition is based on vibration and ultrasonic measurements taken. The data obtained from the engine analysis was processed, analyzed and compiled by a qualified professional analyst, resulting in the following recommendation:
Exhaust valve clearance check.
2.1 THEORETICAL REFRENCES:
Early closing of the valve indicates a problem of excess clearance ore damage on the hydraulic tappets.
2.2 VIBRATIONS SHOWN
Exhaust valves Hi Freq Vib measurements acquired equipment can be shown as follow:
Vibrations on exhaust valve of unit no 8 are observed at 336°, much sooner than the other on the other units. As a conclusion of this analysis it was recommended to check the exhaust valve clearance.
3 SHIP ENGINEERS CHECKS
The engine was cooled down then the cylinder head no 8 cap was disassembled to access the rocker arm device. The clearance was measured by a feeler gauge and the clearance was found to be substantial. On a cold engine exhaust valve clearance should be 0,5 [mm]. The exhaust valve clearance was adjusted.
After the adjustment was made the engine was started and new measurements were taken the results can be shown as follow:
It is clearly shown that all the valves are closing at the same moment.
It can be concluded that the diagnosis obtained from the measurements and the data analysis was correct