CONFIRMATION OF DIAGNOSIS DIESEL MAIN ENGINE / VALVE CLEARANCE CONCERN

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 of Zamil 58 ship. A Hi, Raw, Ultra vibration and PV measurements were performed with our equipment, the results were then analyzed.

1 INTRODUCTION

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 DEVELOPMENTS

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 cold engine for exhaust valve clearance should be 0,5 [mm]. The exhaust valve clearance was adjusted.

4 REMEASURE

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 the all the valves are closing at the same moment.

5 CONCLUSIONS

It can be concluded that the diagnosis obtained from the measurements and the data analysis was correct.