Cracked and broken timing chain rollers were found during a routine inspection of the crankcase:
On carrying out a crankcase inspection of a MAN B&W MC engine, the above was found in the crankpit of No 2 unit. It was identified as a chain roller from the timing chain which had split in two.
The chain was inspected and 10 further rollers were found to be cracked on one chain only. The damaged links were replaced.
Procedure for replacing chain links
Grind off the riveted over metal on the pins that are to be pressed out.
A tool for pressing out the pins is placed over the chain link and the bolts for pressing out the pins are screwed in alternately until the link is pressed out. To remove one roller link, two pin links must be removed.
New links are then fitted with new pins and side plates, using a special tool to press in the pins which are then riveted over after fitting.
It should be noted that when changing links in a chain then the matching links should be replaced in the second chain to keep the chains at the same length.