Hamilton's engine subsequently dropped from six to five functioning cylinders, and so the Brackley team asked him to retire in order to protect the unit from further damage.
"I was sent a photo of the part on the plane home on Sunday night," the team's engine boss Andy Cowell said. "It was pretty frustrating!"
Mercedes has subsequently changed the process with which the insulation is manufactured, after discovering that the original method often resulted in almost invisible cracks.
"Now the parts are made by injection moulding, which produces no seams," said Cowell.
He added that when the newly-manufactured parts were retrofitted to all the 2014 engines in the days after Australia, half a dozen seals with tiny cracks were discovered and discarded.
The engine used by Hamilton in Australia, now featuring a new seal, was fitted to the 2008 world champion's W05 for Sepang practice.
"Before we tested it, I was 90 per cent sure it would be ok," said Cowell. "After the sessions, I added a few more per cent to that."
Hamilton will continue to use the engine for the qualifying session - which was delayed for typically-heavy monsoonal rain - and the race on Sunday.