My friend is flying YYZ-MIA today and was supposed to be on AA1409 at 6:15am. He texted me at 2:00pm saying there was engine trouble and that they were still waiting. he then said he was put on the 2:40pm to MIA on AA, and that his 737 had been removed to a remote spot of the terminal. Apparently they tried to depart twice but both times they were boarded, starting taxiing out, and then turned back. Pilots said it was due to an engine problem. As far as I know the 737 is still at YYZ.
Anyone have any info on what caused such a severe delay and what was wrong with the engine?