He was hoping to beat the record held by Derry man Tommy Hughes who recorded 2.29.12 in the Nottingham Marathon in 2010.
McKinney ran very well and clocked a time of 2 hours 30 minutes and 50 seconds – and was 144th overall, but it was just outside the record.
He won the over-50 category with over eight minutes to spare.
Meanwhile, Twin Towns man Gary Murray, now 35, made his marathon debut and was on course for a 2.15 finish before he encountered some difficulties.
But he still managed a impressive time of 2 hours 21 minutes.
Murray was out of athletics from 2009 – 2013 and had two operations having been plagued by injuries.