It is possable but a lot of work. You have to remove the gearbox, clutch, rear engine mounts, clutch housing, loosen exhaust at manifold, remove top hose then lower rear of engine. you can then do it. Or remove engine . When the core plugs are removed use a peice of stiff wire and loosen of all the sediment from around the rear cylinder liner then flush out with a hose pipe. All in all best to remove engine and do the job properly