Never had this happen before - Just need to whip an old n/a engine out of a defender so I can change the rear oil seal. It's a low mileage early defender, very 'original' so was expecting a bit of a fight, but didn't expect it to win! So all pipes/cables etc removed, all bellhousing nuts removed, hoist on - big heave - nothing 30 mins of effort later and still no sign of the joint splitting. Plusgas round the joint, blowtorch all round the bellhousing to release any sealant. Finally tap