318i M40 front crankshaft oil seal

[madiran]

Does anyone here have any practical experience of changing the front crankshaft oil seal on an M40 engine? In particular the removal of the crankshaft bolt. The BMW tool 112170 as recommended by the Haynes book blocks the flywheel ring gear and can only be used with the engine out or gearbox dropped. I have the camshaft locking tools which include the crankshaft locking pin, does anyone know if this is sufficiently strong/safe enough to block the crank, given the high torque that the bolt is set to? There is a tool that bolts to the front of the crank with the hub removed and rests on the chassis, presumably the cambelt will have to stay in place to keep the engine timing whilst the bolt is initially 'cracked' then re torqued. I lean towards blocking the crankshaft at the front and employing a knuckle bar with a meter or two so extension. An impact wrench could be used but it needs to be powerful and I have heard of bolts snapping or rounding off using one. So, anyone have a tried and tested method? (that doesn't include putting the car in gear, getting someone to stand on the brakes and then firing the starter)