E46 crankshaft failure

[rb51]

just posting to see if anyone has come across this problem with m47 320d engine or am i just the unlucky one?

[TheEnd]

I havent heard of that before, what went wrong? a bearing?

The e46 M3's were the only car i can think of with a crank issue

[rb51]

to start with the engine started to knock slightly but only between 1500 and 2000 rpm after a day or so the clutch pedal started to jump slightly when being pressed so assuming it was the dualmass flywheel beginning to give trouble i drove away on it,A week later the noise was getting very bad tick over now the worst so i ordered a clutch and flywheel kit and pulled the gearbox out removed the clutch and flywheel and put in the new kit i put the box back in and started up the car but as you guessed it started tapping,so next plan of action remove sump which i did (balance unit ok) so i turned to the big ends all ok except no 4 which not over bad was scoured i also checked the mains all seemed normal so i got a new set of big end bearings and put the lot back together turned the key and yet again rattling and tapping,engine out time next still totally puzzled to the source of the noise except that it was coming from bottom end,i stripped down the engine removed shaft and was left looking at a bare engine block and a garage full of parts and still baffled to the source,
next day got shaft checked over and although it looked perfect there was a massive crack across the back of the big end where it meets the web of the shaft only visable when you pry the rear of the shaft how it did not break completly is beyond me anyway a second hand shaft was bought and all put back together all ok now,