300Tdi Exploded

[Finnius]

Hey folks,

What causes a 300TDi to throw a conrod through the side of the block?

Normal engine running temps. Well maintained. New bearings a few years ago. Normal oil pressure. On a reasonably flat road - loud bang noise, shuddering, three or four inch hole out the lower left side of the block spraying out oil.
I haven't taken out the engine and disassembled yet.

Is the only causes a bearing or bolt letting go and the conrod banging around by itself? Oil pressure prior was exactly the same as it has been for years. I have multiple oil pressure gauges (including low pressure alarm) and cylinder head temp gauges etc that has become habit to look at every day. No weird noises or anything peculiar prior.

Thanks for any thoughts!

[Blknight.aus]

same as any other engine.

fatigue failure of the rod, loosing the bearing cap, little end failure, bearing siezurepiston failure, cylinder failure (usually thats a linerfailure), crank failure....

[V8Ian]

Sounds like a big end, bearing bolt or cap failure, unless the rod broke.

[Mercguy]

typical contributors.
Big end, little end, piston siezure, spun bearing.

Rarely do rod bolts fail unless they were incorrectly assembled - overtorque is an issue with those who manually click thinking they have a better feel than a torque wrench with angle gauge.

but you're probably looking at an overheat situation - localised - probably the big end bearing on the rod decided it was going to take a holiday in the sump.

Anything else broken? top end bits?

[Tins]

300 TDis are generally robust engines. The suddenness of the failure, along with the normal oil pressures, suggests that Dave has it, a fatigue failure, possibly of a cap bolt. Mercguy suggest overtorque, which is poss. Trouble is, that huge rotating sledgehammer aka the crankshaft will likely have destroyed the evidence if there were any revs involved. The forces involved are immense.