Cracked crankshaft

If your engine was a 1lw prefix they did or should I say some did have a tendency to break cranks. Luck of the draw really. Sucks thou.

 

The 1lw and 5ek and 6ts engines had crank issues. With the mileage on it I will bet the damper is original. And that caused the break.

 

Many things can go into that like others have mentioned. My first thought is harmonics. To the best of my understanding the rotating mass can create tones as when you strike a tuning fork however it is out of our hearing range. These can brake a crank as an singer can break a glass. Both of these sound far fetched to most people but why is it a harmonic balancer? No its a torsional damper? Maybe dual purpose with the same end result?
Why does Cat tend to use insulation covers on oil pans and front covers? Keeps kitty warm in winter and cool in summer? No they help control acoustics to reduce harmonics.
Incorrect chamfers on oil holes and the end of journals (actually a fillet) are common causes of failure.
A crank that has any extra bearing clearance can have exaggerated level of failure without loss of oil pressure.
Some cranks are really tough like a Cat 3304 can get .050 under rod bearings. Others have no room for margin like an 8.2 (?) JD. No under size bearings are available even from the aftermarket. From other posts sounds like you may have one with no room for error.

 

From my understanding it was bad machining on the fillets that caused these failures.
I think a lot of people fail to realize the importance of the damper on the crank.
They should be replaced like a service part but often get ignored.

 

How much "end play" ?

 

I HAVE A PETERBILD WITH A DETROIT ENGINE JUST OVERHAUL AND THE DIESEL IS LEAKING INTO THE OIL,
BISIDES THE INJECTORS WAHT COULD BE ANY OTHER CAUSE OF THIS

 

Inna swing in the dark here, but your piston rings may be leaking diesel from the cylinder into the oil pan.