[screamingchief]

I can easily see some excess heat (ie: blue'ing) in the area of the break around that rod journal/counterweight.

My WAG,it spit the OP shaft outta it,then it obviously lost oil pressure,rod grabbed the crank,bam broken crank,only odd part here is the OP says the rod bearing itself looked ok.

Was the big end of that specific rod discolored @ all???

That discoloration is away from (opposite side of) the main journal that has the thrust bearing on it,but despite that (one way or the other) I feel that the thrust issue could be the root cause of the crank breaking here.

Now were that the case,how about this chain of events,in this scenario the excessive thrust could easily be what took out the OP shaft,that's a no-brainer,that back counterweight is like right there,so that seems easy enough to see happening,I just dont think we'd see that obvious heat discoloration if the shaft jammed in there and caused the crank to break.

And the dowel pin is sorta the same deal.

I mean you can clearly see that specific main cap was fretting,and that's likely why the dowel fell out.

I dunno,looks to me like a couple of different things were going on @ the same time here.

Thrust is all outta whack,crank is sawing back & forth in the block,that causes the cap fretting situation first,so yeah it drops the dowel outta there,eventually the rearmost counterweight takes out the OP shaft,instant loss of oil pressure,then bam a rod grabs the crank,and the crank breaks.

Just curious,what casting no. is this block?

If it's a 557 block,that might explain some of this.



Bret P.