Nut came off connecting rod bolt

D7 17A C Model -- serial no. 1701 -- motor started knocking, sounded like a connecting rod.
When we drained the oil, found a nut off a rod bolt in the bottom of the pan. Took the side
covers off and found the rod bolt laying in the pan slightly bent and it looks like it screwed
up the bolt hole in the rod, but the cap looks good. Looks very likely that there was never a
cotter key put in the castle nut. Bearing was scuffed up, but crank shaft doesn't appear to
be hurt. There was just a few drops of antifreeze in the pan. Could that be from a liner being
damaged? We can't see any evidence of where the antifreeze is coming from and it's a very
small leak. Maybe we will be able to tell where it came from when we get the piston out. Can
you take the piston out and put it back in without replacing the rings? The motor didn't take
any oil and ran like a top. It's a cryin' shame.

Where would be a good place to get a rod and cap for sure and maybe a liner and piston?
Don't know if Cat has that stuff in their nostalgic parts or not.

Before you pull it down any further, pressurize the cooling system and see if you can tell where the antifreeze is coming from. You will have the head off anyway to replace the connecting rod, the liner o-rings would be the next step. Might want to price a whole inframe overhaul kit vs just the repair parts if you go that far into it.

I would measure the crankshaft journal very carefully before proceeding with any of this. Would be a really bad decision to do all the work and the connecting rod bearing to fail again because the clearance was too much or out of round was too great.

Go through the balancer while your in there too.
Gary

I guess you know you were about 10 revolutions away from a cast-iron hemorrhage, right? Good time to shut her down...