Any 8.3 Cummins wizards on here?

Before I bore with a long post just thought I’d ask if anyone knows these like the back of their hand. I’ve got a liner/liner o ring issue with one I need to pick a brain about

 

Before I go into the story, main question is, does the coolant seal off from going into the crankcase primarily from the metal to metal contact of the lower flange on the liner or is it sealed off only by the o ring?

 

So now the backstory. Engine was putting coolant in oil last year so suspected liner. Pulled pan and never found one drip. However, did see #6 liner had a chunk of o ring hanging down but swear on my life it never dripped once even with regulated air on system all night. Ended up finding crack in the head leaking coolant so figured that was smoking gun. Decided to go ahead and overhaul it while I was there though with that o ring hanging down and pistons had cracking. Got it running and same issue with coolant in oil (not bad but would steam and lose coolant slowly). Assumed crack repair didn’t hold so pulled valve cover and pressured and sure enough where they repaired crack was leaking again. So figured that was smoking gun number 2. So I drained coolant from head and pulled it. While waiting on it to show up I could hear a drip in the oil pan so decided to pull pan and check. Now #5 liner has a chunk of oring hanging down and it IS leaking this time. However, head is off this so no clamping on liners with it sitting there. I do plan to pull that liner and inspect but I guess I'm a bit curious why it didn’t leak before on #6 but is leaking this time on #5. I’m wondering if maybe with head on and torqued it clamps the liners down on the flange tight enough to seal metal to metal maybe? Thinking I’d read that in the manual but don’t remember. But also concerned why oring did that again in a different cylinder. Liner protrusion checked out when I put together last time and counterbores looked fine. It was a reliance kit which I’ve read a mixed bag of opinions on so maybe poor oring quality? Otherwise installation error possibly. Used oil for lube on o rings. Just looking for other opinions

 

Also, I don’t know if there were any different block styles but this is in an early magnum tractor so would be early 90s style one of the first ones

 

I’m also fairly certain it was not leaking before I pulled head because I had regulated pressure on it all night before I pulled it with bucket under oil pan and plug out and it never leaked any then either