A failed turbo seal causing blowby would not have a hard start issue, just blowby.
Did you remove the intake hose and inspect for dusting? Air intake system intact ? Intake hoses OK and not split? With approximately 5000 hrs on that engine if it is not dusted then I also would have to wonder what the maintenance was like on that machine. Everything performed at the proper intervals? What oils and filters were used?
Did the engine run smoothly or did it have a flutter sound? Misfire at all? That would indicate injector issues.
I also would not overhaul that engine without installing new injectors. With 5000 hrs on them they could be spraying improperly washing down the liners causing premature ring wear.
Not sure how maintenance was on it. I bought it about a year ago and have put 300 hours on it. When I bought it it had Baldwin filters on it. I have bought all Deere filters for it, and I did a complete service when it got here, and change the oil every 250 hours, fuel filters and pilot filter every 100-150 hours, I am religious about maintenance and upkeep. If I did rebuild it I would buy new injectors and have someone go through the pump. I haven’t seen any cracks or splits in the piping, it all appears new.
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