Detroit pistons (5&6)

Most likely piston is broke between rings. But that is strictly guessing having not seen it. I would get it looked at by a reputable guy, even if you wait an extra week on him. Lot of people think they can inframe one. Very few do it and are done with it. Not all last either, course this is in some part of customer not wanting to spend more than planned. Rushing to teardown and order parts or preordering parts is another cause. Clean up and inspection of all parts to be reused is key.

 

The pistons do come out the top, but not through the liner. The liner, piston & rod come out together as an assembly. Detroit has a special cylinder kit removal tool for this since you can't use a normal liner puller with the piston in the way.

There's no way, I'd only re-ring. There is no extra labor to change the liners, they have to come out to do rings. You actually save a little labor because they wont have to clean and check out the pistons & liners for reuse. An extra $2000-2500 in parts seems like a lot now, but can you really afford to do it again later?

The other thing is the head. It looks good doesn't make me feel comfortable at all. Have it checked out and pressure tested. With the price of parts and labor, taking chances is not an option. Doing it right is always cheaper in the long run.

 

I must've not been clear. I never meant to give impression the pistons don't come out the top. I took mine out the top but not without the liner. It's the only way to do an inframe is out the top. I can't imagine any shop only re-ring the pistons either. Only doing a partial rebuild on an engine which has alot of miles would be alot of wasted time and money.
You Also can't use a normal liner remover tool.

14 liter is a good motor though.

 

I have a 2006 515 Detroit with 329,000 miles on it and have been using a gallon of oil a day in my quad axel dump ,for about 2 years , runs out good starting to smoke a lot now ,thinking I have the same problem as you , couple bad rings , had oil samples done they come back fine , just cant see spending $10,000 on the truck when I don't have it ,