CM2250 Swap with CM870/871

[Rawze]

Something does not sound right in your post to me. Possibly a mechanic blowing smoke up your arsse?. How far did the liner drop?. What did it measure?. What you describe sounds typical of only a few thousandths drop. There are hardened brass OEM 0.020" and 0.032" shimms avail for liner height corrections on the 2250's so that it can be counter-bored properly and this problem correctly and reliably repaired.

There is no way a liner suddenly dropped more than only a few thousandths before the head gasket went out. Even a 0.020" shimm is miles past whatever amount it has dropped. - If your mechanic does not know this, and the amoutn it dropped is actually only a few thou. then you best be finding a tow truck in a hurry and get the hell away from them, as nothing in that engine is likely to be re-built the right way after.

-- Sounds like the cheaper and most effective option just to fix it and go again for getting it back on the roads. Replace the head with OE, counter-bore it, overhaul kit, and go again ... Only when it is fixed,.. do it the right way so that it has its best chance to go another million on the inframe. Do all the recommended extra steps towards this ( some of those things are mentioned {HERE} ) and you will have invested your money much more wisely + get a far better return on it than simply slapping another engine in it.

- It likely can be converted over but ... Looks like your trying to justify a cheaper way out, but by the time you put all the effort and down time into the swap + straighten it out, your would have lost more money on it than simply fixing it in most cases. Not only that, but to make it legal, you will have to register it as a glider, have it emissions tested and have all the emissions systems for whatever engine you have used put on the truck too.

-- Lastly, you need to consider why it failed. -- Engines do not fail like that unless there is a reason. - Not solving the root causes is destined for you to repeat your mistakes that caused it to begin with, even if it is a different engine.

Some history on the truck/engine?, miles?, hp/torque rating?, rear ratios?, is it de-mandated (if so, by who?), type of freight hauling?, rpm range it is mostly driven in?, has it been driven right?- or are there hired drivers in it? -- etc.etc.etc.

Those are the things that come to mind (for me any ways) when reading your post.