CM2250 Swap with CM870/871

[tariqzai]

(04-20-2020 )Rawze Wrote:  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.

Thank You Rawze, I bought this truck used in 2018. Its 2012 kw T660, 500HP and I believe 1850 Torque, 3.55 ratio 18 speed about 850K miles now. Truck max speed is 71/mph governed, loads are mostly 78-79k with reefer trailers go anywhere except CA, driver runs it mostly around 1500-1600 RPM.
Cause of engine failure; Head on this engine was replaced by the previous owner as well (Well known renting/leasing business). Truck was leased to a metal company and I believe they were hauling heavy loads, most probably it had the liner problem back then and was not checked by their shop so they might have just replaced the head and gasket. I think my mechanic said the liner on Cylinder#5 dropped down .05 from the adjacent cylinder on the passenger side of engine and he thinks it's more than what cummins recommends. Mechanic is an honest old man with decades of experience, lacking on knowledge about emission issues though.
Reason for Cheap fix; This truck will be in the fleet for at most another 2-3 years, I have the same make donor truck with CM871 engine/filters/wiring and hardware, costs me only 3-4k in labor to finish the project. CM871 has 500HP and 700k+ miles and should last for another 2-3 years.
I had problem of pushing coolant with one of my truck in the past and I got the engines swapped and turned out very cost effective but back then both those engines were CM871. I did not know about the complication of getting it registered as glider truck since the swapping engine is older now.
I am going to get a $$ estimate on replacing head/counter bore and inframe kit. Do I need to get an OEM head or the same head getting rebuilt from shop will work?
Thanks you for your advise Rawze, will update you.