New CM870 long block

[Rawze]

is it a certified cummins OEM reman long block?. or one that was built at a shop and sold?.

Was the muffler changed?. .. old trucks with CM870 engines have mufflers, and they do get restrictive over the years due to soot buildup in them. A restrictive muffler can lead to improper fuel-air-mix, the turbo not spinning up as well as it should, smoke issues, and fuel mileage / power issues too.


and yeah .. sometimes the engine needs some miles and run time on it to make it stop smoking after a rebuild. As an example, my CM871 took almost 80,000 miles to fully break in after I inframed it.