Wondering if this is generally a good engine, 1994 M11-310? Seemed to run good with no smoke except a puff of black on start up.
We had a truck with an M11 in it, and it almost spent more time in the shop having the engine replaced than it did on the road. The truck was on it's 13th engine when it was traded on a new T800 with a Cat engine at 3 years old. Before anyone asks, every engine was a warranty claim. Several never even made it out of the dealer's shop after having the engine replaced before they grenaded. I'm not a fan of the M11.
I have a favorable opinion of the M-11 and its successor the ISM. Bad injectors causing a miss will be the most often encountered problem. In Louisville trucks, oil leaking out of the rocker box to head gasket is a surety, with the 20 degree turn it puts about a quart or so of oil in a puddle that can't ever drain back to the oil pan. The flywheel housing can also be a weak link if a heavy trans without a good rear support is used. Over time, the weight cracks the housing at the bottom making a leak that looks like a rear main, but it's coming out of the housing cracks. These motors are routinely seen at 370hp so a 310 is safely in range. They have a few issues but what doesn't? Knowing what you're up against is the key.
It's in 1994 L9000 that used to be a plow truck. Engine looked pretty clean and had 70 PSI oil pressure.
I have a m11 in a 98 Freightliner. It has been very good. Never any major issues. Biggest problem with Cummins seems to be oil leaks. Had to do the front cover on mine this year. These motors don't usually run high oil pressure. Mine on a hot day will only see around 36-38 psi rolling down the road. Motor has around 380,000 miles.
I have 2- in different trucks both around 370 hp and have been very good overal with very few issues