i have a late serial number case 450 w/207 diesel. 1900 original hours, one previous owner used machine for finish grading residential construction. the engine starts unbelievably well, even after sitting for months. it has new injectors. i feel the engine runs "sloppy". it blows some black smoke under acceleration; in neutral or when turning the tracks. it is "skippy" at high idle, and blows a black/grey smoke. it does not have the power to steer itself when going up hill, it labors to move itself uphill in a straight line,. it gets to the point it just stops moving with the engine revved up and spewing a haze of smoke. i am not sure if it is revving up as high as it should/could. it has functional gauges that seem to indicate pressures are good. the dozer "rolls" well on its tracks; i have no problem pushing it around with a 40hp tractor. brakes dont work, so nothing is dragging. does this sound like a drive problem, an engine problem, or both?
Check air filter
Have your tried checking or adjusting the inj. pump timing??
Do you have a tachometer? what rpm does it rev to at high idle, and what does it drop to under load stalled going up the hill?
Sounds like your torque converter is slipping, what is the trans pressure when it's cold and after it warms up?