Can you replace Crankshaft on a Chevy cavalier 2.4l without removing engine?

No...The problem comes in with the bolts that hold the flywheel onto the crankshaft. You just cant get to them with the tranny still mounted. And then at the other end,you have the timing chain. And in the middle (inside the oil pan you have the chain that drives the oil pump. Also...cleanliness is a big factor....pulling the engine and tranny as a unit out the top is not that difficult, but it is designed to come out the bottom. All the plugins are different..remove the crank pully, the intake manifold(so to give more clearance for the exhaust pipe to clear the "arm" part of the tranny in the back part of the engine), the tranny mount from the car(driver side) and bend the corner of the battery tray alittle. Then peel back the brake master cylinder without removing any brake lines... It comes out without any problems.