I was being a good son over the weekend cutting down some of my mom's overgrown trees and my chainsaw seized up on me. It's an 18" Craftsman and since I don't use it very often, I didn't check the level of the bar chain oil. The chain gear stopped rotating and that's when I realized that I had ran it dry. After I added oil, I was able to turn the gear manually with a wrench, but it won't rotate when the engine is running.

Is this repairable?

 

Sounds like the bar is shot and the chain probably is as well.

 

Before you give up on it, squirt some liquid wrench or power blaster the whole length of the chain then then try it again, you have nothing to loose, just be carefull. I saw a utility crew out on a job, and they had no bar oil since the start of thier shift, I gave them some pretty good drained oil, and the saw sounded a little better, and I guess they made it through the shift.
Sid

 

Shouldn't I be able to isolate the problem by removing the chain and bar and starting the engine? It's not rotating when they're off.

 

As far as oiling it and working it loose, you might get it to come loose again, but usually when one gets run dry, it overheats badly and the parts lose their temper, the bearings in the roller tip go bad, and the chain gets too much play in the links and may come apart while in use. Replacement is the best option.

What exactly isn't rotating when the chain and bar are off? The drive sprocket on the crankshaft? Is the clutch turning?