Snowblower loud with black smoke
I have an MTD 2 stage snowblower. I recently had to replace the worm gear but now it works fine. This last time I started it it was really loud compared to what it normally is. Seemed to get even louder as I turned down the throttle. Everything still worked fine but after 5 minutes of using it it started spitting black smoke and I could tell it was about to die so I just shut it off. The gas is not old. What on earth could be happening? Worked perfectly fine last time I used it and now it doesn't? Thanks