I used to have this dog that was a dyed-in-the-wool "outside" dog - you couldn't coax that dog inside the house with a T-bone steak! We had one of those plastic "igloo" dog houses for him out on the patio in the back yard.
One year we had an exceptionally cold winter - sub-zero temperatures. I felt sorry for the dog and thought he would appreciate a little extra heat, so one evening, when they were forecasting record lows, I got my trouble light with a 60 Watt bulb and rigged it inside the doghouse on an extension cord.
Anyway, about midnight or so, I hear the dog barking and howling. This went on for a few minutes, so I got out of bed, put boots and coat on, and went outside to investigate. I went out the front door looking for what was making the dog so upset, and I couldn't see anything but I smelled this odor of plastic burning. I walk around to the back of the house and there's his dog house with flames just rolling out of the igloo opening!
I had to real quick get the garage open, get the garden hose out and the outside faucet turned on, and make an aggressive attack on the doghouse fire. I was on the fire department at the time (retired now) and there was NO WAY I was going to call the fire department to put out my dog house fire.
The whole time the dog is giving me this dirty look like "OK, dummy! What are you gonna do now?"
But the moral of this story is: Be careful with the improvised crankcase heating techniques. They might work better than you anticipated.