I was installing a new exhaust head pipe on my Ford F-350. I had both arms buried in the engine compartment when I noticed 2 large beady eyes staring back at me. There was a pack rat living in the engine compartment of my truck. They are notorious for doing thousands of dollars of damage to electrical system. It happened to my neighbor. The previous owner left in the middle of the night and left garbage under the deck. A real idiot.
After some research I learned to raise the hood and keep a light on. I used evergreen boughs to discourage him. They access most engine compartments by climbing up the tie rod ends. I put a rat trap there. I trapped one in the yard and an owl got another one. Problem solved.