Yep, fixed a Gleaner combine for a guy a few years back, engine wouldn't crank, and mice had eaten the wiring, repaired it and all was well. The NEXT day, he called and complained "no start". Went back and found mice had eaten through the repair I'd just made!
Mothballs in the cab and around engine work ok to keep them out. There is also a product called "Mouse Out". You spray it on a rag and leave it in the area you wish to repel them from. Many farmers use it around here, and report it works well.
I had the little f^&*ers eat through the plastic blower fan on my work car!
Andy
