Why are rodents building nests in my car engine?
Mice and squirrels exploit warm engine bays to stash insulation, leaves, and food items like acorns or tortillas, creating hard-to-reach blockages. This nesting debris leaves car owners stuck with expensive wire harness repairs and afraid to clear out tangled branches for fear of breaking mechanical parts.
What the numbers show
Counted from the threads quoted below. How we count
- This comes up 10.6× more often in r/MechanicAdvice than across the site as a whole.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Placing bars of Irish Spring soap in the engine compartment
- 2Cleaning the engine bay thoroughly to remove nesting materials, waste, and scent
- 3Spraying peppermint essential oil regularly in the engine bay
- 4installing an underhood animal chaser
- 5spraying the engine bay with natural deterrents like peppermint oil
- 6leaving the hood propped open when parked
- 7pouring chili powder or mixed chili powder water over the engine bay
- 8using rodent repellant sprays
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“I removed some of the branches but others I’m afraid to remove because they are lodged in some of the mechanical stuff, I don’t know how to get them out without breaking something. I’m also wondering if maybe a small animal like this squirrel is trying to build a nest in there??”source ↗
“This just happened to me, paid about $600 in wire harness repairs.”source ↗
“I had the same problem under my hood, but they weren’t bringing in sticks and what not, they were bringing in those acorn looking things and then stepped it up to a freaking softshell tortilla.”source ↗