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 11.1× 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.
Found another way around this?
Share your steps and trade-offs so fellow engineers don't have to reinvent the wheel. No account required.
Why are rodents building nests in my car engine?
- 1Placing bars of Irish Spring soap in the engine compartmentDid this help you?
- 2Cleaning the engine bay thoroughly to remove nesting materials, waste, and scentDid this help you?
- 3Spraying peppermint essential oil regularly in the engine bayDid this help you?
- 4installing an underhood animal chaserDid this help you?
- 5spraying the engine bay with natural deterrents like peppermint oilDid this help you?
- 6leaving the hood propped open when parkedDid this help you?
- 7pouring chili powder or mixed chili powder water over the engine bayDid this help you?
- 8using rodent repellant spraysDid this help you?
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 ↗
Where this came up
People with this problem also raised
- 3How to clean a mouse nest out of car vents
- 2How to find an ant nest in your car
- 2Can I relocate an unreachable engine ground cable?
- 2How do I remove debris from my car engine bay without breaking anything?
- 4How to encapsulate a dirt crawlspace yourself
- 4How to keep mice and rats out of your outside AC unit