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Rat dropping in engine compartment

Been having this problem for a few years off and on and it’s driving me crazy. I’m hoping I can get some suggestions or more insight.

Car and environment: 2013 Honda Civic, live in Canadian city, residential home, 2 car attached garage.
Problem: Rat droppings usually found in the engine on top of the transmission (bottom area of the engine compartment). Dropping also on the ground just under the engine area.

In the past year have trapped and killed 4 rats. Ranged from rather small to a fairly big rat. I know that the current rat is fairly big because of the dropping size. Have cleaned and searched all over the garage and no sign of rat or droppings. Only in engine and on the ground around the engine. Have set up traps around the garage and under the car. So far no catch for a couple of weeks but the rat is around. Each time I clean the engine of droppings and sweep the garage floor, no sign for about a day but soon after, it is back.

Searched and search as best I can around the engine and inside the car but cannot see any possible home. No damage to wiring or parts either. Opened up air filter and even using a shop vac to suck and blow air through and no trace of debris. Seems to be a clear flow through the air ducts.

Yesterday I make a very concentrated mixture on Pine Sol. Sprayed some around parts of the engine and rinsed it out. Wiped down most of the engine with this solution as well. Garage and engine now smell super Pine Sol fresh! This morning, no trace of droppings. Obviously, I don’t think this this deterrent should be a normal long term task. Any ideas where the rats hang out, where they might from? As said, I’ve cleaned and searched all over the garage and no trace of droppings or a home. There is no food sources in the garage at all. The only thing I can think of as a possibility is somewhere around the outside of the car the rats stay. Is this possible?

The final possibility is that they may come in from the outside through a couple of small gaps of the garage door. I plan to seal these gaps up soon. I’ve placed traps near this area and monitor the area but there is no sign they travel through this space.

Might be living under the battery tray, under the wiper motor, inside the air cleaner housing, etc.

Yeah, he’s probably living in the engine bay, that’s why you can’t find him in the garage

it’s a very common scenario

Have you thought about closing the garage door and then starting the car and letting it make carbon monoxide for a couple of hours while you leave the house.
The only problem is that now there will be a dead rat somewhere in your car or garage to stink up the place.

Irlandes in a recent post referred to some super sonic electronic rat repellent. I think they are only available in Mexico though but worth a try. Yeah, seal all leaks and keep door shut tight. Clean up any food such as grass seed. Get a big cat. Those suckers can live a long time without food or water though.

Trapping or poisoning the rats won’t work. At least not in the long run. There’s more or less an infinite supply; when you trap one, another will happily take its place on top of the transmission. To solve this problem you’ll have to make your garage rat-entry proof, which may take quite a bit of effort. Or find yourself a cat who will occupy the garage area. Keeping all food products, wrappings, crumbs, etc out of the passenger compartment and garage might help a little. But closing up all the rat entry points, that’s the best use of your time.

I have an ultrasonic pest repeller in my garage, that I bought…many years ago.
I originally bought it because Barn Swallows were trying to build their nests in my garage, and they were making a huge mess in the process.

In addition to that device ridding my garage of the Barn Swallow problem, I have not had the problems with rodents in my garage that most of my neighbors have experienced.
My next door neighbor had to have all of the wiring on his lawn tractor replaced after voles or mice, or…whatever…type of rodent decided to eat all of the insulation from the wires of his lawn tractor. I have had no problems of that nature.

I don’t think rat-entry proof is the immediate solution . . . but it may help in the long run

I believe the immediate problem is that the rat is living in the engine bay

Thanks for the comments everyone.

“db4960” comment about living in various areas inside the engine bay. I’m no expert nor a mechanic so my ability to take things apart is limited. The engine area is very clean. I see no signs of critters or garbage. Will try to take some pics if droppings reappear.

Any links to sites that might help me search for hiding spots? Some basic instructions on how to take things apart?

The rat might be living behind the plastic fender liner, for example

FYI . . . cleanliness has nothing to do with it

your engine bay is quite possibly a desirable place to live, versus the mean streets

The rats aren’t eating anything in your engine bay, and probably not in your garage. Leave the car out one night and put out poisoned food some distance from the house. Maybe the rate will go for the food and die outside. The poison I’m thinking of is the blood thinner that will cause it to bleed to death. It will stay outside to drink water, so don’t have any water available in the garage. Note that this poison will hur any animal. If you have cats or dogs that can get to the poison, you will want to consider that when you place the poison.

I wouldn’t advise doing what @jtsanders suggests, especially if other people in your neighborhood have pets. The neighbor’s pets can eat the poisoned rat, and by doing so get poisoned themselves.

I don’t think they can be living in the engine bay. They need food. Chase the food. My question is where else do you park, work/school etc.


I respectfully disagree

You probably can’t imagine how many rats I’ve seen LIVING in the engine bay, over the years

Try contacting your provincial (or territorial) agricultural office? Here in the US they have experts in rodent control whose services are free and I’m guessing they have these services in Canada too, it being as agriculturally based as it is.

I’m confused. Is this car ever driven on a regular basis? How can rats live in an engine compartment when the car is moving at speed, and makes stops? And may sit for long periods outside the garage?

And be totally invisible?

There’s PLENTY of hiding spots in a vehicle for a rat to hide

Wherever you drive, the rat’s along for the ride

I’m sure lot of the other wrenches on this website can/will agree with me

a cut and paste from a recent “Motor” article

The undercarriage of a recently
parked car is warm, dark and relatively
well protected from cats, so it’s an
attractive habitat for an enterprising
rodent. Air fi lters and various underhood
and underbody sound-deadening
insulation panels make for good
nesting materials. Rodents’ teeth
grow continuously, so to avoid becoming
tooth-bound they gnaw voraciously,
exhibiting an apparent preference
for hard nylon fuel lines and
small-gauge wires.

so there . . . food or cleanliness is not necessarily a factor

OK, I gotta go shut the garage door. Maybe take the shot gun along.

VDC, what brand of electronic device is it that works?

I had a rat living on top of the air cleaner. When summer came (to Albuquerque), it got too hot for him/her.

I would think the best place to put the poison would be in the engine compartment, that way other animals wouldn’t eat it, though some might eat the dead rat.

Warfarin (named after the Wisconsin Agricultural Research Foundation, not warfare) was developed for poisoning rats. It worked by thinning their blood. Rats and mice are always cutting themselves, but their blood clots quickly; warfarin makes them bleed out instead, a mess for you to clean up.

Warfarin is now the most common anticoagulant for human medicine; probably a lot of us use it; also called Coumadin.

We can make all sorts of guesses as to what the rat is doing and where it might be doing it, but your best bet is probably to call an exterminator.

Rodents have an amazing ability to get into places that you’d never guess they could possibly fit. If they don’t want to be found, you’re probably not going to find them unless you learn a lot about them first.

The rat might be living in your car, or he might be living under your garage cabinets and poking around in your car to see if he can find food or a place to store food.

I tend to not recommend poisons unless applied by an expert, because poisons that work on rats also work on pretty much any mammal including children and pets, so you don’t really want to be fooling with them unless you know what you’re doing.

I also tend to recommend against garage cats because cats will not just walk into the garage and kill the rat and then leave -they’ll also nose around all over the garage and knock things over and get into the antifreeze and kill themselves. Too many hazards to allow a pet to roam around in a garage unsupervised.

Time to call in a pest control expert.