Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

Can a nest around the engine cause huge fire?

I wrote in before about my Honda Civic catching on fire. Honda now claims that some sort of nesting material was packed all around the engine and in the exhaust, and it caught on fire. The Honda representative asked me how long it had been parked in a barn. I live in Milwaukee, drove it every day, always in the city! It was never in a barn! Honda says the nest looked like many animals had worked on it for a long time. I wonder if it was like that before I got it! I have only had it since October, and it was new. Like I said, I drove it every day.

The insurance company hasn’t told me yet what they think caused the fire. I have a hard time believing that a nest fire would cause the whole front end of the car to burn and become a melted mess. What do you guys think? Would a nest catch fire on a 70 degree F day after 15 minutes of driving? And even if it did catch fire, shouldn’t the engine be better insulated that it wouldn’t burn up like that? I am still convinced that there was a fuel leak from a faulty O-ring, like a bunch of other 2012 Honda Civics.

I guess it could, if the exhaust got hot enough and the mouse nest combusted. Once something under the hood catches fire, it is conceivable that wires fry, maybe short and the murphy’s law/rube goldberg domino effect applies.
There are things under the hood that can catch fire.

It’s possible. It can get hot, then the nest can catch fire, the fire causes a fuel line to melt (I did get a fuel line to melt. It appeared that a spark plug wire delivered just enough spark to cause the file) The fuel line used to install an inline fuel filter, was good old US made stuff installed on my Sunbeam, Imp.

Ask them to show you the evidence.
A car driven every day does not make for a good mouse nest. They will inhabit cars that have been sitting around but usually not something that’s driven every day. If that were the case, cars would spontaneously combust everywhere.

“Honda says the nest looked looked like many animals had worked on it for a long time…”

So, there must have been remnants of the nest after the fire, and Honda would have taken photos. If you’re dubious, ask them for the photos that show nesting material.

I would actually tend to believe Honda. It’s not in their best interest to leave cars on the road having that O-ring gas leak problem. They want those cars back so they can be fixed, so Honda doesn’t get sued for killing someone in a car fire. If your car had the O-ring problem, they’d want to know. If they did find a bad O-ring in your car, they would know to extend the recall to more cars.

And yes, animals like rats and mice do nest in urban car engines, so that’s entirely possible. Furthermore, once the nest material catches fire from a hot exhaust manifold, the small fire melts a gas line, and suddenly a small fire is a big fire.

So, you should try to satisfy yourself that Honda is being straight with you by asking for photos of the nest evidence, but I would tend to believe them.

Yes, a nest of any sort (rat, mouse, bird, or whatever) can start a fire and burn a car to the ground in minutes.

A quick look shows that Honda is recalling X number of Civics for a fuel line O-ring defect that could lead to a fire.
What I would do is first is find out if the VIN of your car is included in that Recall.

Since your car actually caught on fire and has become toast Honda Motor Company has a very vested interest in placing the blame on something other than a manufacturing fault.
This could lead to a legal push and shove and my first act would be to show up unannounced with camera in hand and demand to take a few pics of any alleged nest. Said nest could also be a moot point if the nest and everything around it is now ash.

Let your insurance company get to the bottom of this. My son’s inlaws had their Lincoln Town Car catch fire in the middle of the night. The car had been shut off for at least 6 hours and was parked outside the attached garage. The engine compartment caught fire and the flames jumped into the eaves of the house. The inlaws were out of the house for the better part of the year while it was being repaired. The car was a total loss–burned up to a cinder. However, the insurance company figured out somehow that it was related to a problem in the cruise control and the insurance company collected from Ford Motor Corporation for the damage to the house and car. The car was not under warranty at the time.

I would be interested to know what kind of nest and how they could surmise this if it was a major fire. If the car is driven daily I doubt that it’s mice. On the other hand some birds are extremely rapid nest builders. I remember when we were camping in a park in the northern Ontario it took them barely two days to complete a nest under the hood around the air intake in my Suburban. These were small birds of course but the material was definitely combustible and could have blown onto the manifolds if I hadn’t noticed it while doing my pre-moving on, fluids check routine.

Last fall, I had my 2011 Toyota Sienna back to the dealer for servicing. The service writer called me to tell me that they had found that some animal, probably a squirrel had been under the engine cover and that they had cleaned it out. When I went to pick up the Sienna, we left our 2003 4Runner for the dealer to do a recall. I asked them to check out the 4Runner to see if it also had animals under the engine cover. They told me that there was no evidence of it as there had been on the Sienna. Now, both cars are parked in the same attached garage and were parked in parking lots during the day at the same university. I have no clue as to why one vehicle was affected and the other one wasn’t.

@Sarah R
I certainly would agree that rodent nesting materials are ideal tinder, and in the presence of heat from the exhaust manifold or cat converter, it could ignite and initiate a catastrophic vehicle fire. However, I have a VERY hard time believing, as you do, that a daily driver would be subject to enough nesting materials to match the description Honda reported to you: “animals had worked on it a long time”.

Here’s a comparison. Two months ago I purchased a minivan which had not moved in five years. It had been parked outdoors in a rural area surrounded by high grass and underneath a few very large trees. The nearest building was at least 50 yards away. Rodent eating hawks commonly seen in the trees on that two acre parcel, which is surrounded by similar brushy, wooded, rural multi-acre parcels. So I’m not talking manicured suburban sprawl, rather this is older, dispersed, modest housing that is not routinely cleared of grass, brush, other woody debris. In other words, Prime Rodent Habitat. Yes, the engine room of my new ride was kind of cluttered with more fibrous materials than my daily driver, and I made only a haphazard attempt to clear it out. No fires to date.

Second example: I live on 3+ acres, you have to look hard to see another house from my driveway. I KNOW there are rats here…don’t ask. Deer live here-I see them every day. Raccoons and skunks are common. When I travel, one vehicle sits outdoors in a gravel driveway surrounded by grass, brush, and trees, most of which is never manicured…for a month or more. Two consecutive winters I was away for most of six months. No fires ever on the vehicle which remained parked in the driveway.

I could go on…my previous career had me living in an old farmhouse surrounded by a massive wild meadow outside Yosemite where we had regular rodent problems in the house. Some cars would not be used for several days, a week, a month, and no fires ever in any vehicles over decades of people occupying that house. Later, living in a cabin in a heavily wooded area near that meadow, no fires in cars that rarely moved.

This anecdotal information proves nothing. But based on that kind of context, I would be extremely resistant to accepting that your city based daily driver had rodents importing enough nesting materials to match Honda’s claims. I don’t doubt that rodents may have wandered into your vehicle from time to time, but to accumulate a lot of nesting materials overnight is just not realistic. If they can produce “evidence”, I suggest you consult with a university professor who specializes in rodent behavior, for an opinion. I think Honda’s claim is just not credible. Good luck!

I had some friends rebuilding a car with an engine that had been stored for while. They were assured by the owner ok to fire up and go. Double checked everything and the chipmunks had a stash of dog food in the exhaust manifold, A barn swallow built a nest in my friends boat exhaust wile in dry dock. A nest is not a long shot imho

In cooler weather, animals are sometimes attracted to the heat of an engine that has been recently run. Back in the fall of 1997, my wife and I attended a wedding reception. We arrived home and put the car in our attached garage. The door to the garage is always shut unless we are driving a vehicle in or out. At any rate, two hours later, I went out to the garage for something and a little black kitten went tearing across the floor. With a great deal of effort, I finally cornered the kitten and called my wife to come out with the pet taxi–a carrier we used to take our cat and dog to the veterinarian. We put a bowl of food into the pet taxi. The kitten gobbled it down and then cried for more food. She ate three bowls immediately. We know that the only way that kitten could have gotten into the garage was to have come in under the hood of the car. The kitten is still with us almost 15 years later.

Honda won’t show me the pictures, but I did see some burnt newspaper and leaves when the fire was put out. They said that the nest was all under the engine, too. I am sure the insurance company will let me look at their pictures after their investigation.

I never looked at the engine when I leased the car. I never even thought to look at the engine of a brand new car. I wonder if the nest could have already been there? I mean, the guy on the phone made it sound like this was a huge on-going project for a bunch of critters. What if it was there and no one knew?

I used to live on a farm. We had a mouse fly out of the exhaust thing on an old tractor once when we started it up, but we had no problems with things catching on fire. And some of this stuff was old and rarely used.

Oh well, I just hope I can get a new Honda Civic soon. I am obsessive-compulsive, so now I will have a new obsession - checking for nests. Does anyone know how I can check to see if something is nesting around the catalytic converter? I heard those catch fire easily. I keep imagining that my rental car smells like it is burning. I suppose I should see my neurologist…

Just FWIW. the ‘engine’ didn’t burn. It would require a furnace to melt/burn an engine. But the plastic ancillary pieces are expensive and when they melt they run into the engine and might require a complete tear down to clean out And, as has been mentioned, the wiring and electronics might be destroyed with even a small fire. I would be curious how a daily driver could get enough debris to do serious damage over night, though. It seems a stretch. But it is possible.

You’ve had the car since Oct, and it only takes a day or two to build a nest, so your 8 months of ownership was plenty of time for a critter to make your engine compartment his or her home…especially since most of those were winter months…and if you did see newspaper and leaves in, or coming out of, your burning/burnt engine compartment, that sounds quite consistent with an animal nest.

Now, looking to the future, I wouldn’t worry too much about inspecting your next catalytic converter frequently. Its shape is not conducive to building a nest on.

However, I do suggest that you become familiar with the location of certain important components under your hood and check them once a month or so…for instance, oil dipstick, windshield washer fluid container, radiator cap (open only when cold, never when hot), coolant overflow tank, etc…Open your hood once a month to check these fluid levels, and you’ll immediately spot any future nests. You’ll also become a more informed car owner and will be less at the mercy of whatever story an unscrupulous mechanic might try to tell you. And, you could save yourself expensive repairs by finding a problem (low oil, low coolant, etc) before it ruins your engine.

Thanks for the advice, jesmed! I didn’t realize all that needed to be checked so often. I wonder if the dealership will go through all that with me when the lease me my next car. If not, I will get my mechanic neighbor to help me. Next on my list is learning how to replace the sacrificial anode rod in the hot water heater…

When I had my shop a lady came in with her car on the tow truck. She drove it everyday and I had just did service to the week before. She had fire in the heater/blower box under dash. Luckily it went out on it’s own when she turned the car off. A mouse had build a nest in there. When she turned the heat on the resistor started the nest on fire. So its is possible.


Obviously you are the kind of person who never looks under the hood .

And speaking of nests under the hood: