We have 3 vehicles that a deviant chipmunk likes to stow walnuts in the exhaust pipes of each night in our garage. The last couple days in the mornings, we find walnuts in the exhaust pipes of all 3 of our vehicles. This morning I managed to pull 8 walnuts out of my Honda Elelment. The last 2 days we pull out as many as we can but we are fairly certain our Dodge Spirit has some down in the actual muffler because we kicked it and could hear both fluid and something clunking around inside. We also smelled what smells like burning paper/roasted nuts very strongly coming from 2 of the vehicles exhaust systems. We put some fine spun wire (like the old sos scouring pad material) in each tail pipe tonight after we parked each vehicle. We will have to take that out each day before starting the car of course. We have gone around the outside of the garage sealing any way we could see that the darn chipmunk might get in. But we still found nuts in the pipes last night. We are contemplating getting a pellet gun to kill it. Other than cutting down our prized English Walnut tree, anyone have other suggestions?
Also, and most importantly, will this cause damage to our exhaust systems of cars?
Reason we ask is because we had trouble starting our Mazda MPV about a month ago. It was a 92 with over 160,000 miles on it. We had AAA come jump it. They said it was our battery. But afterwards, we drove it to our mechanic to have everything checked because we had smelled a burning paper smell. After driving about 2 miles, it was smoking something awful out the tailpipe with a strong smell of burning paper (in retrospect, we realize it’s the same smell we are now encountering on our Dodge with the walnuts in the exhaust).
The mechanic could not figure out what was wrong and specualted the engine was gone bad after putting it through various diagnosing. The smoking continued and they recommended we not drive it anymore for fear it would eventually catch on fire. He left it up to us as to what to do with it, but suggested it be scrapped or we drop in a new engine. We figured we should just get a new vehicle and be happy it served us so long and for so many miles. So we decided to donate it to the NPR through the Car Talk Vehicle Donation program.
Now we wonder if the walnuts in the exhaust system wrecked our vehicle…or worse yet, maybe there was nothing truly wrong with it that cleaning the walnuts out of the exhaust (if we had known) would not have cured.
Advice would surely be appreciated, especially because we are worried about our new vehicle we got to replace the MPV is being damaged by Walnuts too.
When I first read the title to your problem I wondered if this was some sort of joke. Now I see you’re serious. I gotta admit, I never had this problem. (Who has!?) I can only give an opinion.
It would not bother me in the least to have a nutty muffler. Yes, I would do what you did and block off the tailpipe each night. No biggie. Then I’d ignore the extra baggage in the muffler and just drive. The chipmunk’s offerings shouldn’t hurt anything. Eventually the nuts would burn to ash and be blown out. No damage to engine.
If you are truly concerned, go to a muffler shop and speak to the head technician. He’d probably want to replace your muffler (rather than remove and shake out, which might or might not work). Let him do so. You’d have peace of mind.
P.S. – Let us know.
You guys are ambitious. Plugging and unplugging an exhaust every day? Try wrapping a piece of hardware cloth around the back of the exhaust. Gases passes; animals and nuts don’t. Red Greene would suggest fastening it on with duct tape. 
Hardware cloth held with a hose clamp sounds like a good idea. I remember in the mid 80s, my dad got a new exhaust on his 77 wagoneer, and the end of the tailpipe had a built in piece of perforated steel plate about an inch or so back from the outlet.
JMHO, but I’m a bit skeptical about an engine being ruined because of this. I could see exhaust heat causing walnuts to smoke, but I don’t see engine damage unless the muffler was packed so full that exhaust system backpressure was causing the engine to lose power and overheat. This would be very noticeable of course, and highly unlikely as the exhaust would have a tendency to blow most of them right back out.
It should have been a simple matter to remove the muffler and shake the walnuts out because they’re not going any further up the exhaust system than the first set of baffles in the muffler.
If this is going to be a continued problem then I would hose clamp a small piece of screen wire over the tailpipe rather than keep plugging it and unplugging it.
Or you could fence everything in and get a pet bobcat.
Sounds like your ‘02 was roasting walnuts. My guess is that the engine would have worked fine if you’d clean out the nuts. A good mechanic should have been able to diagnose a plugged exhaust system, and should also have been able to assess the condition of the engine and not have told you the engine was shot. Unless, of course, the engine in the ol’ '02 really was shot, which is a possibility.
I’d try putting some steel mesh from the hardware store over the ends of the tailpipes, securing it with hose clamps.
I doubt that the Chipmunks could’ve got the nuts past the muffler . . . it has chambers and stuff that would prevent them from getting in that far. But maybe. To be certain I’d buy a few muffler clamps and pull the last piece or two of the exhaust apart. You’ll know immediately if you have cause to worry. Then put it back together, but with the last clamp take some screen from the hardware store, I’d prefer a larger screen not a mesh, and fit it over the tailpipe end. The kill the rodents. I had three Winters of Squirrel trouble due to a contractor failing to close a corner of an eave. They got in to keep warm and I had a heck of a time getting rid of them. Good luck! Rocketman