By Brian Manley
Possum gets angry after he's disturbed from his cozy place under the hood. Photo courtesy of Tom Roberts, Autonerdz.com. |
We all have 'em; stories about critters that have crawled into cars and wreaked havoc. Often the poor little perpetrator just wants to have a warm place to build a nest, other times the varmint makes lunch out of a vehicle's wiring harness. Either way, the damage can range from a subtle drivability issue to major engine damage requiring replacement (no kidding ... read on).
I, and many of my colleagues, have seen enough of these cases to warrant a serious look at an often humorous, but sometimes tragic, subject. For this month's Tech to Tech, I'll share examples of mouse mischief and possum pranks, recommended repair methods, how to keep the critters out of your customer's cars, and ways to protect your health when dealing with decomposing "fuzz-balls."
Case No. 1: Wire is nutritious!
Photo No. 1: The ground wire for lunch? |
I can't decide if mice have a copper deficiency or if they simply love the feeling of sharp, pokey-stuff moving through their digestive tract, but I've seen plenty of wiring harnesses that have been nibbled at and some that have been chewed completely through. Photo No. 1 shows a recent Ford Taurus that had a transmission shifting and rough-running complaint. After test
driving to confirm my customer's concern, I popped the hood for a visual inspection. It didn't take long for me to see a possible reason for the problem: an entire ground point at the left fender had been open-circuited by mice or rats, I assumed. This wire was a major ground point for the PCM, and I had no doubt that closing the connection would repair at least some of the problem.
Photo No. 2: Teeth marks in the fuel pressure regulator hose. |
But, I always wonder just how much chewing has gone on under the hood, or for that matter, inside the car. Photo No. 2 shows nice teeth marks in the remainder of the fuel pressure regulator hose. "Sure," you're saying to yourself, "The huge vacuum leak will be balanced by the increased fuel pressure." And I'll bet that's just what that devious little mouse was thinking, too. What bothered me is what else was wandering through the grey matter of my tiny brown friend.
What else was chewed, and where is it?
Photo No. 4: The neatest collection of nuts and corn by any single mouse - ever. This was in an air box - just below the air filter. Photo courtesy of Tom Roberts, Autonerdz.com. |
I decided to sell enough labor time to remove the air box, open all of the intake ducting, and gain visual access to all of the major wiring harnesses under the hood. It turns out that there was just one more wire "open." Photo No. 3 shows one wire out of a 40-wire harness that had been completely chewed through. This damage was out-of-sight, hiding underneath a major engine harness. The vehicle performed just fine after repairing the four broken wires and the regulator vacuum hose.
The customer was happy with the repair, but perplexed by the nature of the damage. I warned her that the rodents could return, which they did one week later, chewing through the exact same ground wires as before.
I now know that the mice don't crave copper; they simply prefer ORG/WHT wires. Perhaps this is a delicacy.
Photo No. 4 shows the neatest collection of nuts and corn by any single mouse - ever. This was in an air box - just below the air filter.
Case No. 2, 3 and 4: Brake "Squeak," Hesitation and Engine Damage
Photo No. 5: Talk about squeaky brakes! Photo courtesy of Pat Andersen, Anoka Auto Care. |
I asked Patrick Andersen, owner/technician of Anoka Auto Care in Anoka, Minn., to share the next three case studies of critter damage.
One of the nice things that Minnesotans do for mother earth is to feed birds. Of course, they store the birdseed in their garage and that tends to attract rodents. There are many nice, warm and cozy places in most automobiles for rodents to make their home, as many of us know, like the heater box, the intake manifold and above the gas tank. Here are some unusual places that I have seen mice set up residence:
Warning: The images that follow are graphic and guaranteed to ruin your appetite. View at your own risk!
Photo No. 6: Courtesy of Pat Andersen, Anoka Auto Care. |
Photo No. 5: This car came in with a complaint of brake noise. Look carefully under the out-board brake pad:
This next car (Photo No. 6) had a low power and hesitation complaint:
By the way, there is no code for "Mouse nest in MAF" (maybe they're saving it for OBD3).
It seems some Mazda V-6 engines left an opening in the valley leaving the timing belt area vulnerable to rodent housekeeping (Mazda TSB No. MT 07-10). Photo No. 7 shows a 1992 Mazda 929 that ended up needing an engine due to a couple of mice in the wrong place at the wrong time. Yes, that is a compressed mouse carcass above the left inner camshaft gear.
Photo No. 7: Courtesy of Pat Andersen, Anoka Auto Care. |
Mr. Anderson has had so many of these issues, that he gives the following advice to his customers: "My advise to my customers is to keep the bird food, garbage or anything else that a mouse might eat out of the garage, even if it is in a sealed container. The aroma will attract them and once they make a home in the garage they're hard to get rid of. And if you have an attached garage then they will find a way into the house. Keep a few mouse traps set in the garage and check them weekly. Keep the grass around the garage mowed short and don't let any tall grass or weeds grow within 20 feet of the garage. Rake up acorns or other popular tree-borne rodent food so they don't have a food source close to the garage."
What Do You Do If the Critter is Still "In"?
Douglas Bree, owner/technician of D & J Autos in Arlington, Texas, contributes this painful story:
"I had a customer come in with a Volvo 740 complaining of water in the right front floorboard. I found a hole chewed in the evaporator case. Purchased a new case and upon removal and disassembly was promptly bitten on the right thumb by the offending rodent (who was still very much alive and well, living inside the case). It escaped unmolested, and I underwent a VERY painful set of rabies vaccinations."
As Mr. Bree states, we need to be wary of such situations and protect ourselves as best we can. Perhaps leather gloves are best when blindly ferreting out a furry friend from a dark heater box. I've also heard of a scare involving the dust from a dried-up critter carcass, and it is recommended that you wet down the nest and body before stirring up any airborne contaminants, lest you inhale any disease-ridden rodent spores. Use a dust mask or a respirator if you feel that this is a possibility. You can even thoroughly hose down the nest area with a disinfecting solution. Clorox bleach and water or Lysol in a spray bottle will help sanitize the area.
A Final Story ... Just for Fun
Photo courtesy of Doug Brennan, service advisor, Microl Corp. |
Sean Guerrasio, shop foreman at Morande Kia-Suzuki-Mazda in Naples, Fla., writes to the International Automotive Technician's Network (iATN):
My father replaced the motor in his '67 GTO. After it sat for a little while, he found something had chewed a hole in the glove box. He never did find the rodent. He finishes the motor, starts it up, and ... hmmm ... sounds odd. It sounded funny for a second, then there was a big POP! I was already looking at the tailpipe when I saw the chipmunk shoot out of it. He hit the ground, rolled, and ran away. I will never forget it and I doubt that the chipmunk will ever forgot it either. I wonder how that would show up on an O2 sensor graph. Hmmm...
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Brian Manley is a vocational automotive instructor for the Cherry Creek school district in Aurora, Colo. He is an ASE master certified automobile technician and a former member of the National Automotive Technicians Education Foundation (NATEF) board of trustees. He can be reached at manley_brian@hotmail.com.
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