Keeping Mice from building nests on engines

Recently, I had mice to build a nest on the in-take manifold near the V6 engine’s injector plugs. They took the opportunity to chew the wiring harness free from two injector plugs. The Dodge Dealership had to look long and hard to find parts to repair the damages since they have discontinued this year’s specifications. I keep this truck at a vacation home, and it is driven about every two weeks. Any suggestions for keeping mice out of engine compartments. I have been advised about moth balls, dry sheets, etc. Is there a pesticide rub that can be applied to the wiring harness that causes mice to avoid chewing the wires?


Beware of pesticides. The added heat from running the engine could evaporate the pesticide and then you might breathe it. Also, the mice could fall or crawl into an inaccessible spot and smell awful for a while. Maybe you could put traps around the truck (on the ground).

Could install a blacksnake in the might try capsacian
(red pepper) probably wont stop them though,rodents need to chew on things to keep thier teeth from becoming to long,its really hard to keep mice and rats out of under used vehicles.The more open it is around your parking area the fewer rodents you will have, mice love cover and keep garbage in something the little critters cant get in-Kevin

Is the vehicle in a garage or outside?

I’ve read that cayanne pepper (sp?) repels them, but I cannot testify to that.

Perhaps a call to your state’s Department of Agriculture office will yield a definitive answer. They have experts in rhodent control and their services are free.

The truck is kept outside on a driveway.

D-con won’t repel them, but has the effect of making then stop chewing wires, or anything else for that matter. The unfortunate side effect is that they may hang around a while and stink as they decompose.

If you have comprehensive insurance coverage, the mouse damage should be covered. Ask a (former) local packrat how I know.

I live in a Third World village in the mountains of Mexico. Several years ago, when we came back from a visit to the States, I found a nest of mice in my underwear. We also every week or two found a scorpion in the house, and their stings are nasty.

I went to Aurrera, subsidiary of Wal-mart, and bought some ultrasonic pest repellers. We go months at a time with no scorpions, and only twice have I seen a mouse. The first was dead under a block, obviously crawled in there to get away from the sounds.

The second was in a corner which was not covered by ultrasonics very well, so I bought another one. No mice since then.

Lowe’s and Home Depot sell them, though they are probably not as powerful as what I buy here.

Clearly, one would have to supply 115 volts to it, and take it out when you drive. But, I have first hand knowledge those things keep the pests away. Sadly, they do not keep spiders away, and I do not know about snakes.

The man who watches our house when we are not here has found dead lizards near the ultrasonic machines.

Tobasco sauce, applied to the wires with a brush or spray will prevent wire chewing…There are commercial “Mace” type personal defense spray cans that would do the same thing… Moth-balls will prevent nesting. Ultrasonic gizmo’s have been proven to do nothing…

Only problem with moth balls is the smell, and if you get them near a heat source and they get hot…

Ultrasonic gizmo’s have been proven to do nothing…


Proven by whom?

Have you tried them, or is this something you read? My guess is, the latter.

I have consistently said I am not sure how well the lower powered ones in the US will work. But, I have personally tried them here, for some years now, and they do work.

I am not going to dig out the paperwork right now, to look up the manufacturer. They are built like a little speaker, 3 or 4 inches on a side, and the specs said they are 1.5 watts. If you hit the test button, it drops the frequency into the audible range, and it is loud, like a squeal.

One day several years ago, our builder was in the house doing something, and I was sitting by the door reading. A lizard went running across the floor very fast and a few feet in front of the ultrasonic, he froze. I said, “Hey, Virgilio, look at this.”

He came over and said, “That is a poisonous one.”

I walked over, took my shoe off, and converted him to room temperature. He never moved a muscle, which is very unlizard like.

Virgilio said, “One day when you were gone, I found a dead one in that same place.”

Our scorpion count went from a couple a month to none for months at a time, but my wife finds them in the yard all the time. And, when we do find one, it is hidden near the old door under the boxes of storage my wife puts there. (A door hundreds of years old my wife salvaged from her ancient family home, and we had it built into the house. It has those big nail heads like you see on Mexican cathedrals, but is not in great shape, so anything can walk in under it.)

When we started living here, we had ‘mouse tracks’ all over the house, and they built a nest in my underwear drawer. Since we put in the ultrasonics, we have seen two mice in the last several years, and one of them was dead. It had apparently sought refuge under a block, because when I moved the block there it was.

Now that I think of it, in our trailer in McAllen, we had a lot of mice coming in. We put in the light ultrasonics from HD, and it seemed to help some, it’s hard to be sure, because I also put hardware cloth around all the pipe entries. So, I can’t be sure, but here in Mexico I am sure, and so would you be if you lived here.

I live in Mexico for 9 months a year…Scorpions come and go…So do lizards…They come with the territory…Remember the ultrasonic deer whistles everyone was paying $10-$15 for?? They didn’t do squat either…I’ve never seen an ultrasonic pest repellent sold in Mexico…They sell pesticides down here that actually work…You want some Chlordane? No Problem! Diazinon? 10 or 25 percent?

If you haven’t seen ultrasonics sold in Mexico, then I must assume you are legally blind, yes? They sell them in almost all Wal-marts and Aurreras and I have bought them both places. That is the second time you have slapped my face, Caddyman, and it is getting tiresome.

And, let me point out that essentially you are admitting, as the pooh-poohers of synthetic oil admit they have never tried it, that you have never tried the ultrasonics. I have. You know much more than I do about cars; I obviously know much more about these pests and ultrasonics than you do. Yet, with no personal knowledge of the devices, you continue to slap my face.

I am well aware that those pests come and go in Mexico, sort of, based on rainy vs. dry season, etc., and implying I am too ignorant to know that scorpions and lizards come in the house more at certain times of the year is also insulting. But they do not come and go in my house since I installed the ultrasonics.

And, when I tell you I have seen the ultrasonic freeze a lizard on the spot, and you pooh-pooh this, let me make it clear you are calling me a liar.

A snake is a bad idea.