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How to rid your car of rodents

Last month a new customer brought in his 2012 Subaru Forester X. He said every time he fills his wiper fluid, it leaks out almost immediately. He added that it leaks even faster when he engages the washer sprayers.

We lifted the car and removed the lower-left front-fender liner to gain access to the washer reservoir. That’s when we discovered that three of the hoses were damaged – but not by normal wear and tear. Rodents had chewed them.

Two years ago I wrote an article on how rodents will eat just about anything on cars. Since then we have found engine valleys completely filled with acorns, ignition wires eaten, wire harnesses eaten, under-hood insulation eaten, cooling hoses eaten and even a small mouse city – with nests – inside of a dash (perhaps using the blower motor fan as a treadmill). This epidemic seems to be getting worse.


Besides the fact that rodents seek a warm, dark place to sleep and nest, it was unclear to me why more and more of them use car parts like their own personal food court. The rodents especially enjoy the plastic wire insulation and rubber hoses.

I did a little research and discovered that some car manufacturers use fish oil to produce their rubber hoses and soy to make the wire harness insulation. I guess if I had to spend the night under a bridge and the bush next to me smelled like a hamburger, I would go for it.

The repair to the 2012 Subaru was small, but most of the time rodent damage can be costly. When the rodents eat through wire harnesses, they can short the wires and damage expensive sensors and control modules. When they fill engine valleys with acorns, the intake manifold must be removed and the entire engine cleaned.

So if you see signs of rodent activity in your garage or driveway, it might be time to take action. Setting traps and blocking off small holes into the garage is a great first step. Rodents can also be deterred by their sense of smell; there are several repellent sprays available for purchase online. Some of these sprays feature essential oils known to repel rodents. I would suggest reading the ingredients and staying as natural and green as possible.

If the rodents have already gained access and caused damage, we have found the ideal deterrent. Honda makes a rat tape infused with chili pepper oils. One bite of the tape and the rat’s mouth is figuratively on fire.

We had a customer from the Palo Alto foothills who replaced his wife’s ignition wire set five times before coming to us. The customer had built a cage around the ignition wires, but the rodents still got in. We removed the eaten ignition wire set and wrapped the new wires with rat tape. Two years later, the rodents haven’t returned.

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