How To Keep Rodents Out Of Your Engine Compartment

Wyatt was the first to discover the chipmunks hiding out in the engine compartment of our truck. At first I found his antics funny, but they weren’t enough to keep the rodents from coming back.

Wyatt Keeps Chipmunks out of Engine
Wyatt on Chipmunk Patrol

Then I discovered the pests were actually nesting in the insulation, tearing up the hood liner.

How To Install Mouseblocker
Rodent Damage to Engine Hood Liner

Knowing that mice and other rodents can cause serious damage by chewing through hoses and wiring, the fun and games were over! After evicting a half dozen of the little vermin, I was determined to find a solution for keeping mice and rodents away from our engine. Coincidentally, a neighbor stopped while I was tracking down the last little rascal. She told me about an expensive repair bill she recently had for damaged automotive wiring, and showed me the MouseBlocker she had installed under her hood.

[box type=”note” icon=”” style=”rounded” border=”full”]NOTE: The clips in the photo above are holding peppermint mouse deterrent packets, which clearly did not work against our family of chipmunks![/box]

Install Mouseblocker to Prevent Engine Damage by Rodents

The MouseBlocker is a 12v ultrasonic mouse deterrent. Designed to keep mice away from your engine or any area you wish to protect, the MouseBlocker emits a high frequency audible tone in 15 second intervals. The small device runs off your vehicle’s battery and draws only as much power as an LED clock. The manufacturer assures that this allows the MouseBlocker to run for months at a time without any excessive drain on the battery.

How To Install Mouseblocker
MouseBlocker Ultrasonic Automotive Mice Deterrent

The MouseBlocker is easy to install and can be used to protect your car, truck, or RV from rodent infestation. Install it virtually anywhere with a 12v power supply to keep mice away from automobiles, cargo trailers, or your RV’s storage compartments.

How to Connect MouseBlocker

The MouseBlocker unit can be mounted in your engine compartment with the included self-tapping screws or zip-tie fasteners. The device should be placed in an unobstructed manner that allows for consistent broadcast of the acoustic noise that will not be absorbed by insulating mats.

The MouseBlocker wires connect directly to your battery with the included terminal wire connectors. My only complaint about the MouseBlocker is that the wires attached to the device are too short for use in a large truck like our Dodge Ram 2500. While they may work fine in a smaller vehicle, I just had to extend the length of the wires using extra 14g automotive wiring with a couple butt connectors.

How To Install Mouseblocker

For Installation, you will need:

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MouseBlocker Wiring:

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  • Black Wire = Positive (+) Battery Terminal
  • Brown Wire = Negative (-) Battery Terminal
  • Grey Wire = Positive Ignition Source.*


*Optional: No connection = continuous operation. Refer to your vehicle’s service manual for finding a switched ignition source.

Steps to Install MouseBlocker:

1. Determine mounting location for device.

How To Install Mouseblocker

2. If necessary, measure and attach required length of additional wiring.

How To Install Mouseblocker

3. Attach terminal connectors to wires.

How To Install Mouseblocker

4. Attach wires to battery terminals.

How To Install Mouseblocker

5. Mount MouseBlocker and secure wires.

How To Install Mouseblocker

6. (Optional) Connect switched ignition source.

If not connecting the grey wire, your MouseBlocker will simply remain on when the vehicle is in use.

[box type=”alert” style=”rounded” border=”full”]All wires should be routed and secured in such a way that they do not interfere with moving parts or contact hot surfaces.[/box]

MouseBlocker Two PackHave multiple vehicles, or want to protect your RV storage bays too? Save on the MouseBlocker 2 Pack!

Concerned about the drain on your 12v electrical system? Don’t want to deal with the wiring? Consider these battery powered rat and mouse Repellers!

Since I installed the MouseBlocker, Wyatt has yet to corner any more mice, chipmunks or squirrels under the truck—only where they belong…


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6 thoughts on “How To Keep Rodents Out Of Your Engine Compartment”

  1. Jim, great to see a blog on this product. Can Wyatt hear this device? Does it bother him? I need to do something about some critters nesting in my car engine, but I don’t want to bother my dog.

    • Thanks for asking Doug. Wyatt has never been bothered by the mouseblocker sound…only by the chipmunks that moved in before we got it! And we haven’t had any since…

  2. Hi Jim,

    I’m new to your blog and currently browsing through. On the mouse deal…you can also use a c.o. detector with a low battery and accomplish the same thing. Enjoying everything so far.


  3. Nice write up about a useful gadget. I had rodents of some sort build a nest in the engine compartment of a pickup while on a campground, for just one night. They can do a lot of damage in very short order!

    Are you going to use them in the RV? If so, where do you plan to locate them? And how many would you install in your RV?

    • Great question! We haven’t seen a need to install Mouseblockers in the trailer yet. If I did, I would likely install four units, located over the axles or other entry points and in the locations where rodents would be likely yo do the most damage.


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