brunnhilde's pet doors

While preparing brunnhilde for some paint refresh, I discovered where the cabin air exit ports are. They are located behind the end caps of the rear bumper fascia. I only paid casual attention to them and didn't think much about them except but to note the rubber flaps that acts as one way trap.
Of all the vehicles I have owned, or encountered VW Vanagon has the best flow through ventilation. One of the reason is very generous air exit ports strategically placed behind the rear side windows. The vacuum created by the vehicle at speed sucks the stale cabin air out very effectively - if you open the a number of the front vents.

One of my James Cook Freunde I shared the progress of my project with, pointed out that he think these two air exit ports may be the entry points of mice he had found in many occasions in his NAFTA James Cook. In our email exchange, I affectionately call these ports Brunnhilde's pet doors.

the location of the pet doors - the cabin air exhaust ports

I measured the size of the grate openings behind the rubber flaps, and they are about 0.5" x 0.75". We both agree that small mice can squeeze through them. I have heard that mice can squeeze their body through very narrow opening by flattening their torso.

the size of the grate openings behind the rubber flaps - about 0.5 x 0.75 inch

I decide to add a finer grill or screen behind the port. I looked for what I have a home and my idea was to find something smooth that does not snag onto lints. I saved some plastic fruit baskets and it seems like good candidate to repurpose them. Upon checking the dimensions of the openings I decided they are not small enough.

these material has opening that are too large

There is a good reason I am a pack rat. I saved this blower fan assembly from a swamp cooler I found on the sidewalk because it has a nice blower and motor. The metal screen on it turned out to be perfect for the project. Seeing there is very little sign of collected lints initial concern with a metal screen (we Yankees call them chicken wires) like this eased.

I didn't want to turn the project into a production. I aimed for a simple idea that is effective, and simple to complete. I want to put the screen onto the inside of the port assembly. Seeing there are 4 slots I cut the screen with 4 rectangle tabs. The tabs are bend 90-degree and inserted into the slots to function as anchors. How elegant!

note the screen is fitted to the inside of the air exhaust port assembly

Cutting the screen to shape requires some care and attention. With the aid of a Sharpie to mark some of the cut points, and a lot of careful counting of the wires to be cut I managed to created two screen assemblies shaped nicely to the outline of the ports.

 a good offset tin snips making it really easy

I use a bit of auto body filler to cement the tabs in the slot. I chose to use body filler instead of epoxy as I want to be able to replace the screen in a later day if needed. I can pick out the body filler much easier than epoxy.

the screens are secured with Bondo (body filler) and ready to be turned to the vehicle

So how do the tiny mice climb up to the bumper and gain entry through these pet doors. Animals are more resourceful than we often realize. If one use a car cover for storage it is no doubt they can easily.