MouseProofing the Prius

[ebsmythe]

Since finding evidence of mice in my glove compartment and also in the utility box under the hatch floor, I resolved to do my best to close all entrances, not only those to the air intake system, but also to the hatch area. There have been good posts on this site for most of the work and I used all this info to take things apart. Nowhere did I find a complete run down of everything in one place so I took some pictures as I worked this morning to record the process. The entire job pictured here took about 3 hours because it was my first time. My wife's Prius is next and I expect it will take me about 2 1/2 hours now that I am more familiar with taking things apart.

I started with the hatch area where Patrick Wong had shown us that there are two openings which allow air to leave the car fast when you close the hatch.
There are rubber flappers in the plastic frames of each hole which would be nothing for a mouse nose-push.

To access these holes the floor and side trim panels need to be moved.
Here is what my hatch area looked like when I peeled the side panels back.
It looks awful doesn't it?
What you will see is one opening behind the 12V battery on the passenger side which looks like this To obtain access to this opening it is necessary to remove the section of black plastic vent next to the battery. It is attached by two bolts and is not hard to remove. Once the black frame can be freely accessed, a screen was measured and bent to suit. The black flapper valves are in a plastic frame as you can see and are not straight but rather curved in a way which makes it more difficult to screen. I used 1/4" galvanized mesh and cut the shapes with tin snips. Here is the screen for the passenger side near the battery before it was installed Mine looked like this after it was installed with self tapping metal screws. When the vent piece was bolted back in position the screen can be seen peeking out above and behind the vent like this

On the driver's side there is no vent and the frame is larger and oriented horizontally like this The frame is also irregular but a box-like frame was measured like this and installed like this


Once the hatch area was put back together I moved to the front cowl area to tackle the many holes under the top grille and behind the water collection trough. I used an excellent post on "Prius heat efficiency mods" to help me (with lots of photos) to take the top cowl screen off, then remove the wiper assembly. After that was done the holes were all in the open and looked like this on the passenger's side and this on the driver's side. I used Ct. Ken V (thanks Ken) idea of making a cardboard template and fitting it in place before cutting the screens. They looked like this on the passenger's side (note the small screen on the drain hole) and like this on the driver's side. That colored mexican blanket above was covering the windshield to stop reflection from above

That was it once all was re-assembed.

One last thought about possible mice entrance points. This photo you will recognize as the passenger side quarter panel area. That black area is inside the quarter panel which is wide open to mice. It is the same on the opposite side of the car. Once they go down in there, is there a way for them to enter the behind dash area or the cabin? (Patrick Wong what say you?) I hope not or all this screening will have been a waste of time.

[Bill Merchant]

Great write-up and post, ebsmythe! Thank you.

I can't speak for Patrick, but I think you have covered all the access ports, I don't thing there's a way from the front quarter-panel into the front vent system.

[ebsmythe]

One more screen that I had intended to install (but forgot) is to prevent mice from entering the engine air filter area. I saw a post with a picture of a screen at the air box end of the intake tube. I looked to see if the other end of the intake tube (the intake end) was accessible but I could not see much down behind the headlight and ended up not doing this screen.

Has anyone screened this mouse entrance at the intake end? How did you access this spot?

[freshmtt]

HOLY CRAP!!, You did an amazing job and such determination to keep those pesky buggers out of your Prius Great job!!

[Ct. Ken V]

Hi again, Barry,

The intake end for the engine air filter box is right out in the open right before your eyes (though not really that obvious). It's a reverse "L" shape about 6 inches to the left (passenger side) of the engine air filter box, between the junction block of the high pressure side of the air conditioner line (the metal block with the little glass inspection port) & the lens of the passenger side headlight, just forward of the windshield washer reservoir.

Also as you look at the black plastic panel that crosses the entire car between the headlights & is also (front to rear) between the grill & the HSD inverter, it's only about 1 1/2 inches from the pointed end of that panel on the passenger side. You need to remove the 6 plastic fasteners that hold that panel in place (the front edge of it slips into a groove in the top part of the grill piece) because underneath is one screw that holds the somewhat wobbley intake end piece in place.

When you fasten your screen mat'l onto that intake end piece, use star type lockwashers & SHORT screws (because long screws with that wobbley piece may eventually rub against & pierce the adjacent air condition'g high pressure line).

Thanks for your excellent post & accompany'g pictures of your job. I still have to do my rear vents & I must admit that I didn't even notice on mine those 2 little drain slots in the front that you also screened off. Mine were (& still are) covered up with some kind of debris, but remember that I only removed the 2-piece black plastic tray & the windshield wiper transmission. If I had gone one step further & removed the next panel, I might have noticed those 2 extra drain slots. Thanks again for your excellent photo documentation.

Ken (in Bolton,Ct)

[cyberprius]

The mice will win. You cannot resist the mice

[traugu]

EXCELLENT job!!! Now, if I could only come up with the confidence to undertake this adventure......

[Patrick Wong]

Originally Posted by ebsmythe

... That black area is inside the quarter panel which is wide open to mice. It is the same on the opposite side of the car. Once they go down in there, is there a way for them to enter the behind dash area or the cabin? (Patrick Wong what say you?) I hope not or all this screening will have been a waste of time.

Congratulations on doing a comprehensive job, and many thanks for documenting each step with your great photos!!

I'm not sure about the black area shown in your last photo. Is it possible to install more wire screening to block that hole?

Now that you have wire screening over the two rectangular cowl drain holes, they will be very easy to clog up if small leaves accumulate in that area. In that case you should hear water sloshing around as you drive.

[dwreed3rd]

Grrrrreeeeaaaat Job! Very thorough! I have added it to my A-List of Mods.
Thanks for sharing your hard work.

[pewd]

Thanks for taking the time to document and write this up.

Have you considered simply adding a Cat to the front passenger seat?