Before my engine build my engine bay had plenty of mice camping out. After I installed the rebuilt engine I wanted to keep the truck mouse-free. Here's what worked for me.

When I pulled the air intake assembly I found the air filter box a mouse condo. I added the aluminum screen shown below, and that has kept them out of the air box.




I did a lot of online searching and learned mouse hate the smell of peppermint. I tried the suggestion to add a couple dozen drops of peppermint oil to water and spray the engine bay. But that didn't work and just made a mess. Since the mice like the top of the valve cover, I stapled small pieces of thick felt to a heater hose and vacuum line above the valve cover. About once a month, I put a dozen drops of peppermint oil at the bottom of each felt and that has worked for over a year now.





I was excited that this kept the engine bay free of mice for over a year. Then, after I was away for a month, I returned to find the engine bay mouse free but the mice had set up camp in the blower cage. Through searches in this forum, I learned where the fresh air intake is located under the cowl and how mice use that path to enter the blower cage. I saw someone's elaborate and difficult solution to cap the air intake under the cowl with screen. But I didn't want to go to that effort. Again, once a month I add about a dozen drops of peppermint oil to a long piece of the same thick felt and I feed that felt into the passenger side hinge opening in the engine bay. That gets the peppermint close to the air intake and has kept mice out of the blower cage for almost a year now. Maybe this solution will help someone else with a mouse problem.

 

I've never had mice in my 94 and only had mice in my 87 one time and that might have been from leaving a window down. My 95 and 90 Corollas both had terrible mice infestations in their blowers, constantly. My Rav4 never gets them either.

 

Got a Camry once that had maggots crawling out of the vents. A rat had lost a fight with the blower motor. Smell was horrendous, and being a hot summer didn't help.

 

Well all this mice talk reminds me to get my truck out today I wish I had room in the garage but then I would have to kick the lady out of her side. Although the area I’m in doesn’t seem to have too many mice all it takes is one of these little cute bastards to ruin your day

 

Thanks for posting this. I thought about the screens for the cowl because the only rust I've had on my truck was from Mouse urine/nests eating holes in the cowl. Weird that they never got into my A/C. Just the inside corners or the cowl.

 

I never had any mice inside the cab, only in the blower motor and engine bay. The first post in thread Mice in blower /Cowl area has some good pictures showing the location of the fresh air intake under the cowl. The pictures show how close the air intake is to the passenger side hood hinge. Feeding my peppermint oil-soaked felt into the hood hinge opening in the engine bay definitely gets the peppermint close to the air intake and has been working for me. Some have said, they always leave the heater's air control on Recirculate when they leave the truck, which closes the flap above the blower. Others have said, that just lets the mice nest on top of the flap and soak the flap's foam with poop and urine. Peppermint near the air intake has been the solution for me.

 

Its not that hard to keep them out of a pickup, at least not mine. And I have a mouse population thats second to none. My cat is the best mouser ever but he can't keep up with them. My shop is mouse proof because it's got stone walls but everywhere else I have to have traps out non stop. So if they can't get into my vehicles out here they can't get into them anywhere. You probably just have a hole in your firewall somewhere that needs plugging

 

I think your 89 has the same body as my 94 and I've never had a single mouse in it the 12 years or so I've had it. Are you sure that air intake is where they are getting in? Maybe I have had it on recirculate for 12 years and maybe they can't get nest on top of the flap. It is on recirculate now.

 

The hole I have is from their nest and urine. No rust anywhere else on this desert truck. The 80's pickups have EASY access for rodents to get into the cowl. One huge (for a rat) opening on each side that you can see if you ever have the fenders off. This particular truck had it happen because it sat in a field before I bought it. I don't really have a rodent problem at my house but I appreciate the peppermint technique you posted because I have a boat and a travel trailer that sit at times. Good to know a method that works if I need to use it. Thanks again.

 

I can't be certain. But there are many posts with mouse nests in the blower cage and that air intake under the cowl goes directly to the blower. I read somewhere that the cowl drains behind the fender so that's a path to the air intake. That single piece of peppermint-oiled felt that I feed in the hinge opening is the only thing I have done since I found the nest in the blower cage. And there haven't been any nests in the blower since, so that appears to be their entry point. Count yourself lucky that you don't have the same problem. My truck is parked in a pole barn that is surrounded by acres of pasture offering an endless supply of mice.

 

So here's a six month follow up. The once a month peppermint still keeps the engine bay mouse free. But the mice have decided they can tolerate the peppermint near the fresh air intake to get into the blower cage. That has happened several times. Leaving the blower flap on recirculate works. But if I forget to do that the mice head right for the blower cage. I decided to create a physical barrier to entry. Here's the air intake at the top of the blower housing after removal.



I added aluminum screen with JB Weld just like I did for the engine air intake box. Then I cut and glued a new foam gasket.




Below are the blower motor and the two parts of the blower assembly. Removing the blower assembly is not too bad if you loosen the bolts holding the A/C cooling unit. The mice could still decide to nest on top of the screen. But they haven't nested on top of the blower flap probably because that puts them too close to the peppermint. I'll post again if this solution fails.

 

I did something similar to my 95. Not for rodents, but leaves and debris. My fan motor was plugged, as was the evap. So good dual use you built there.

 

Good to know. But if you are getting leaves and debris in the fresh air intake, doesn't that mean the snap in plastic grills under the cowl are compromised?