As I'm sure is common to many of us, we park our trucks outside. Some parking spots are closer to nature than others, and if there is an occasional or prolonged period where the truck isn't driven, the truck gains inhabitants that don't sign leases. This was the case very recently after two weeks next to a grass field that just also so happened to have been cut for harvest at the same time. Earlier in the year, shortly after I'd bought the truck, I put a drop-in replacement engine air filter as part of normal maintenance and just going through the truck as it was new to me. Found a huge mouse house stuffed in the lower portion of the air box that was actually dislodging the air filter from its original install location. Thankfully nothing had gotten by, but wow. Gloves on, filter and mouse stuff in the trash, and a cleaning up of the air filter box.

Fast forward to a week ago and I had a K&N drop-in filter arrive in the mail. [After reading about cold air intakes on numerous threads and researching available options, I opted to simply optimize my stock setup as there are other airflow and aesthetic fish to fry in this regard that aftermarket companies, to me, aren't addressing] Good thing I did because I had another mouse house well under construction, fueled in part by fibers from my replacement under-hood sound insulation (accessed via the top of the radiator shroud). So out goes that air filter and mouse junk, another cleaning, and the installment of the K&N unit. This time, this work is accompanied by further research into general (field) mouse size informing wire mesh size to somehow install somewhere to stop the madness.

Both times leading up to the discoveries, the truck felt a little wheezy. Both times after filter replacement, there was noticeable improvement, and the K&N has actually delivered on whatever promises of improvement by...improving slightly. These are heavy trucks with a legacy small block engine, for truck duty (for years), with incremental improvements--no hidden rocket ships to discover, but the added pep "under the curve," plus a touch extra intake bellowing, has been appreciated, as has the fact that it's a long-lasting filter (I've bought these before for other cars).

Anyway, this is for the 5.2L and 5.9L V8 and 3.9L V6 Magnum engines as all use the same airbox and intake tract pieces. I did this for less than $1 and it is Version 1. Hopefully it gives anyone else with this (potential) problem something to work with. As always, do this at your own risk/I accept no responsibility. I've had this setup running for about a week and haven't felt any change in performance, so ostensibly it is discouraging mice from squatting. I've also been driving it nearly every day, which is probably the primary method of keeping them out.

On to photos!

Intake tract as it connects to both inner passenger-side fender walls:



The dashed green line is where the intake tube stops against the fender wall, with the channel to the left the part that "snaps" into place. Well, that green line section, part of the molding process, is its own internal channel, which is perfect for placing some mesh to self-secure/locate.



Obviously this inner channel's dimensions are larger than the opening, which presents a sort of ship-in-a-bottle scenario. I also seem to remember there was a larger mesh here already, but I could be mixing that up with something else?

 

Mesh Time. For about $12, or $23 if you want the accidentally-paint-matching vinyl-coated version, you yourself can get a huge five foot roll of 1/2" steel/wire mesh. So much left over for garden and pet activities! :lol:

The absolute size of this inner channel is 7 3/4" wide x 3 3/4" tall. The channel is shaped like a track oval, with both left and right radii being just under 2".

I "over-cut" by a 1/4" or so to give myself extra material to work with:



The extra material was cut down, still slightly oversized, but with "prongs" available to dig into and anchor in the channel.



Radii are cut and everything is ready to be semi-awkwardly (yet carefully!) partially-folded and slipped into the intake tube (from where it secures to the fender wall):



These were nearly all the tools used. Old heavy duty scissors/tin snips found in my dad's toolbox, plus some of my pliers:

 

The other two tools are a bench vice for gently (gently!) holding the intake tube steady as well as a long narrow stick or shaft of some sort (end of a broomstick, 1" wide PVC pipe section, cardboard poster container, etc). My chosen implement was a fireplace poker with a 90° bend at the end, which ended up being great for pushing more mesh around at once plus working the corners/prongs of the cut mesh into the inner channel.

Let it be known that this is a fidgety and imperfect process. This was me partway through.



This is the final product, which I would argue doesn't look at pretty as the in-progress mesh, but nevertheless, all the "prongs" and mesh in general are extended to the furthest points in that inner channel, and I was able to add some (thick/gel-type) super glue to a number of points to provide additional security. Even before then, giving a decent push on the mesh resulted in that mesh simply flexing but not moving position.

The only potential issue this solution has is that there is a 2"-ish section where mice could set up a fruit stand, and that stuff could find its way into the tube. So I'll have to check here soon to see how that goes and report back. Hope this helps. Thanks for reading along!

 

Nice Fix.

 

It may not stop them. A small mouse can get its head through the squares. If they can get their head through, they can get through. The skull is the only really solid bone in their body. The rest is mostly cartilage..

 

I swear mice can make themselves two-dimensional, and slip thru the tiniest crack......

 

I realize there is a semi-futility here, but I/we do our best. If there was a vertical access point for the air, tall enough and perhaps slippery enough that mice couldn't get in (or get in nearly as easily), that would be better. Better still would simply be having the air filter unit be the gatekeeper to the whole intake operation. I know cold air (or "cold enough air" as I say sometimes) intakes provide that solution, but the issue for me there, aside from the yuuuuuge intake box/conference center on the passenger side of the engine bay, is that the companies will just put a simple mini hat right above the throttle body, which does not make for ideal airflow IMO. Maybe the super low hat 'ceiling' is fine and I still don't know anything, but that's the next area I'll be tackling pretty soon now.

 

A wire mesh over the wire grate should do the trick and not reduce air flow much.

 

I had considered the mesh as a solution, but wondered about airflow restriction. Just checked the truck after over a day of sitting. So far so good--no trace of any mice or debris. Still parking near the field as before.

 

The mice are going to wait until you think you have won, then they will move back in.