Subaru 2001-2002 SF GT Forester Pest Proofing

2001/2002 SF Forester GT pest proofing.

Over the past few months we have seen a number of incidents with our cars being targeted by rodents, the Forester getting most attention. We live on an acreage, and have orchards with tropical fruit and Macadamias growing. Most of the year there is something edible in the garden, and unfortunately that attracts pests. Add higher than average rainfall and the numbers of rodents explode.

The main problem, and major frustration, when trying to resolve this problem is that cars have a number of design flaws, creating easy pest entry points, and manufacturers don't give a rats..

The main flaws:

#1: The external air flap in between the bulkhead and firewall, hidden in the wiper chamber – the most common entry point. As the chassis is full of drain/access holes, this chamber is easily accessed by rodents, and as the vent has a horizontal flap with an enclosure on our SF Forester, they seem to enjoy setting up their leaf (etc) nests on that spot.

#2: The pressure release valve (sometimes two) hidden under the rear bumper. That is to release air via externally opening flaps when you shut the doors. As it is a vertical normally closed valve, you don’t see the same nesting issues, and it is more difficult to access due to the location.

I’m not sure of the exact location of ours, as its not in my Subaru manual! ..though I believe its in the side of the body where the rear plastic bumper wraps around. I don’t know whether they are on both sides, or one. For fully securing your Subaru, pest proofing these with grilles is also a good idea.

Both weak points are frustrating, as from a manufacturing perspective there is minimal cost involved in securing those entry points with stainless or aluminium mesh.

This DIY covers #1, which is the main point of entry in my experience. It is specific to 01/02 GT SF Foresters, though is probably applicable to other SF models – check with the pictured template first.

The cost for this project is quite cheap, at ~$20AUD, unless you have some of the gear already.

You will require:

• ~500mm of 20mmx1.6mm Aluminium plate @$3.69 for 900mm
• Around a 250mm x 300mm piece of aluminium insect screen mesh. @$11.50 per metre
• Aluminium rivets – most will do. I used 4.8 x 6.4mm blind rivets @$4.20/25
• A drill for the rivet holes, bench preferable - ~4.8mm
• Pop riveting tool
• Metal sheers for mesh.
• Hacksaw – otherwise use metal sheers.
• A vice is useful – otherwise some multigrips
• A punch is handy for getting the holes accurate, and piercing the aluminium mesh for rivets.
• Plastic pry tools for getting the cover off without damaging it.
• A decent torch and some screwdrivers.

Rodent protection ideas:

If you do a short trawl of the internet you will find plenty of nightmare cases, while suggestions for fixes that are often lacking.

Here are a few of the common suggestions, starting with the most obvious:

1. Keep all windows closed.

- pretty obvious, and most people do this regardless of rodents.

2. Use peppermint spray around the engine compartment.

- would work for a while, until the pesky rodents get used to it.

3. Never leave your car with air set to outside flow, always on recirculate.(note the air flap comments..)

- Will not stop them getting in! the air flap can be pushed open with force.

4. Never leave any food in your car, rodents will smell it and try to get in.

- great, no food inside, they get in anyway.

5. Leave the bonnet/hood up as often as possible. It will supposedly make that spot seem less safe.

- Not exactly feasible for most people, especially in windy areas, and it didn’t stop a rodent from getting onto the engine anyway!

6. Use an ultrasonic rodent repellent.

- Reviews of these look patchy, and again.. they get used to it.

7. Get a Cat, or keep a pet python in your car.

- may not be for everybody, relying on a cat for pest protection is not going to end well, and you probably don’t want to have to wrestle a python off your steering wheel.

Essentially, most suggestions are applicable to your home, not your car, even when you park in a garage/carport.

The usual process for controlling rodents and other pests is to block off the access points, then lay traps if there are any still around. That’s all fine for a house, but a car is like swiss cheese, the chassis is full of drain and access holes. The other problem is the volume of wiring and rubber hoses, as rodents such as rats need to chew nonstop to wear down their teeth, a car is the perfect place to live, there is plenty to gnaw on.

Rodents are also thought to be attracted to electro-magnetic fields, leading some people to suggest disconnecting your battery if your car is not often used. The insulation on electrical cables used by some auto manufacturers also uses peanut oil, vegetable oils, or even Soy as a base in the extrusion process, it may also be in some rubber/plastic components.

On our cars it seems that they either love getting a hit of Bars Bugs windscreen cleaner, or just can’t get enough of the 6mm windscreen washer pipe. On a number of occasions they have munched right through those hoses, they also enjoy nibbling on the yellow caps on the washer bottle and expansion tank.

The Subaru hose munching was simple to fix, it now has braided mesh wire wrapped around the new washer hose which seems to be surviving well - as per picture #1 and #2.

Air intake – fan housing:

The air intake flap in our 2002 GT Forester (2.0 Turbo SF) is in the wiper chamber on the passenger side, to the side of one of the inspection panels – it is only just visible.

If you turn on your blower, and select the outside air switch, that inlet flap drops down to allow air to be pulled from the wiper chamber. If you hear a tackitytack sound from under the dash – chances are a leaf (or 100) has just been deposited in your fan housing.

When this first happened to us, we were on a drive and MrsC said ‘lets get some fresh air’, and flicked the Armageddon switch. The end result was a full nest of leaves dropping through the chamber into the fan casing, with some pushing into the cabin filter housing. On that occasion, the fan was completely jam packed full of leaves, nothing like the pics above.

Air intake – Cleaning the fan:

Dropping the fan out of the GT Forester is not difficult, it is just a plug to remove, then three screws in the casing under the passenger side of the dash, with the rear one being a bit of a pig to remove. It’s a 10-minute job. It’s the part after removal which will take the time, and make you feel like a contortionist, since you need to get under there to remove everything from all the chambers. Cleaning the fan blades is also a delicate process, a nylon brush will speed things up a bit.

Pic#1 is our manky looking fan… nowhere near as bad as last time, but enough to sound like Maracas:

Pic#2 is post cleanup:

Air intake – cabin filter:

The GT cabin filter is easy to access, though a little fiddlier to remove. The unit is next to the fan in the ‘01/’02 models, in the passenger side foot well under dash - not behind the glove box as in some Foresters.

Remove the two screws at the front and work out the pivoting base at the rear, the housing should drop down a little showing the pair of filters. There are two rectangular filters, attached to each other with a plastic track, the bottom one is attached to the housing cover with a track. To get them out you need to slide the bottom one off the top one, there isn’t enough room to drop them in one piece. They are easier to get out than to install, and you WILL need to remove them if you had rodents, they will probably stink, and I have heard of some being munched through or nested in.

After cleaning everything thoroughly, I use some Mr Sheen on a rag stuffed into the chambers to neutralize odours and it is then ready to reassemble.

Air intake - fresh air flap:

OK, if your eyes haven’t glazed over you have finally made it down to the DIY fix step..

The car needed a screen on the air flap, ideally to keep leaves and rodents out for good.

Pic#1 is the location of the Forester air intake – offset under the RHD panel in the windscreen wiper chamber. Remove the panel and you still cannot really get to the air intake.

Pic#2 shows it from an illuminated angle, this little flap chamber is rat heaven:

Step one was to design the screen clip. Obviously, it needed a net for air flow, and one that cannot be chewed through, so that ruled out 3d printing.

I considered a frame using automotive trim clips as a way of fastening, but ended up opting for a piece of aluminium plate at close enough tolerance to spring fit over the chamber. The Aluminium frame has aluminium window mesh rivetted to it, using short retention plates.

Pic#3 is my first template for the top of the chamber, it has been
fine-tuned after a number of attempts. Note that the top edge of the chamber curves outward with a distinct lip, and there is no edge on the firewall side, whatever clip is placed there needs to be three sided.

I thought I would check this design first, to see if further reinforcement was required. If required I could cut a straight piece of aluminium as a clip for the bulkhead side, with 90+ degree bends on each end to spring fit. I found that extra clip is not necessary, and would also complicate the install.

Pic#7 is the aluminium bracket, and dimensions, bent to the approximate size using the template as a guide. Initial bends were started with the strip of 20x1.6mm AL in a bench vice, after that it was not too difficult to do the rest by hand, forming to the template:

There is limited access through the two inspection holes, and no real access to screw anything in position. The screen needed to be a little flexible to squeeze through there. I found that it would only insert through the left inspection hole (not the one marked RHD..), you need to push the clip in on an angle, oriented in its final positioning, left side down first..

After a fair amount of adjusting I found that this screen base was clipping into position nicely. If the dimensions above are used, there is no need to use additional clips.

Ensure you leave a little slack in the netting when it is attached, as the frame is slightly below the full width and designed to spring fit outwards then back into place, so the mesh needs to have some free play. Also resist the temptation to fix anything across the bulkhead side, you will not be able to squeeze the frame through the inspection hole..

Once the clip was checked for a tight fit, I have cut some Aluminium window netting oversized, folding the edges a few times, and folded the section that meets the firewall 4 times for rigidity. The netting is sandwiched into the frame with alloy rivets, from the inside. I figured the rivets would also assist to keep this clip in position, as they will hit the lip if something does try to push it up.

The screen mounting plates are two 90mm pieces of alloy for the sides, and a 105mm piece for the front.

The plates are drilled then formed to the same curvature as the base clip. Note netting partially attached in pic#7.

Pic#8 shows the end pieces drilled and formed to the shape, ready to rivet:

Reinforcing the sides adds a little more spring to the clip, and keeps the aluminium netting secured at its weakest point – the firewall side.

Finally pic#10 shows the completed pest cover:

…installing in the GT (2.0S turbo for US folks).

Start by getting the left side in on an angle, you will need to push the mesh a little in the middle to avoid snagging it..

Slide it down on an angle to the left.

Then rotate the clip a little to the right.. and it will be in the right orientation to attach. Then shuffle it past the next inspection hole to the right.

I found the best way was to place this above the Air flap, then clip the difficult side in position, then work on the side you have more access to. Using a torch, all will be revealed if it doesn’t want to fit. I removed the frame from the car a couple of times, and bent one clip back a few mm to get it to fit nice and snug. Final pics are a little poor due to lighting..

Note this doesn’t stop them getting into the windscreen wiper chamber, it only blocks the cabin access, and any leaves dragged in to this zone will no longer drop through into the fan shroud.

Only time will tell how well that secures the air flap. I doubt anything will be able to get the cage off the chamber – it is very tight. The only weak point is up against the bulkhead where the wire is taut enough to not allow anything past it, though this is wrapped and reasonably rigid it would be the only possible flaw. The beauty of aluminium mesh is when it is frayed it can be like barbed wire – and I left the final edge around the bulkhead very frayed.

There really are no guarantees with rodent proofing, as their teeth are rated harder than steel, all that can be done is remove the temptations, and make it as difficult as possible. Some suggest copper, though soft, is a more annoying mesh for them to chew on, so far the aluminium has done its job well, though copper could be substituted.

Hopefully I don’t do a follow up on removing the rear bumper and securing those air flaps.

The rats that were giving us grief have gone to rat heaven now. I eventually got rid of them with a large snaptrap loaded with peanut butter, while its fat friend evaded the traps for a number of weeks until we went high end with bait. Note, Rats appear to love Lindt. Please don’t use poison baits unless you have a controlled environment, they are indiscriminate and dangerous to other critters.

Time to clean up the stripped earth straps and re-assemble..

If you are trying to stop rodents I share your pain, good luck to anybody following this DIY!

Note - Be very careful with placement if you are leaving a trap under your bonnet. I have seen a wiring loom practically severed by a caught rat before it expired, chewing through 8 or 9 sensor line cores.