KEEPING THE MICE OUT OF THE DOG HOUSE

Mike Hausner

Photo #1

This spring while getting ready to work on the buggy I discovered that over the winter I had a

couple of unwanted guests take up residence in the garage. More specifically, in the cooling shrouds

of the VW engine. Photo #1 is not a very good picture but you get the idea. They can get in through

the engine air cooling inlet or the gaps between the cooling shrouds and engine block. I planned to

seal up all these entry points. As an added benefit this should also improve engine cooling.

Since my engine has aftermarket tin, it has gaps where the shroud is supposed to seal against

the block. This may not apply to engines using original equipment shrouds.

Photo # 2

To close up these gaps I fabricated aluminum pieces with a mounting tab. The tab will have a

RIV-NUT (or NUT-SERT) installed. These little gems allow you to add a threaded boss to thin sheet

metal parts. They work something like a pop rivet. Photo #3 shows the RIV-NUT installed on one of

the blocking plates.

Photo # 3

I used cardboard to mock up each blocking plate until I was happy with the fit of each part,

then I made an aluminum copy. A hole was then drilled in the cooling shroud and the location

transferred to the aluminum part. This hole was then enlarged to fit the RIV-NUT . You need a

special tool with a threaded stud that goes into the RIV-NUT. It’s the same idea as the pop rivet gun

except its reversed. Instead of the pin going into rivet gun, the threaded stud is on the gun and goes

into the “rivet”. You squeeze the handle and the RIV-NUT deforms and is clamped in place as in

photo # 3. In photo # 4 you see how the plate effectively seals the gap. Photo # 5 shows the three

completed blocking plates needed to seal the gaps on my engine.

Photo # 4

Photo # 5

The cooling air inlet is another opening that needed to be looked at. I had a screen to cover

the air cooling inlet but it was made to fit the early design cooling shroud. The early housing is flat on

the back and it is pretty easy to mount a screen to keep out debris and uninvited guests. The newer

design moves the oil cooler toward the front of the car and out of the airstream going to cylinder

number four. But you probably already know this.

In photo # 6 you can see the different levels on the back of the “dog house” cooling shroud. It

is NOT FLAT. My first thought was to make an aluminum bracket that would follow the contours of

the housing. How hard can it be? Well, my one “bracket “soon became three and I soon decided

that aluminum was not the way to go.

Photo # 6

I decided on FIBERGLASS. When making a part or mold with ‘glass you need to have some

way of removing the part without destroying it. The professionals use a liquid parting agent called

PVA (Poly-Vinyl-something or other). Since I didn’t have the recommended stuff (PVA) I had to use

the next best thing - SARAN WRAP.

The area around the air inlet was to be covered with the plastic wrap to act as a parting agent

for the fiberglass piece. This is not as easy as it sounds as the SARAN WRAP does not like to

cooperate. I finally had to use a spray adhesive on the plastic wrap and this made things somewhat

easier but it was still difficult to place where I needed it.

Photo # 7

Once the plastic wrap was in place I cut several pieces of fiberglass mat and cloth so that I had

enough to cover the area around the air inlet at least three times. The pieces are positioned one at a

time and saturated with resin using a paint brush. Pieces are added around the opening until there

are at least three layers of fiberglass mat and cloth. The cure time varies with the amount of

hardener and the ambient temperature. Due to the cold temperatures at the time I had to use a

work light to add a little heat to help the cure the part. My part was fully cured in about 6 hours.

After initial trimming I decided the part was a little flimsy so I added another layer of cloth to

the outside. In photo # 8 you see the trimmed part with the added layer of glass cloth.

Photo # 8

After final trimming and fitting I marked and drilled the first of three 1/8” pilot holes. I

installed a CLECO in the first hole and proceeded with the second and then the third. The CLECO’s are

a sheet metal clamping device used in aircraft manufacturing and are very handy when working with

parts like this. Photo # 9 shows the part held in place with three 1/8” CLECO’s. With the holes

located I drilled the housing for the RIV-NUTS.

Photo #9

The final step is to apply plastic wrap (again) to the dog house and using a liberal amount of

aquarium grade RTV, attach aluminum screen to the backside of the fiberglass part. With this done

the assembly is then fastened to the housing using three 10-32 screws.

Photo # 10

Here you see the finished part. This should keep the mice out of the dog house. Any

questions or comments you can e-mail me at: mikehausner@aol.com