There are many types of proofing or water inhibiting products on the market, and most of them take the form of a waxy substance which can be sprayed into the body sections and cavities to prevent moisture forming rust. The rust proofer is usually applied either by high pressure gun, connected to a Compressor, or by a hand pump, which is usually supplied in the kit.
The best method is to use a compressor, the hand pump used with care will give you the results you want. The advantage of the compressor system is that the ‘Shutz gun’ comes with the extension probe to get directly into the cavities and the rust-proofing agent atomises into a fine mist which travels well into the corners. The hand pump methods tends to leave a thicker coating.
FRONT SCREEN SURROUND AND FRONT ROOF
If you have got a MkIII, this is the place to start, the screen pillars and front roof section are all box sections, and the temperature changes inside the car create condensation inside them which in turn starts to rot the metal from the inside out. You can access the pillars and the front roof from inside the car. At the bottom of the screen pillars, under each side of the dashboard, you will find a hole that leads into the pillar and right up and around to the roof. Push the extension probe of the gun or hand pump up into the pillar as far as it will reach and simply fill the cavity with rust proofer. On Mkl and II cars the screen assembly unbolts but there is no access inside the pillars, the only way it to remove the screen surround and drill two small holes at the base of each pillar.
The main area that rots here is the bottom edge or lip and the outside corners of the skin area (the area you see when the tailgate is closed). The best way to obtain access here is to remove the lock mechanism from the tailgate itself, which will give you about a one inch hole — the extension probe should go right round the corner inside here.
Next remove the boot floor, spare wheel and trim panels above the lights, either brush or spray rust proofer onto the underside of the area that forms the boot shut panel (adjacent to the boot catch) as again condensation forms under here all the time.
You can gain access to the rear wings at the back through the boot area — push the probe along the wing as far around the wheel arch as possible. Give an enthusiastic coating to the cavity at the rear next to the boot floor (where the bumper brackets are) as this generally is a problem area. To access the front part of the back wing and the end of the sill, you may need to remove the rear quarter trim panels — once they are out you will find a nice large hole to spray with rust proofer.
Outer: If it’s a genuine outer it will have three small holes along the bottom outer edge, perfect for the extension probe. Then through the hole in the back inner wing (under the quarter trim panel) you can access the outer sill also, so spray a load in there. At the front, the best thing to do is drill a small hole in the sill end panel (the flat plate on the end of the sill behind the front wheel), make sure there is plenty of proofer around the hole and seal it after with a small hung. Alternatively, the carpet can be carefully removed from inside the front footwell, against the bulkhead side, a small hole drilled here and the carpet replaced.
Inner: If you remove your seats and then very carefully remove the strip of carpet stuck to the inner sill, you will find two elongated holes where you can get plenty of material in, and then stick the carpet back again.
Areas to treat here are the nose / reinforcer section on MkllI cars, and the sidelight areas on Mkl and II cars. On all models, remove the headlights and spray plenty of proofer into the area. On Mklll cars use a paint brush to force as much as possible into the nose section (where the headlight wires run). Finally, try to run the rust proofer around the wheel arch sections between the inner wheel arch assembly and the main wing —the more the better here as it cannot be seen and can save you whole new wings later on.
FRONT VALENCE ON MK3’s
Remove the sidelight assembly and spray in through the aperture