SECRETS OF RUSTPROOFING

TECH TOPICS

SECRETS OF: CORROSION PREVENTION

In the last issue we covered the winter ‘laying up’ of your classic – an ideal time to address long term preservation. Follow Craig Talbot’s tips to achieve automotive prolonged existence…

WORDS & PHOTOGRAPHY: CRAIG TALBOT

Rust is the enemy of older steel bodied cars, it's a process that converts metallic iron to iron oxide which is the orange flakes so commonly seen on older cars. It can be a difficult process to stop in less-than-ideal conditions, such as high humidify or exposure to road de-icing salts in the winter. Once rust has gained a toehold on metal it is difficult to stop its spread, so it is vital for older cars to protect the body from rust before it starts. In this guide we will be assuming that the car is free from rust, and we will be protecting it from rust before it starts, rather than treating rust that is already present.

RUSTPROOFING FLUIDS

There are multiple fluids available for protecting and treating a car, a very broad division is fluids that are to be sprayed into protected areas of the vehicle, such as into box sections and sill interiors, and fluids that are sprayed onto panels and components are not enclosed, such as floor pans and suspension components. Some types of fluids result in a thin film that dries to the touch, these would be used in places that are either visible or are handled. Other types of fluids do not set and remain tacky. These cannot be painted over but have the advantage of being self healing if they are disturbed or the substrate cracked. Self healing is particularly useful in places where access is difficult, such as internal sections, or places behind trim panels, such as door shells.

Some fluids for internal sections are typically wax based and are often amber in colour, while others are not waxed based and are more closely related to paint type products. These »

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The waxes need to be heated gently to ensure they can flow and be sprayed. Heating in a pan of water is the safest method and ensures that the fluid is heated slowly. The cap should be loosened to allow for expansion. The wax is flammable, so should never be heated over an open flame, such as a BBQ or gas stove. Heating until the wax sounds like water when the can is shaken in sufficient, or a temperature of approximately 40-50°C.

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I used the Lemmer RP-460HD rustproofing gun with the various attachments. Nozzles are available to apply the fluids to an exterior panel, to interior panels and inside various shaped cavities. A 360 nozzle useful for the interiors of sills or box sections, a fan nozzle, two quick connect nozzles and larger spray nozzle is provided. The standard hose length is 36" and alternative length hoses are available. The user’s choice of air quick connect needs to be provided to attach an air supply to the gun. Here is a demonstration (using water) of the spray patterns from the various nozzles that attach to the gun with a quick connect. Air pressure is typically around 30-40 psi, depending on the viscosity of the rustproofing fluid being sprayed. Pressure that is too high will over-atomize the fluid and create mist and overspray, rather than delivering the fluid onto the car. When spraying the rustproofing fluid, proper personal protective equipment needs to be worn, such as gloves and breathing protection. Always read the directions for the particular fluid you are using.

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This is a fan nozzle, for covering a larger area, but not laying as thick a film on the car. This can also be used in tighter areas where it's not possible to back up from the car a long distance.

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The fan tool is useful for the inside of door shells, and interior portions such as over a rear wheel arch. The 360 nozzle is for spraying the interior of box sections and is available is various lengths of tubing. Standard length is 36". Here using the water spray it can be seen how the spray can cover the interior of a internal section. This is a closeup of the 360 nozzle showing the cuts in the tip that create the pattern.

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Here the door panel has been removed from the car, and in this case the factory used tape, rather than plastic sheeting as the interior waterproofing. Most Series 1-3 XJ cars and XJS use plastic sheeting. The waterproofing needs to be pulled aside for access to the door cavity. A fan tool is handy for spraying the bottom of the door shell and ensuring that wax penetrates between the door shell and door skin. Be certain the drain holes are clear and do not become filled with wax. Also be aware that wax will likely drip from the bottom drain holes, so put down protective sheeting over your workspace.

When removing the door panels on many Series 1-3 XJ cars the interior pulls are often attached to the door shell with a large pozidrive screw. This is usually concealed with a chrome finisher that simply pushes back to expose the screw. The map pockets and /or armrests are typical mounted on fasteners that slide in a slot and then lift free. Be very careful of prying on trim pieces thinking they are mounted on clips, as they are often not. Take your time to carefully look at the trim pieces to determine how they are attached to the door.

“...wax-based coatings will need an inspection every year, and recoating every few years, depending on how the car is driven and the environment in which it is driven.”

internal application fluids come in different viscosities and can be intended to be applied in various ways. Some come in spray cans and can have an attachment nozzle to direct the fluid into various cavities, such as door shells or internal surfaces of sills.

Fluids can come in various viscosities, and for those for those used for internal sections it can be advantageous to have a wicking fluid. This is used on the backside of rear wheel arches for example, where the wheel arch is formed from two pieces of sheet metal

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spot welded together. Water and road salt can penetrate between the spot welds, leading to rust. If access can be gained between these panels, then a wicking fluid can be injected, and this will penetrate between the layers of welded metal. Care must be taken with fluid choice, as the fluid will wick through the spot-welded joints and will be visible on the outside of the car. This excess that drips through will need to be cleaned off with the recommended solvent, which is typically mineral spirits. This may need to be repeated several times, for example if the car is sprayed in a cool day in the winter and is a black car parked in the sun in the summer the panels will get hot, and the fluid will migrate. Similarly, a black fluid should not be used on a white car!

For external panels, such as above the IRS or for coating exposed fuel tanks in small saloons, a heavier bitumen-based fluid is a available. This fluid typically is black and can be used for panels directly exposed to road spray. It will remain in place much more readily than the lighter fluids used for internal panels.

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Ensure access to all areas along the door, as there are obstructions within the door, such as internal stiffener panels and brackets for mounting window mechanisms.

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When spraying inside the door, ensure that the glass does not get sprayed. Removing the wax from the glass and glass wipes can be a difficult task, so much easier to ensure they do not get coated.

Carpets can be peeled back to allow access to the A pillar and door hinge area. Grommets can be removed gently, and rustproofing fluids sprayed inside to ensure the door pillars are protected. When finished spraying ensure the trim is properly seated and replaced. Ensure that all interior trim is protected from accidental spills and drips.

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The A pillar and door hinge areas can also be sprayed with some of the trim in place, it will depend on the particular car.

This fluid is not a wicking fluid, so should not be used for internal panels, and should not be used for door shells.

The wax-based fluids are different than the rubberized undercoating type of sprays that are available to apply to the exterior surfaces, such as floor pans. Those are intended as a more permanent coating, but surface preparation is very important. If the edges are not sealed properly, then the water can get under the coating and is trapped, accelerating the formation of rust. The wax-based coatings will need an inspection every year, and recoating every few years, depending on how the car is driven and the environment in which it is driven. A car that is parked for the winter will need recoating much less frequently than one driven daily in a Canadian winter with hard packed pieces of snow, ice, gravel and salt »

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Upper A pillar and cowl areas can usually be accessed through the hinge aperture.

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In the engine bay, unused captive nut holes are used for access to the front chassis rails. Here the 360 nozzle is used to provide a good coating inside the box section.

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The 360 nozzle tool is pushed inside the forward chassis rails as much as possible.

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At the front of the car, the inside of the front bumper can be sprayed to prevent galvanic corrosion between the aluminum crash beam and steel fasteners that retain it to the body. Care should be taken to ensure that the plastic cladding isn’t coated.

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Moving to the underside of the car, the interior sections of the chassis rails need to be protected. A combination of the fan and 360 nozzle tools are useful here.

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At the front of the car, the upswept sections of the chassis should be coated. The jacking point is visible as well, these should be coated inside and out to ensure these rust prone sections are protected. At the rear, the box sections over the IRS need to be accessed and injected with wax. Be careful not to get overspray on the exhaust pipes or muffler, as the hot exhaust components are a fire hazard. The earlier style radius arms are used on my Daimler, but the enclosed style arms used on some XJ cars should be treated on the inside, as these are areas prone to rust. Box sections above the rear jacking points are vulnerable to filling with road debris, ensure these are cleaned out before spraying rustproofing wax inside.

being thrown up by the wheels against the body panels. Applied correctly, the rubberized undercoatings or stone guard type coatings can last the life of the car and are considered more than just rustproofing. A visit to your local body shop supply store will acquaint you with the range of products available, as well as the types of packaging. Some materials come in various size containers intended to be used in a spray gun, and others are available in aerosol cans. Depending on the size of the vehicle and the amount of rustproofing to be done, the aerosol cans may prove to be more convenient than buying an air compressor and spray gun. Here are some of the steps taken to apply rustproofing to a Daimler DS420. n

Special thanks to: Lemmer Spray Systems for the use of the spray gun. 4624 12th Street NE, Calgary, AB T2E 4R4 Canada. www.lemmer.com

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Further to the rear, ensure the chassis rails have sufficient wax injected to protect them. There can be different levels of the formed chassis rails, so ensure that all areas are sprayed. The 360 nozzle on a long hose can be useful to ensure complete coverage.

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The Daimler has reinforcing plates on the lower wishbones, these need to be protected.

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Moving to the outer perimeter, the sills of the Daimler have a series of body plugs along the underside of the sills. These can be gently removed, and access gained to the interior of the sills and are useful injection locations.

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The body plugs are a sung fit to ensure that they seal out water and road debris. Remove them carefully and replace any if they break.

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The plugs are a hard type of plastic, a sharp, but gentle tap will seat them back in place after spraying. The removed body plug hole is used to spray rustproofing fluid inside. Ensure an adequate coat, but not flooding the interior. Especially for a black car, when sitting in the sun the fluid will want to creep out as it heats. Spray enough to ensure a protective coat, but not so much that the car is continuously dripping.

Many types and kinds of cavity wax are available, if you don't have an air compressor available and don't wish to spend up to several hundred dollars on a spray gun outfit, the waxes area available in a number of brands and types in spray cans. Application is very similar as with the air powered gun, and extension wands are also available to enable the spray cars to reach inside sills.