Previously, Ford had been recommending Motorcraft PM-12 and PM-13 to restore corrosion protection to areas such as the backsides of panels, the exterior of frames, and body or frame cavities. PM-12 is a low-temperature, anti-corrosion coating. PM-13 is a solvent-borne undercarriage/blackout paint.
Ford now recommends using Motorcraft Rust Inhibitor PM-24A or 24B to restore corrosion protection to areas such as the backsides of panels, and Motorcraft Premium Undercoating PM-25A or 25B to restore corrosion protection to areas such as the exterior of frames and the backsides of body panels. Products identified with an "A" are supplied in aerosol containers and products identified with a "B" are supplied in bulk, non-aerosol containers. PM-24 and PM-25 are both Motorcraft part numbers, available from Ford dealerships.
The aerosol products work well for exposed repairs, the company said. The non-aerosol products can be applied using spray equipment with a wand attachment. Use a flexible wand or steel tube wand to reach into cavities. Special tools, specifically a rust-inhibitor installation kit and an undercoating spray gun, are available from Ford for application of the non-aerosol form of these corrosion protection products. Comparable spray equipment also may be used.
Rust Inhibitor PM-24 and Undercoating PM-25 are wax-based products and must be thoroughly stirred or shaken before applying to the vehicle. These products should be stored at temperatures above 68 degrees to avoid thickening of the material. If the product has been left in a cold environment, Ford recommends placing the container in hot water for five to 10 minutes. Don't let water reach the cap of the container.
PM-25 is applied in locations such as the undercarriage, hidden areas and wheelhouse areas, as needed. It duplicates the OE look for frames and underbody use and can be applied over a light coat of PM-24 if desired. PM-24 is light brown and has a thin consistency when used at the recommended temperature. PM-25 is black and has a thicker consistency than the PM-24. Neither PM-24 nor PM-25 completely dries to the touch.
Ford no longer recommends using PM-12 anti-corrosion coating. PM-13 is still available but is recommended only as an undercarriage paint, such as for touch-up of trailer hitches or suspension arms.
Application
To avoid personal injury, always refer to material safety data sheets when handling chemicals and wear protective equipment as directed. Recommended protective equipment for PM-24 and PM-25 include a vapor respirator, chemically resistant gloves and face/eye protection.
When restoring corrosion protection using PM-24 or PM-25, metal surfaces must be free of oil, dirt and other foreign material. Thoroughly clean and degrease metal surfaces with a wax and grease remover. Body panels installed during collision repair that will not be accessible after assembly should be cleaned before installation to improve the adhesion of anti-corrosion materials that are applied when assembly is completed.
Protect adjacent areas of the vehicle from overspray. Avoid applying corrosion protection to mechanical and electrical parts, electric motors, speakers, door locks and drain holes. Excessive amounts of the material can plug drain holes and cause water drainage problems. Do not allow the material to contact restraint system parts or exhaust system parts.
When using spray equipment to apply PM-24B, the air pressure setting for the applicator gun should be 65-75 psi. Use a long wand when spraying enclosed areas. Insert the wand as far as possible into the access hole. Depress the trigger, wait two to three seconds, and slowly pull the wand out of the access hole. The spray nozzle provides a 360-degree spray pattern.
When using spray equipment to apply PM-25B, the air pressure setting for the applicator gun is 80-90 psi. The non-aerosol container of PM-25B will attach directly to the dispensing gun of the Ford special undercoating spray gun tool. The applicator sprays in a fogging pattern. Depress the trigger, wait two to three seconds, and slowly pull the wand to ensure that the area is completely fogged.
For best results, the vehicle should be at room temperature. Apply light mist coats. PM-24 and PM-25 will displace moisture. Do not use high-pressure water spray cleaning on the treated underbody area for 24 hours following application of the corrosion protection product.
Ensure that horizontal surfaces are well protected because they are more susceptible to corrosion. Clean up any overspray with a mild solvent such as mineral spirits.
