Anti-corrosion compounds
The load-bearing hollow profiles of the body, the bottom, the lower parts of the doors, pillars, as well as the joints of body parts, including the places of spot welding, are most susceptible to corrosion. Corrosion develops most rapidly in hidden cavities and lower parts of the body when moisture, dirt, salts and acids get on the surface.
Some private causes of corrosion and ways to eliminate it are given in table. 37. During the operation of the car, additional protection of internal surfaces and hidden cavities of the body is required (application of special anti-corrosion compounds) and joints of parts - by applying sealing mastics.
The materials used for anti-corrosion treatment are listed in Table. 38.
Autopreservative Movil is used for the treatment of hidden cavities. Cavities are recommended to be treated at least every 1-1.5 years. Movil can treat surfaces previously coated with nigrol or other oils, as well as rusty surfaces.
Protective lubricant NGM-ML is used for processing hidden cavities. The cavities of new cars are treated with this material.
Protective film coating NG-216B is used to cover parts of the car under the body.
Anti-noise mastic, bituminous BPM-1 is used to protect against corrosion of the bottom of the body and to reduce vibration noise. The mastic is applied by spraying or manually with a thickness of 1.0-1.5 mm.
Plastisol D-4A is used for sealing welds on the outer areas of the body.
Non-drying mastic 51-G-7 is used to seal the joints of body elements.
In hidden cavities, the anti-corrosion agent is sprayed by air or airless spraying. Air spraying requires compressed air with a pressure of 5-8 kgf/cm2, spray gun with reservoir, hoses and gun extensions. The best quality of the coating is achieved with airless spraying at a pressure of 90-100 km/cm2, which allows you to spray materials of significant viscosity.
Preparation and anti-corrosion treatment of hidden cavities
Due to the use of sophisticated technological equipment and the need for high-quality work, it is recommended that the processing of hidden cavities be carried out only at car service stations.
The sequence of treatment with anti-corrosion compounds:
- 1. Install the car on a lift, remove parts and upholstery that prevent access to hidden cavities.
- 2. Rinse with water at 40-50°C through technological and drainage holes hidden cavities (tab. 39), bottom of the body, wheel arches until clean water flows out. At the same time, the pivot windows must be closed, the lower ones must be raised.
- 3. Remove water that has got into the passenger compartment and trunk, blow out all hidden cavities and other places where anti-corrosion compounds are applied with compressed air.
- 4. The car is driven into the chamber for applying an anti-corrosion compound and put on a lift. Spray the anti-corrosion compound into the places indicated in fig. 202, 203 and 204.
- 5. Lower the car from the lift and clean the front surfaces of the body from dirt with a rag soaked in white spirit.
Restoration of a complex anti-corrosion and anti-noise coating of the bottom of the body and wheel arches
During the operation of the car, the coating on the bottom of the body is damaged and erased from the effects of gravel, sand, salt, moisture. Bare metal corrodes.
At the car factory, BPM-1 mastic was applied to the lower surface of the body base and spars for sound insulation and protection against corrosion.
Before restoring the coating, install the car on a lift, carefully inspect the bottom of the body and identify defects in the coating. The bottom of the body is cleaned of dirt, rust is removed with a spatula or sandpaper. Blow the bottom of the body with compressed air. Rust remover can be used to remove rust "Omega 1" or auto rust converters.
Install the car on a lift in the mastic chamber and remove the wheels. They close the brake drums and discs with protective covers, insulate the driveline, muffler, cables and other places that cannot be treated with mastic with thick paper and adhesive tape.
Degrease with a rag soaked in white spirit, cleaned to metal places. GF-073 primer is applied to the places cleaned to the metal with a sprayer or brush and kept for 5-10 minutes.
On defective areas by spraying or by hand (brush and spatula) BPM-1 mastic is applied with a layer of 1-1.5 mm.
In the cold season, the mastic is kept in a warm room before use until the temperature rises below 20°C. The thickened mastic is diluted with xylene up to 3% by volume.
Paintwork contaminated with mastic is cleaned with a rag soaked in white spirit.
The mastic is dried at a temperature of 100-110°C for 30 minutes or at 18-20°C for at least 24 hours.