Repair of minor body damage (BMW 5 Series E28)

For more detailed information on body repair work, please refer to the special "Car Body Repair Guide".

Repair of minor body scratches

If the scratch is superficial and does not reach the metal panel, the restoration procedure is very simple. Lightly rub the damaged area with paint restorer or very fine lapping paste to remove loose paint particles and remove the protective wax layer from the surrounding surface. Rinse the treated surface with clean water.

Using a thin brush, apply a coat of exterior car paint to the scratch; apply paint in thin layers until the paint surface inside the scratch is flush with the surrounding undamaged paint. Allow the fresh paint to cure for at least two weeks, then disguise the transition from the newly painted surface to the old paint as much as possible by rubbing it with paint restorer or very fine lapping paste. Finally, apply a protective wax coating.

If the scratch has reached the metal of the body, which may cause corrosion of its metal, the restoration procedure will be different from the above. Use a pocket knife to remove loose rust particles from the bottom of the scratch, then coat the scratch with a rust inhibitor to prevent further corrosion. Use a nylon or rubber applicator to fill the cavity of the scratch with filler paste. If necessary, to thin the paste when filling narrow scratches, mix it with cellulose solvent. Before the paste hardens, wet your finger, wrapped in a soft cotton cloth, with cellulose solvent and quickly smooth the filled surface of the scratch; this will provide a slight concavity to the treated surface. The scratch can now be painted over as described above in this Section.

Repair of deformed surfaces

Deep dents are first pulled out to give them a shape as close to the original as possible. Complete restoration of the shape is impossible, since the metal of the damaged panel stretches under the impact load. The optimal level is to give the deformed surface a level approximately 3 mm below the level of the surrounding undeformed part of the body. In the case of a very shallow dent, there is no point in trying to pull the panel out at all. If there is access to the inside of the deformed area, the shape can be restored by tapping the dent with a hammer with a wooden or plastic striker. When tapping, to dampen the hammer blows and thereby prevent a larger than necessary section of the panel from bending, press a wooden block of suitable size tightly against the damaged area from the outside, which will absorb the hammer blows and thus prevent the appearance of a "belly" on large areas of the body.

In the case where the deformation is in a section of the body that has a double structure, or if access to the back of the dent is not possible for another reason, another pulling technique should be used. Drill a series of small holes inside the deformed area, especially in its deepest part. Then screw long screws into the holes so that they are securely fixed in the metal. Now the shape of the panel can be restored by pulling out the dent, grasping the protruding heads of the screws with pliers.

The next step is to remove the paint from the damaged area and for an inch or so around it. This is most easily accomplished with a wire or abrasive attachment in the chuck of a power drill, although it can be done by hand with sandpaper just as effectively. The final step in preparing for filler is to scratch the bare metal surface with a screwdriver or file, or alternatively, drill a series of small holes into the damaged area. This will ensure that the filler will adhere best to the metal.



To complete the repair, please refer to the section on puttying and painting.

Repair of holes caused by corrosion and punctures

Remove all paint from the damaged area and 2.5 cm around it, either by hand or with a drill attachment. You can then determine the extent of the damage or corrosion and decide whether it makes sense to repair or replace the entire panel (if possible). New panels are not as expensive as many people think, and it is often faster and more cost effective to replace a panel than to repair large rusted areas of the body.

Remove all trim pieces from the damaged panel except those that can serve as templates to restore the panel to its original shape (such as headlight housings, etc.). Next, use tin snips or a hacksaw blade to remove any heavily corroded or loose pieces of metal from the panel. To create a slight depression for the filler, fold the edges of the hole inward.

Remove any powdery rust from the remaining metal surface. Treat the affected area with a rust inhibitor; also treat the back surface if you have access to it.

Before you can begin filling, you need to block off the hole in some way. This can be done with aluminum or plastic mesh or aluminum tape. For larger holes, aluminum or plastic mesh or fiberglass matting is best. Cut a piece of mesh roughly the right size and shape, then lay it over the hole so that its edges are below the level of the surrounding undamaged body panel surface. The mesh can be held in place with a few globs of filler placed around its perimeter.



Aluminum tape is used to block small or very narrow openings. Unwind a piece of tape of the required length from the reel, cut it with scissors to approximately the required shape, then remove the paper sticker protecting the adhesive layer (if there is one), and apply the tape over the hole, blocking it. If one piece of tape is not wide enough, you can apply several pieces overlapping each other. Carefully smooth the edges of the tape with the handle of a screwdriver, ensuring that it adheres securely to the back of the metal surrounding the hole.

Body repair - puttying and painting

Before proceeding with the procedures in this Subsection, please review the information in the previous ones.

There are many different types of putty available, but for this type of work, the best are the patented kits, which consist of a tin of putty and a tube of hardener. To ensure smooth application of the paste while maintaining the desired contour, use a wide flexible plastic or nylon applicator.

Mix a small amount of filler on a clean piece of cardboard or plywood. Measure the ingredients carefully, following the manufacturer's instructions on the package, as adding the wrong amount of hardener can cause the mixture to harden too quickly or too slowly. Using an applicator, apply the prepared filler to the surface prepared for filling; to give the surface the desired level and contour, move the applicator across it. When the contour of the surface being treated is close to the original, stop applying the filler, since if you apply it too much, it may become "sticky" and start sticking to the applicator. Continue applying thin layers of filler at 20-minute intervals until the filled surface begins to protrude slightly above the undamaged area of the panel.



After hardening, excess putty can be removed with a metal strip or file. Next, the putty surface should be processed with waterproof sandpaper of gradually thinner grades, starting with No.40 and ending with No.400. To give the treated surface an absolute plane, always wrap the paper around a flat rubber, cork or wooden block. During the processing, constantly wet the waterproof paper with water. This will ensure absolute smoothness of the surface at the final stage of grinding.

Once this stage of work is completed, the surface being treated should be surrounded by a ring of bare metal, which in turn should be outlined by the edge of good paint that has been ground down to nothing. Rinse the treated surface with clean water, removing all dust from it that has formed as a result of grinding.

Spray a thin layer of light primer over the entire surface to be treated - this will help to visually identify all treatment defects. Eliminate all the flaws by covering them with fresh putty and treat the surface again with sandpaper. Repeat this procedure until you achieve a result that satisfies you. Rinse the finally treated surface with clean water and let it dry completely.

The surface is now ready for painting. Work with aerosol should be carried out in a warm, dry, windless and dust-free atmosphere. These conditions are easiest to meet when working in a large closed room, but if you are forced to work outdoors, you must carefully choose the day of painting. When working indoors, wet the work area with water to knock down dust in the air. If you are painting a separate body panel, cover the surrounding panels; this will help to minimize the effect of slight differences in tone between the old and new paint. You should also cover up the body trim details (chrome trims, door handles, etc.). To cover, use duct tape and several layers of newspaper.



Before you begin painting, shake the aerosol can well, then test it on a test surface to achieve the desired level of skill. Cover the surface to be treated with a thick coat of primer, achieving the thickness by applying several thin coats rather than one thick one. Sand the surface with 400-grit waterproof sandpaper until it is perfectly smooth. During the process, periodically wet the surface and the waterproof paper with water. Finally, rinse the surface again with clean water and allow it to dry completely before applying paint.

Apply the top coat of paint, again achieving thickness by successively applying several thin coats. Start painting from the center of the surface to be restored and move in circular motions toward the periphery until the entire surface and about 5 cm of surrounding old paint are painted. After 10-15 minutes from applying the last coat of paint, remove the covering material from adjacent panels and trim elements.

Allow the paint to dry for at least two weeks, then use paint restorer or very fine rubbing paste to mask the transition from the newly painted surface to the old paint as much as possible. Finally, apply a protective wax coating.

Plastic components

As car manufacturers increasingly use plastic body parts (such as bumpers, spoilers and in some cases even large body panels), repairing more serious damage to these elements is either entrusted to specialists in this field, or to a complete replacement of the elements themselves. Repair of such damage by the car owner is practically impossible due to the significant cost of equipment and materials required to perform it. The repair technology is based on making a groove in the plastic along the crack line using a sharpening attachment on an electric drill. After that, the cracked part is welded using a hot air gun, which melts the plastic filler rod inserted into the groove. Then the excess plastic is removed and the surface is sanded until smooth. It is important that the plastic filler rod is selected correctly, since the body components can be made of different types of plastic (polycarbonate, ABS, polypropylene, etc.)

Less serious damage (nicks, abrasions, minor cracks, etc.) can be eliminated by the car owner himself using a two-component epoxy putty. Mixed in equal proportions, it is applied in the same way as putty for metal surfaces. It usually sets in 20 - 30 minutes, ready for sanding and painting.

If the owner replaces the element completely on his own, or restores it with epoxy putty, he faces the problem of finding a suitable paint that is compatible with the type of plastic the part is made of. At one time, the use of a universal paint for plastic components was impossible due to the variety of types of plastic used. Standard paints generally do not bond well to plastic or rubber surfaces. Now, however, kits for finishing plastic body parts have appeared, which include a primer for pre-treatment, a secondary primer and a top decorative paint. Kits are usually accompanied by comprehensive instructions, but in general the technology is that first a preliminary primer is applied, which must dry for at least 30 minutes. Then a secondary primer is applied, and after it dries for an hour, a layer of specially selected exterior paint is applied. The result is a properly painted component where the paint will be flexible enough to bend with the plastic or rubber, which is not the case with standard paint.