How to Paint a Plastic Engine Cover

A plastic engine cover is an ideal part for a striking special effect finish. Flip-Flop, Candy, pearl or another special effect can turn an ordinary black plastic cover into an eye-catching feature in the engine bay. For a high-quality and durable result, however, the most important steps are correct preparation of the plastic surface and the use of a suitable plastic primer.

What type of part is this guide intended for? This procedure is designed primarily for common decorative plastic engine covers. If you want to paint a metal valve cover, a component close to the turbocharger or exhaust manifold, or another part exposed to significant heat, the paint system and products must be selected according to the material and its actual operating temperature.

1. Remove and thoroughly clean the engine cover

Whenever possible, remove the engine cover before painting. This makes the work much easier and significantly reduces the risk of paint or solvents reaching surrounding engine components.

Also remove badges, rubber grommets, seals and any other parts that should not be painted. Carefully mask anything that cannot be removed.

Engine covers are often contaminated with oil, grease, dust and products previously used to clean or dress the engine bay. Thoroughly wash the surface first and allow it to dry completely.

2. Degrease the surface

Before sanding, we recommend removing grease and other contaminants with a suitable degreaser. For example, you can use HB Body 770 Antisil Silicone Remover / Degreaser Spray.

This first degreasing step before sanding is important – you do not want grease, silicone or other contaminants to be worked deeper into the plastic surface by the abrasive.

3. Lightly abrade the plastic

A smooth plastic surface does not provide ideal adhesion for paint. Lightly and evenly abrade the entire area to be painted using a fine abrasive or sanding pad.

For smooth plastic, approximately P600–P800 can be used as a general guide. The aim is not to remove a significant amount of material or change the shape of the cover, but simply to remove the gloss and create a uniformly matt surface.

Do you want to preserve the original plastic texture? Work very gently on textured engine covers. Excessive sanding can smooth the original texture in some areas, and these differences may become even more visible after painting.

4. Degrease again before applying primer

After abrading the surface, remove all sanding dust and thoroughly degrease it again. Before applying the next product, the plastic must be completely clean, dry and free of dust.

For more information about preparing different types of surfaces, see our guide How to Prepare the Surface Before Painting.

5. Apply plastic primer

Apply BOLL Plastic Primer 400 ml Spray to the clean and abraded unpainted plastic. This transparent adhesion primer improves the bond between the plastic surface and the subsequent paint layers.

Apply the primer in thin coats and follow the application procedure and drying times specified for the product. The aim is not to build a thick layer as with a filler primer – the primary purpose of the plastic primer is to ensure proper adhesion of the paint to the plastic.

Basic paint system for a plastic engine cover:
clean plastic → abrade → degrease → plastic primer → basecoat → special effect paint → clear coat

6. Want a smooth finish? Use a filler primer

This step is not always necessary. If you want to preserve the original texture of the plastic engine cover, you can continue directly with the recommended paint system after the plastic primer has been correctly applied.

If the cover is rough, scratched or you want to achieve a smooth finish similar to painted body panels, you can level the surface with HB Body P360 2K Grey Filler Spray.

Once fully cured, sand the filler to the required smoothness using approximately P400–P600. Before applying the basecoat, thoroughly remove all sanding dust and degrease the surface again.

7. Choose the correct basecoat

Once the plastic has been correctly prepared, the colour system is the same as for other properly prepared surfaces. Always select the basecoat according to the special effect you want to achieve.

For most Flip-Flop effect paints, Candy Pearl, Hologram and many pearl effects, use PMcolours Black 1K Basecoat Spray.
For transparent Candy paints, use a reflective metallic basecoat, most commonly SilverTouch.
For selected red, orange and yellow Candy shades, you can also use SolarGold.
For Ghost Pearl paints, use PMcolours White 1K Basecoat Spray.

Apply the basecoat in several thin, even coats until you achieve a continuous surface with uniform coverage and no exposed areas.

8. Apply the special effect paint

Once the basecoat has flashed off correctly, you can apply your chosen special effect. Thanks to its shape and position, a plastic engine cover is well suited to a wide range of striking colours and effects.

You can choose from, for example:

Flip-Flop effect paints in spray cans – change colour depending on the light and viewing angle,
Candy paints in spray cans – transparent colours with exceptional depth,
Candy Pearl in spray cans – Candy appearance combined with a fine pearl effect,
pearl effect paints in spray cans – striking metallic and pearl effects,
Ghost Pearl in spray cans – a subtle effect that becomes particularly visible in direct light,
Hologram – a rainbow effect that reacts to direct light,
holographic glitter paints – for an intense sparkling effect.

The exact number of coats, flash-off times and required basecoat depend on the selected special effect paint. As a general rule, several thin and even coats will produce a better result than one heavy coat.

9. Finish with a clear coat

PMcolours special effect paints are basecoats and must be protected with a transparent clear coat. The clear coat enhances the depth and final appearance of the effect while protecting the surface during normal use and cleaning of the engine bay.

For maximum mechanical and chemical resistance, we recommend 2K PRO Gloss Clear Coat 400 ml Spray. This is a true two-component clear coat with a hardener activated directly inside the spray can.

Once the 2K spray has been activated, its usable pot life is limited. Prepare the entire project before activation and always follow the instructions provided with the product.

Pay attention to the temperature of the engine cover

Standard PMcolours special effect paints are heat resistant up to approximately 100 °C. A typical decorative plastic engine cover is generally not an extremely heat-stressed component, but you should still consider its actual location and operating temperature before painting.

Important: this paint system is not intended for components whose surface temperature may remain above approximately 100 °C. For metal valve covers, components near the turbocharger or exhaust system, and other parts exposed to high temperatures, first determine the actual operating temperature and use a suitable paint system.

Complete process at a glance

Remove the plastic engine cover and clean it thoroughly.
Remove grease, silicone and other contaminants.
Lightly and evenly abrade the entire surface.
Remove sanding dust and degrease the surface again.
Apply plastic primer.
If you want a smooth finish, apply filler primer and sand it after curing.
Apply the correct basecoat for the selected effect.
Apply the special effect paint in several thin coats.
Finish with a high-quality clear coat, preferably 2K.
Allow the entire paint system to cure sufficiently before refitting the cover.

With a plastic engine cover, the durability of the finished paintwork depends primarily on a clean, correctly abraded surface and a high-quality plastic primer. Once the plastic has been properly prepared, you can apply the same basecoat, special effect paint and clear coat system used on other paintable parts to create a striking Flip-Flop, Candy, pearl or other special effect finish.

If this is your first time painting with a spray can, we also recommend our guide How to Achieve a Perfect Spray Paint Finish.