Restoring the appearance of an outboard motor is not just an aesthetic whim of the owner of the water transport, but an important part of maintenance. Aggressive aqueous environment, constant contact with salt or fresh water, rocks and sand strikes cause the protective coating on the lower unit and casings to collapse, if not stopped in time, it can spill over to functional units, leading to costly repairs or complete replacement of the unit.
The painting process requires careful preparation and the right choice of materials, since ordinary car enamels may not withstand specific operating conditions. In this article, we will discuss in detail how to properly prepare the surface, what soils and paints to use for the construction of the car. aluminum and steel alloys, as well as how to achieve factory quality coating in garage conditions.
Many water-engineers underestimate the importance of primary metalworking before applying the finish layer. However, it is the quality of preparation that determines how many seasons a new paint will last without chipping and bloating. Let's look at the key steps in this process so that your engine shines again and its resource is not affected by poor quality intervention.
Selection of paint materials for aquatic environment
The first and most critical step is to get the paint chemistry right, and the standard aerosol sprays from the building store, which are designed for fences or radiators, are not suitable for outboard motors, and water, especially salt water, has high electrolytic activity, which triggers rapid oxidation processes. epoxy Soils and two-component polyurethane enamel are an uncontested standard for marine applications.
When choosing a material, you need to pay attention to its elasticity after drying. The engine is subjected to vibrations and thermal expansion of the metal. If the paint is too rigid and brittle (fragile), it will inevitably be covered with a network of microcracks through which moisture will reach the metal. Marine Grade, which contain corrosion inhibitors and have high adhesion to non-ferrous metals.
The color scheme is also not only important from an aesthetic point of view: dark colors such as black or dark blue are more heated in the sun, which can affect the temperature of the engine in statics. However, it is dark pigments that often have better cover and are less susceptible to fading under the influence of ultraviolet light.
- 🎨 epoxy - a mandatory basis for the creation of an anticorrosion barrier on aluminum.
- 🛡️ Polyurethane enamel - provides resistance to mechanical damage and chemicals.
- 🌊 Anti-fouling compounds - Used only on the underwater part of the lower unit for protection against fouling.
⚠️ Warning: Never use water-based paints (acrylic, latex) to paint the outer parts of the outboard motor. They are hygroscopic and pass moisture to the metal, accelerating corrosion.
If you can’t find specialized marine paint, use car two-component enamel for discs or calipers – it has high heat resistance and chemical inertness.
Dismantling and primary surface cleaning
A high-quality painting of a outboard motor is impossible without the complete or partial dismantling of attachments. Attempting to paint the engine "in place", pasting candles, sensors and badges with paint tape, almost always leads to unsatisfactory results. The paint will flow under the seals, and in hard-to-reach places there will be rust pockets that will continue to destroy the metal under the new layer.
You should start with a thorough washing of the unit. Use special cleaners to remove oil film, traces of fuel and algae. Regular Kalosha gasoline or white spirit is well defatted, but for old contaminants it is better to use a specialized one. car-chemistryAfter washing, the surface should be completely dry and clean.
Then there's the mechanical removal of the old paint coating, and if the old layer is strong and not bloated, you can just wrap it up, not remove it completely, but if you see corrosion or paint flakes away, you need to clean the metal to the base, and it's convenient to use a petal-circle angle grinder or an orbital grinder.
Pay special attention to the areas around the exhaust pipe and the lower unit, where the temperature and the impact of water is maximum. The cleaning should be done carefully, so as not to disturb the geometry of thin-walled elements. After machining, the surface becomes matte and rough, which ensures maximum adhesion of the future soil.
Corrosion control and grinding
Once the main layer of paint is removed, it is often found that the metal is already corrosive. You can't just paint the rust, it will continue to eat the metal under the new enamel. You have to chemically or mechanically treat the affected areas. Aluminum, which is the stuff that most lower units are made of, has a point corrosion that needs to be cleaned to the pure metal.
The ideal tool for finishing is sandpaper, starting with abrasive P80-P120 to level the surface, and then switching to P240-P320. Smaller abrasives are not recommended before primer, as too smooth surface can worsen the adhesion of the soil.
If rust has penetrated deep into the metal structure or has formed shells, rust transducers may be required, but you need to be careful with them: many of them contain orthophosphoric acid, which is active to aluminum. After treatment with the converter, the surface must be neutralized and thoroughly washed.
☑️ Preparation for grinding
It is important to understand that aluminum They're instantly oxidized in air to form a thin film, which is normal, but the oxide layer also needs to be removed just before applying the soil to allow the materials to bond chemically.
Printing: the basis of durability of the coating
The substrate is the foundation of your paint coating, and it's the layer that protects the metal from corrosion and creates the base for the finishing enamel. For outboard motors, the best choice is two-part epoxy soil, which creates an impermeable barrier to moisture and oxygen, completely insulating the metal from the aggressive environment.
You can apply the soil with a brush, roller or spray gun. The spray gun gives the most smooth and professional result, allowing you to control the thickness of the layer. The brush can leave stripes, and the roller can leave the texture of the "mashing", which then have to be long grinded. The soil is applied in 2-3 thin layers with interlayer drying, the time of which is indicated on the jar by the manufacturer.
Once dry, the soil often requires grinding, and if you're planning on getting a glossy, mirrored surface, the soil is grinded with a P400-P600 abrasive, "wet," which removes dust and small bumps, and if you're looking at the maximum thickness of the corrosion layer, rather than the perfect gloss, you can just use a light P320.
| Type of surface type | Recommended soil | Number of layers | Drying time (20°C) |
|---|---|---|---|
| Pure aluminum | Epoxy two-component | 2 layers | 4-6 hours |
| Steel (casecasecase) | Soil with zinc (Galvanic) | 2-3 layers | 2-4 hours |
| Plastics and casings | Adhesive primer | 1 layer | 30 minutes. |
| Rusty areas | Converter + Epoxide | 1+2 layers | 12:24 hours. |
⚠️ Warning: Epoxy soils are sensitive to humidity when applied. Do not paint the motor in rainy weather or in an unheated garage with condensate on the walls.
Technology of applying the finish enamel
The final step is to apply a protective layer, and it's important to keep the temperature and clean in the room, and the dust is the painter's main enemy, and before you start, you have to moisten the room to nail the dust, and the engine itself is wiped with an antistatic wipe, and the paint is applied in 2-3 layers, and the first layer is made thin, almost foggy, so that there are no leaks.
Between the layers, you need to pause for solvent evaporation (Flash-off time). If you paint the second layer too early, the solvent will remain in the film, causing clouding or swelling. If you hold the interval beyond the "overlap windows", you may need interlayer grinding for adhesion.
To get the effect of "metallic" or "pearl" technology is different: first apply the base color, then a layer of varnish. Lacquer also has to be resistant to UV radiation and mechanical damage. In the case of monochromatic colors (black, white, blue) lacquer is often not required, if the enamel itself has sufficient gloss.
Drying of the finished product is a process that cannot be accelerated artificially (with a hair dryer or heat gun) to dry completely. Dry heating can lead to boiling of the solvent inside the layer and formation of bubbles. It is better to allow the motor to dry naturally in a warm, dry place for 24-48 hours.
Building and Care for New Coverage
Once the paint has been fully polymerized (final strength is gained in 7-14 days), you can start the assembly. Install candles, sensors, nameplates and casings carefully, trying not to scratch the fresh layer with fasteners. Bolts and nuts are better to use new or thoroughly cleaned of rust, so as not to spoil the appearance of the freshly painted motor.
The first outlet should be neat. Try to avoid contact with rocky bottom and algae in the first weeks until the coating is as hard as possible. Rinse the engine regularly with fresh water after each outlet into salt water, flushing the salt plaque.
Use car polishes and body waxes to care for the coating, create an additional hydrophobic layer, make it easier to clean dirt, and protect the color from burnout. Regular care will extend the life of your work for many seasons.
The secret of the perfect gloss
Between the second and third layer of paint (or in front of the varnish), you can gently traverse the surface with abrasive P1500-P2000, which removes fine dust and pellet, making the finish perfectly smooth.
Remember that even the best paint can't save the engine if you ignore the mechanical damage. Any chip to the metal should be immediately tinted with a pencil or brush to prevent the corrosion process from starting.
Can I paint the engine with ordinary car paint?
Technically possible, but the life of such a coating will be much shorter. Car paints are not always designed for constant immersion in water and exposure to salts. It is better to use specialized sea enamel or at least heat-resistant paints for calipers / discs.
Do I need to take down lower unit for painting?
Complete dismantling of the lower unit (bottom) is required only in case of deep corrosion or engine flipping. For cosmetic painting, it is enough to remove the casings, candles, sensors and carefully seal the holes.
How long does the paint on the outboard motor dry?
The drying time "on the stick" is 1-2 hours, but full polymerization and readiness for operation in water occurs in 24-48 hours at a temperature of +20 ° C. Cold weather increases this time.
How to degrease the surface before painting?
It is best to use a special degreasing (antisilicone) and gasoline or solvent 646 will also work, but they can leave a greasy film if they are not removed in time.
What to do if the paint starts to bubble?
Bubbles mean bad adhesion or moisture/oil under the layer, so you have to grind it all down to metal, re-surface it, repaint it, and local paint doesn't help.