Can You Paint a Car Radiator & Does That Make it Less Efficient
Can I Spray Paint my Radiator Black?
We get asked this question frequently regarding performance aftermarket aluminum radiators. In many cases of a classic muscle car or hot rod the stock copper/brass radiator, which came with a black finish from the factory, is replaced by a high performance two or three row aluminum radiator. While the additional cooling and capacity is a welcome addition to keeping engine temperatures in check, not everyone likes the bare aluminum finish. For some it is an “eyesore” that sticks out, especially in a stock-appearing engine bay. For others it is a maintenance issue. Not everyone has the time to keep a bare aluminum radiator finish looking good. So, giving that aluminum radiator a quick blast of any old black spray paint you have on the shelf sounds like a good solution, right? Not so fast. Let’s run through a few frequent questions first and any “gotchas” you need to be aware of to ensure success when painting your aluminum radiator black.
Can I Spray Paint My Radiator Black?
Yes, it is completely conceivable to spray paint your radiator black. This includes both traditional copper/brass radiators and modern aluminum radiators, provided the proper materials and steps are used to prevent any reduction in cooling efficiency. With the right preparation and materials, painting a radiator is safe and effective.
Is Painting a Radiator a Good Idea?
Painting a radiator can be a good idea for improving appearance and preventing corrosion. It is important to use the best automotive radiator paint. This will be a heat-resistant paint made for metal surfaces. Avoid applying too thick a layer or too many coats of paint that could reduce heat transfer.
Can You Paint an Aluminum Radiator Black?
Yes, as we mentioned above, aluminum radiators can certainly be painted as well. The surface should be cleaned, large areas like end tanks and top plates lightly sanded and coated with a high-temp stable primer before applying a high-temperature spray paint made for metals.
Paint Tips for Best Results:
- Use high-heat rated spray paint and primer (rated for 200° F or higher)
- Apply thin, even coats with just enough coverage to provide a solid black out finish
- Avoid clogging cooling fins, which can happen if you’re too close when spraying
- Paint the radiator off the vehicle and within recommended surface temperatures
How to Paint a Car Radiator
OK, so you’ve got the green light to freshen that old copper/brass radiator or “hide” your new aluminum radiator with some black paint, but hold on a sec. Let’s step back and take a breath to run through the correct steps of how to paint a car radiator, including cleaning and prepping the radiator before you grab that spray can of high-temperature black. Taking a minute here to review the proper work process of how to paint a car radiator will reward you with a higher success rate on your project, providing you with a great looking radiator finish that will last while not reducing your cooling efficiency in the process. Lastly, can you paint a radiator on a car? Sure, but removing it from the vehicle will provide the best results.
Clean the Radiator: Remove all large dirt and debris using a garden hose and/or compressed air, or even a soft brush for around mounting brackets and such. A clean surface helps the paint stick and prevents buildup that could block airflow.
Degrease the Surface: Apply a household cleaner/degreaser to remove oil and grime. This is especially important for used radiators that may have engine residue. Some cleaners can etch aluminum, so be sure to thoroughly rinse them away.
Tape Off Fittings and Connections: Cover all hose fittings, threads, caps, and any other parts that should not be painted. This keeps paint out of areas that need to stay clean for proper installation.
Consider Hot Tank Cleaning: For old or heavily used radiators, a radiator shop can provide hot tank cleaning. This service removes internal and external buildup and helps restore performance. They can also straighten any bent cooling fins as well
Apply High-Temperature Paint: Use spray primer and black paint made for high-heat metal surfaces. Apply light, even coats to avoid clogging the fins or reducing heat transfer.
Paint Application Tips:
- Shake the can before use and throughout the painting process
- Hold the can 10 to 12 inches from the surface for light coats
- Let each coat dry per the printed can’s instructions before adding another coat
- Avoid spraying directly into the fins, you only need to coat the edges of the fins
Does Painting a Car Radiator Make it Less Efficient?
Like any DIY project, if you don’t follow the proper steps and/or use the incorrect products, your results will be far from optimal. It is easy to get things wrong, rush the job, or use the wrong paint and not only will the final product look bad, but in the case of painting a radiator the paint may not stick long term, or you may apply too much product, affecting the thermal transfer ability of the radiator. So, your best bet is to approach each step carefully, follow product directions, and take your time and your radiator’s new black finish will look great, last a long time, and will not reduce the thermal efficiency of your radiator.
How Cooling Efficiency Can Be Affected:
- Thick paint can block airflow and trap heat
- Paint not made for high temperatures can peel or act as insulation
- Poor preparation can lead to flaking and reduced heat transfer
How to Avoid Problems:
- Using high-temperature radiator paint, applying light, even coats help prevent issues
- It is important not to spray directly into the fins or apply too much paint.
- Ensure the radiator is fully cleaned and prepped and completely dry before painting
- Monitor temperature and spray your paint when conditions are optimal
Skip the Paint—Buy a Black Radiator Instead
Can you paint a car radiator? Sure, but you might not have to. That’s right, if you’re currently shopping for a radiator and thinking you’re going to want to paint it black for your project needs, you may just be able to source a radiator that is already black. Speedway Motors offers a universal black radiator in multiple widths to fit popular vehicle fitments using SBC or BBC engines. These radiators feature a black epoxy painted finish for an OEM/low profile appearance in your hot rod, muscle car, or classic truck. These aluminum crossflow designs feature two rows of 1-inch tubes and single or double pass options. Widths range from 22 to 31 inches.
Of course, if you’re not running a Chevy V8 engine we still have a Ford, Mopar, and other fitment options in our line of aluminum Speedway radiators, you’ll just have to provide the black finish yourself using the steps we outlined earlier in this article. Our full selection of universal radiator and direct fit options includes fitments for pickups, T-buckets, and much more, so be sure to have a look there to see what might fit your needs. To help determine which radiator you need be sure to see our 3 row vs 4 row radiator Toolbox guide to determine the best option to keep your ride’s temperatures in check.
Keep your ride running cool while providing a low-profile black finish (or pick up a new aluminum radiator already finished with a black hi-temp coating) for those hot summer drives and keep putting the miles on!
