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Frequently asked questions

Company FAQ

Technical FAQ

Company FAQ

What does “Koyo” mean?


Koyo is a Japanese company established in July of 1956 first as Ejiri Radiator in Nagoya, Japan (Aichi Prefecture) as a radiator repair shop.  Twelve years later in 1968, Ejiri Radiator established a radiator and oil cooler factory in Nagoya.  We then separated our production facilities from our repair facilities and began manufacturing radiators.  Two years later in 1970, Ejiri Radiator was renamed to Koyo Radiator Manufacturing and began expanding to branches all over Japan.   The name "Ko-yo" was created by our company's president as part of his family name Ejiri, along with his long term goals for this company.  In Japanese, "Koyo" literally translates to English as “A river expanding and flowing into the ocean.”  The first of two Kanji characters in "Ejiri" can also be pronounced as "ko" meaning "river."  Mr Ejiri signified a "river" with our company's start as a small radiator repair shop in Nagoya.  The "ocean" is the world where our company will grow and expand into.  Today Koyo Radiator Co. Ltd.  has 12 locations internationally.  We have dedicated over 53 years to manufacturing the highest quality products and leads the industry in the manufacturing of automotive (OE aftermarket and all aluminum racing), motorcycle, and agricultural radiators.


Why should I choose Koyorad for my high performance vehicle?

Koyorad is not a fly-by-night radiator company.  Unlike many of our recent competitors, Koyorad offers a 57 year history in the Heat Exchange industry with superior build quality, manufactured in our privately owned factories.

Koyorad radiators are renowned for our quality, performance, fit-and-finish and have earned this reputation through our company’s strict quality control measures.  Performance enthusiasts recognize Koyorad for our all aluminum performance radiators, but most are not aware of Koyo’s extensive background as a leading manufacturer of OE Aftermarket replacement radiators; first in Japan, now for the US, Asia and Europe domestic markets.  Aside from the sport compact performance market, ask anyone in the automotive repair or collision business here in the US, and they will tell you that Koyo OE replacement plastic/aluminum radiators lead the industry in build quality and application coverage.  We manufacture both Koyo OE Aftermarket plastic/aluminum and Koyorad All Aluminum Racing Radiators to the stringent requirements by the OE’s, matching or exceeding them, holding Koyo to a much higher standard than our racing radiator competitors.   A Koyorad All Aluminum Racing radiator is the obvious choice for your high performance vehicle.

Where are Koyorad all aluminum race radiators manufactured?

Each Koyorad All Aluminum Racing Radiator is manufactured by hand in Koyo's privately owned ISO-9001 compliant factory in Indonesia.  Koyo Japan offices first render the CAD diagrams for each racing radiator.  Next, several designs are sent to Indonesia for manufacturing.  Depending on the application, once the sample radiators are completed, product R&D is either conducted by Japan or with the  US, Japan and Singapore offices.  Once all R&D has been completed and a final design is determined, those CAD diagrams are sent and individual hand production begins.   Koyorad Racing Radiators are leak tested a total of three times during different stages of the production process.  All  tube, fin, header/side plate assembly, welding and high buff polishing is completed before a final visual inspection takes place.  Our attention to detail extends further to our rigid boxes, inlet/outlet/corner protection, and vacuum packaging assuring Koyorad product arrives safely to the end user.

I heard that Koyorad All Aluminum Racing radiators are made by XXX company and are the same company as XXX, made in China.   Is this true?

This is absolutely false and untrue.  As stated above, each Koyorad All Aluminum Racing Radiator is made in our privately owned ISO-9001 compliant factory in Indonesia.  Our Koyo | Koyorad All Aluminum Racing radiators have never been made in China, or by any other manufacturer other than Koyo.  Unlike some recent competitors, Koyorad has never shared factories with another radiator company or supplier.   Curious?  We urge you to visually compare a Koyorad All Aluminum Racing radiator with our competitors.  Koyorad header and side plates, tubes, fins, welds, accessories (drain plugs, adapters, etc.), all have superior build quality, always epoxy free and are unique to Koyorad.  You will notice that many of our competitor's products appear very similar to each other, sometimes with the only difference being a different name plate and brand embossed top plate.   Koyorad private factories have never rivetted our name plates to our side panels.  Koyorad also takes extra measures to ensure the safe arrival of your product.  Remember, our methods have been tested and proven from our experience as an OE Aftermarket replacement radiator supplier.  We do not use cheap cardboard and/or bubble wrap as some of our competitors do.   Koyorad boxes are extra rigid and have strategically placed corrugated material around inlets and outlets for protection.   Each radiator is then vacuum sealed for protection from the elements.  Our ability to offer high quality radiators with unique features and safe packaging are just a few benefits of private ownership of our factories.

How is Koyorad able to deliver such a high quality radiator?

Koyorad conducts Koyo Training Exchange programs between our Japanese and Indonesian plants from 3 months to a year in the study of Japanese workmanship. This mandatory program was developed by Koyo and implemented on the first opening of Koyo's Indonesian factory.   This program ensures the delivery of exceptional Japanese quality products to the end user.

Koyorad actually owns its factories?  How does this benefit me?

Koyorad users benefit by having the confidence and peace of mind that their engine and cooling system is in good hands.  Koyo privately owns the Indonesian factory where our All Aluminum Racing radiators are manufactured and have NEVER outsourced Koyorad radiators to any other factory.   This is truly the only way that Koyo Japan can react quickly to market changes and most importantly oversee each stage of production.  From the selection of raw materials, hand assembling tubes and fins, TIG welding, spraying the core centers with our famous blue and red KOYORAD logo, to the final vacuum packing and boxing procedures, Koyorad oversees each level of our manufactuing.


I've had my Koyo All Aluminum Racing radiator for years, and it is embossed with the “Koyo” logo and not the newer “KOYORAD” logo, what is the difference?

Our build location, quality, materials, and R&D from our racing radiators marked “Koyo” versus “KOYORAD” have not changed at all.  The logo change was in celebration of our 50th Anniversary in April 2006.  We changed and simplified our company name in Japan from Koyo Radiator Manufacturing, Co., Ltd. to Koyo Radiator Co., Ltd.  At this time, our corporate and racing logos were newly redesigned accordingly. 



Technical FAQ

Will Koyorad Radiators fit my vehicle application?

Koyo All Aluminum radiators are application specific for an easy install and will bolt directly to your factory OEM fan shrouds/fans.  Please see our Products section to see if we offer one for your vehicle.  Note:  There are a small amount of vehicle specific applications that may require some modification or even fabrication to make fit correctly.  This is sometimes contributed to slight changes in a car maker's production/parts and especially in conjunction with other aftermarket modifications.

You currently do not offer an all aluminum race radiator for my car; will you make a one-off custom radiator for my unique application?

Unfortunately we do not build one-off radiators at this time, but we are always expanding our race product line, please email your request to: info@koyoradracing.com.

Are Koyorad race radiators for Manual Transmissions only?

Yes.  Though many newer vehicles are equipped with external automatic transmission coolers, unless specified, all Koyo race radiators are designed for manual transmission vehicles. If you would like to use our race radiator in your automatic transmission vehicle, you will need to install an external transmission cooler.  If your automatic transmission vehicle is already equipped with an external transmission cooler, and you will be using a Koyorad racing radiator, we suggest an upgrade from a reputable source.

Some of your competitors recommend the use of their aftermarket shrouds, slim fan kits, and low temp “racing” thermostats, silicone hoses and fan switches, what does Koyo suggest?

Koyo recommends the use of the stock, factory equipped fan, fan shroud, thermostat, and fan switch.   For proper baseline performance testing, our engineers test and develop each Koyo radiator with the stock OE fans, shrouds, thermostat, and fan switch
for a perfect fit and optimum heat transfer.   If you plan on upgrading these accessories to use in addition to a Koyorad all alumunum radiator be sure to use high quality parts.  Saving a few dollars on cooling accesories of substandard quality may cause serious engine damage.  Consider this article written by Eric Hsu of Cosworth USA and the staff over at MotoIQ.   For the safety of your engine and cooling system be certain to source parts from a reputable manufacturer.  Koyorad recognizes that car manufacturers take great care to design their fans to draw air through radiators at an ideal rate of speed with stock fan switches and thermostats to regulate coolant and air flow.  The last thing you would want to do is downgrade your engines cooling system with sub-standard cooling accessories.  Unless from a reputable source and/or carefully tuned with data-logging software for specific race conditions, we have NOT found a better combination of cooling performance and reliability from other than the factory equipped cooling accessories.

What type of coolant or antifreeze does Koyorad recommend?

High quality antifreeze and coolant protects your engine by lowering water’s freezing point and raising water’s boiling point.  Antifreeze and coolant provides anti-corrosion properties for the metals in your radiator and cooling passages within your vehicles engine.  It also provides proper lubrication for the water pump.
It is important that the proper coolant is used for your Koyo All Aluminum Racing Radiator.  We highly recommend the use of the coolant grade listed in your vehicle’s owner's manual.
When a new Koyo radiator is installed, we recommend a complete cooling system flush and fill with new coolant. Neglecting a full cooling system flush or using the wrong coolant may result in corrosion, tube blockage, leaks, and premature wear and tear, not to mention other stresses on your engines cooling system.

Does Koyorad offer a high quality radiator cap for my Koyorad All Aluminum Racing Radiator?

Yes. Available separately, Koyorad offers a high quality 1.3 bar Hyper Cap that is made in Japan.  We only suggest the use of high quality pressure caps from a reputable manufacturer for optimum radiator performance.

Are brand new drain plugs available for my Koyorad All Aluminum Racing Radiator?  Where can I purchase one?

Yes.  Brand new Koyorad drain plugs (Koyo part# PI1186) can be purchased through the Koyorad retailer who sells Koyorad Race Radiators.  For reference, our Koyorad drain plugs are sized M10 x P1.25.

Do Koyorad All Aluminum Racing Radiators feature billet filler necks?

Yes, when applicable (not every car manufacturer has a filler neck on their radiator) only precision machined billet filler necks are TIG welded on each Koyo radiator for strength, durability and better sealing.

Does Koyorad currently offer intercoolers for the Japan market only?

Yes.  Unfortunately at this time, intercoolers are available for our Japanese market customers only.  The official North American release of Koyorad intercoolers are TBA.

Why do experienced fabricators demand using Koyorad Racing Radiators for custom “V” mount radiator/intercooler set ups?

Due to the overall cost and time associated with custom aluminum welding, experienced fabricators chose Koyorad.  We use high quality 3003 Industrial grade aluminum for our end tanks.  It is more pure, less prone to burn-through and with significantly less contaminants than cheap radiator competitors introduced to the market recently.  With the increased time spent when having to work with cheap, low quality  aluminum radiators, experienced fabricators may actually charge a customer more than working with a high quality radiator to begin with.

Post Installation Procedures

Immediately after the professional installation of your Koyo Radiator confirm with the shop attendant that:
Inspection for radiator hose or radiator core/tank leaks has been completed
2. Air pockets have been relieved from the cooling system
3. Factory fan(s) and fan shroud(s) have been reinstalled, plugged in and tested to be operating
Your cooling system was flushed and replaced with new and factory recommended coolant (If a Stop Leak type product was used previously, this must be completely flushed)