Do I Need To Install A Transmission Cooler?
There are a number of benefits to using a transmission cooler on your car, truck, or SUV. The biggest benefit to installing an auxiliary transmission oil cooler is that it will help do what its name indicates, which is cool your transmission fluid.
More often than not, most vehicles can utilize a transmission cooler to help prolong the life of their transmission. There are different types of transmission coolers, and each one comes in different shapes, sizes, and has their own benefit. Any type of transmission cooler you plan on installing will help reduce trans fluid temperatures. This keep your transmission in a safe operating range which in turn will allow your transmission to last longer.
Hayden 679 Transmission Cooler Review Summit Racing Rating: 4.8/5 Amazon Rating: 4.7/5 Shop On Amazon The Hayden Automotive 679 (1679) offers superior cooling to keep your transmission temperature in a safe range. Hayden Automotive engineers, manufactures and supplies a wide range of products designed to keep your car, truck or performance vehicle running cool. From fan clutches and electric fans to performance oil and transmission coolers, we’ve got what you need to protect your vehicle from damaging and performance robbing heat. Transmission, Engine and Power Steering Oil Coolers Hayden® Automotive engineers, manufactures and supplies a wide range of products designed to keep your car, truck or performance vehicle running cool. Hayden® oil coolers remove destructive heat generated in the transmission, engine and power steering systems to increase component life. Ultra-Cool™ Transmission Oil Cooler Kit by Hayden®. This product is an effective and economical way to keep your transmission at its optimum operating temperature. The high-efficiency turbulators in every tube direct fluid for.
Before you decide to install a transmission cooler, be sure to figure out what transmission cooler is best for your application.
Transmission Cooler Mounting Position
When figuring out how to install a transmission cooler, it is typically recommended to mount it in a location that gets a significant amount of airflow. Based on this, the best place to mount a cooler would be in front of the air conditioning condenser. This position will allow the trans cooler to get ample air flow while moving in addition to getting air from the engine’s cooling fans when stopped.
When installing a transmission cooler on the condenser, using a transmission oil cooler mounting kit will make the process easy and hassle free. The mounting kits come with heady duty plastic zip ties and rubber spacers. The spacers are used to space the cooler from the condenser to prevent direct contact between the two. You can find transmission mounting kits here.
In some applications however, it may be best to have a remote mounted transmission cooler that utilizes a fan to help cool the fluid. This is typically found in more extreme applications such as those who drag race or tow for example.
Where ever your cooler is mounted, it needs to get enough air flow to help keep the fluid cool.
Transmission Cooler Orientation
When installing automatic transmission coolers, there is often debate as to whether cooler orientation matters. More often than not, transmission cooler orientation does not make much of a difference. While some may argue that you need to install a certain type of cooler inverted to prevent air bubbles, the transmission line pressure it strong enough to push fluid through the entire cooler to prevent this.
Should I Bypass My Radiator When Installing An External Transmission Cooler?
A common question we get asked is whether it is recommended to bypass the radiator with your external transmission cooler. The easiest answer to this is, it depends. There are a number of factors that determine if you should use your trans cooler as a stand alone unit or in series with the factor radiator transmission cool.
If you live in a very warm area, it may be better to bypass the factory transmission cooler in the radiator in favor of a larger, external transmission cooler. Reason being, the radiator can act as a heater and warm the transmission fluid higher than where you may be comfortable with it operating (200 + degrees), especially if you face a lot of stop and go traffic or other harsh driving conditions.
It is recommended however to keep the factory radiator transmission cooler and use and external cooler if you live in a cooler climate. The factory cooler will help get the transmission temperature into a suitable range. When it comes to cooling your transmission, you can actually over cool it, and it may not be able to flow as well compared to warmer fluid.
Transmission Cooler Line Path & Flow Direction
When installing your new transmission cooler, it is important to figure out not only where you will mount it, but how to run the lines. In most applications where the external trans cooler is used in addition to the factory one, you will need to route the new transmission lines from the radiator to the external cooler.
The below transmission cooler installation diagram shows the transmission fluid flow direction and how the fluid will be routed through a new external cooler.
You will need to determine which line is the return for the transmission. You want the already warm fluid to flow into the external cooler to help better control fluid temperatures, so the transmission cooler flow direction will look something like this:
Transmission out (fluid hot) > radiator cooler in > radiator cooler out > external transmission cooler in > transmission cooler out > transmission in (fluid cool).
Audacity on mac catalina. If you plan to use rubber transmission hose and keep the stock cooler lines, you need to connect the cooler return line to your vehicle’s return line. In most cases you’ll need to make a cut to the factory line and connect the new rubber line to it. This can be done with a double sided barb fitting, or by flaring the metal line and then clamping the new rubber hose to it.
How Much Does It Cost To Install A Transmission Cooler?
Aside from the purchase of a transmission cooler, additional costs may come from extra parts such as transmission fluid, transmission hose, clamps, fittings, and mounting pieces. A number of transmission coolers come with installation kits that contain most of these items aside from fluid. However, it is recommended to figure out what you need before buying a complete kit. Most transmission cooler installation kits may not be 100% complete for your application, so it would be best to assess what you need and what is included.
If you were to just purchase the cooler then source the additional parts needed, there would not be much of an additional cost.
If you have a desire to run custom lines and AN fittings, then the cost will certainly increase. While installing basic rubber lines might work for most, in some cases, your vehicle may need custom lines, which are more costly than standard transmission lines.
Depending on the cooler you purchase and your lines, you can spend as little as $20 extra to install a cooler, or in some cases, as much as $150 or more. Ultimately, the cost to install an automatic transmission oil cooler is dependent on what your needs are.
Conclusion
When installing a transmission cooler in your car, truck or SUV, it is important to consider not only the cooler size, but where to mount it, and how to run the lines. Mounting a transmission cooler is typically best in front of the air conditioning condenser so it gets ample air flow. Mounting here provides significant air flow which will help keep temperatures low.
In addition, having the right parts to install a transmission makes the process easier. Many trans coolers come with installation kits that contain rubber hose, clamps, fittings, and mounting hardware. While this is great, it is best to remember that these are universal kits that may not contain exactly what you need. When you install your cooler you will need to account for adding additional transmission fluid to compensate for the increased capacity of the transmission cooling system.
An automatic transmission cooler will not only help keep your fluid temperatures lower, but improves the longevity of your transmission. For a small investment, you can save thousands in repairs needed for replacing a failed transmission due to over heating.

The Hayden Automotive 678 (1678) offers superior cooling to keep your transmission temperature in a safe range. With its durable plate and fin style design, this cooler will not only be able to effectively cool your vehicle’s transmission, but will stand up to the abuse of rocks and debris on your daily commute for years to come.

Just like all Rapid – Cool transmission coolers, the Hayden 678 comes with pre-drilled mounting holes and utilizes barb style transmission line fittings.
This helps to make installation quick and easy If you’re looking for a highly efficient easy to install, the Hayden 678 plate and fin cooler might be the cooler for you.
As featured in our best transmission coolers guide, The Hayden 678 is one of the best all around and highest rated transmission coolers available.
For the price, this cooler packs a strong punch and will certainly do the job for your average truck or SUV!
Hayden 678 | GVWR | Type Of Cooler | Price |
24,000 | Plate & Fin |
Hayden 678 Specs
The Hayden 678’s plate and fin body measures 11″ x 9 1/2″ x 3/4″ which is not only large enough to efficiently cool your transmission fluid, but is still thin enough to mount in most common locations without much hassle.
Audio realtek for mac os x. The Hayden Rapid Cool 678 offers a GVW rating of up to 24,000 pounds which provides the ability to help tow up to 5,000 pounds (if your vehicle is rated to do so).
Its 24,000 GVW rating makes it a great cooler for pickup trucks, SUVs, vans, class C mobile homes and large travel trailers up to 24 feet in length.
For the cost, the Hayden packs a mighty punch in terms of capabilities. Not only is it not too large where it can cause mounting issues, but it has the ability to help tow more than enough for more common applications.
Cooler Dimensions: 11″ x 9 1/2″ x 3/4″
GVW: 20,000 pounds
Fitting Size: 3/8″ barb
Number of Cooling Rows: 23
Hayden 678 Installation
One of the biggest benefits of the Hayden 678 or any other Rapid Cool trans cooler is that it comes as a universal kit. However, transmission cooler installation will depend on where you plan on mounting the cooler, and if this requires any extra parts.
The Hayden 678 install kit comes with extra transmission hose, mounting brackets with nuts and bolts, various barb fittings, hose clamps, spacers and mounting ties.
Since the most common spot to mount a transmission cooler is in front of the air conditioning condenser and radiator, the mounting and install parts included should be enough for most vehicles. As usual, you may require additional line and fittings.
Since this cooler utilizes barb fittings, it is best to use a traditional rubber transmission line. It is also recommended to double check the lines at the cooler over time to ensure a secure, leak free connection.
Despite its size, it is recommended to run this cooler in addition to the stock cooler in the radiator. While this may be large enough to use as a stand alone cooler, the best use would be to use this so the fluid runs through the cooler after the radiator.
Hayden 678 Pros & Cons
Pros

- Easy To Install
- 24,000 GVW Rating
- Plate & Fin Design
- Includes Complete Install Kit
Cons
- Barb Fittings
- Hard To Install In Tight Spaces
Conclusion
Between its moderately high 24,000 GVW rating, efficient plate and fin style design, and affordability, the Hayden Automotive 678 transmission cooler is by far one of the best transmission coolers available. The 24,000 GVW allows for ample trans cooling in most common applications and it’s price certainly is friendly on your wallet.
Another great benefit the Hayden 678 offers is that it comes with a complete installation kit with extra transmission hose, clamps, and everything else needed for an easy installation.
While the kit comes with various fittings, it might be necessary to purchase additional fittings, depending on how you plan to route the fluid lines.
Overall, it is hard to beat this cooler, and for the budget minded driver with above average cooling needs, the Hayden 678 certainly fits the bill. With over 350 reviews on Amazon with a 4.7 star average, most will agree that this cooler is certainly a viable option and is a great buy!
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