Hayden 678 Transmission Cooler

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 Hayden 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 678GVWRType Of CoolerPrice
Hayden 678 transmission cooler - Transmission Cooler Guide24,000Plate & FinShop Now

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. 

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

Hayden 678 Transmission Cooler Installation On Toyota Tacoma - Transmission Cooler Guide

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


  • Easy To Install
  • 24,000 GVW Rating
  • Plate & Fin Design
  • Includes Complete Install Kit


  • Barb Fittings
  • Hard To Install In Tight Spaces


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!

Get The Best Price On Hayden 678 Transmission Coolers

Hayden 678 transmission cooler - Transmission Cooler GuideLower transmission temps with the help of the Hayden 678 today. Shop Now!

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Hayden 678

With over 350 reviews, the Hayden 678 Rapid Cool is one of the top rated transmission coolers on the market. Learn what makes this cooler great!

Product Brand: Hayden

Editor's Rating:


  • Easy To Install
  • 24,000 GVW Rating
  • Plate & Fin Design
  • Includes Complete Install Kit


  • Barb Fittings
  • Hard To Install In Tight Spaces