Transmission Cooler Recommendation for a 2005 Nissan Titan Towing a Rockwood Roo 21SS
Question:
I recently purchased a Rockwood Roo 21SS and am wondering about the advisability of installing a transmission cooler. What type to buy? How large a unit is needed? Do they come w/ a temp gage? How complicated is the installation? Are there instructions? I tow w/ a 05 Nissan Titan, King cab. Thank you
asked by: L B
Expert Reply:
Adding a transmission cooler to your 2005 Nissan Titan is a great idea to improve transmission performance and longevity, especially if you will be towing your Rockwood Roo 21SS trailer. Towing will put additional strain on an engine and transmission and one of the most common causes of transmission failure is overheating.
When choosing a transmission cooler, it is best to choose the largest cooler that will fit in the space you have available because transmission fluid cannot be over cooled. The ideal location to install a transmission cooler is either in front of an AC condenser or in front of your radiator. I recommend measuring the available space in those locations and choosing a transmission cooler that will fit.
I did some research on the towing capacity of your Titan and the size of your Rockwood Roo and, if you have the space available, I would recommend looking at the Derale Series 8000 Transmission Cooler, # D13503. This cooler measures 11 inches wide x 8-3/4 inches tall x 7/8 inch deep.
The difficulty of the installation will really depend on your mechanical experience. Transmission coolers do come with installation instructions, however, they are not vehicle specific. Some vehicles require the front bumper fascia or grille to be removed whereas others have enough room to install the cooler without having to remove other parts.
One of the more difficult parts that some people have with the installation of a transmission cooler is locating the transmission return line. One tip that I can give is to first locate the transmission lines that run from the transmission to the radiator. Next, drive your vehicle for about 5 minutes. Using caution, feel both transmission lines. The cooler line is the return line and this is the line you will tap into.
If your transmission lines are rubber hoses, you will not need any additional parts to complete the installation. If your lines are metal, then you can either cut and flare your existing lines, or use compression fittings to attach the hoses from the transmission cooler to the transmission lines. You will want to measure the diameter of your transmission lines to determine which compression fittings will work for you. If you have 5/16 inch lines, use part # D13031. If you have 3/8 inch lines, use # D13032. If you have 1/2 inch lines, use # D13033.
The transmission coolers do not include a temperature gauge, but you can add a temperature gauge using the Derale Remote Transmission Filter Kit with Temperature Gauge, # D13091. You can install this kit on the return line coming from the Derale cooler. I have attached an installation video of this kit for you to check out. You will notice that the vehicle is different from your Titan, but it should give you an idea of what is involved.
I have also attached two FAQ articles on transmission coolers and an installation video. Again, the vehicle is different from your Titan, but it should give you an idea on what is involved. It also shows how the compression fittings are installed if you need to use them.

Products Referenced in This Question
Derale Transmission Line Compression Fitting Kit - 5/16" Line to 3/8" NPT Barb
- Accessories and Parts
- Transmission Coolers
- Fittings
- 3/8 Inch NPT Hose Barb
- Derale
more information >
Derale Transmission Line Compression Fitting Kit - 3/8" Line to 3/8" NPT Barb
- Accessories and Parts
- Transmission Coolers
- Fittings
- 3/8 Inch NPT Hose Barb
- Derale
more information >
Derale Transmission Line Compression Fitting Kit - 1/2" Line to 1/2" NPT Barb
- Accessories and Parts
- Transmission Coolers
- Fittings
- 1/2 Inch NPT Hose Barb
- Derale
more information >
Derale Remote Transmission Filter Kit w/ Temperature Gauge
- Accessories and Parts
- Transmission Coolers
- Filter
- Derale
more information >
Derale Series 8000 Plate-Fin Transmission Cooler Kit w/Barb Inlets - Class III - Efficient
- Transmission Coolers
- Plate-Fin Cooler
- Mid-Size Truck
- SUV
- Van
- Standard Mount
- 11W x 8-3/4T x 7/8D Inch
- With 11/32 Inch Hose Barb Inlets
- Derale
more information >
Product Page this Question was Asked From
Derale Series 9000 Plate-Fin Transmission Cooler Kit w/ NPT Inlets - Class V - Extra Efficient
- Transmission Coolers
- Plate-Fin Cooler
- Heavy-Duty Truck
- Standard Mount
- 9-3/4W x 10-5/8T x 1-1/4D Inch
- With 1/2 Inch NPT
- Derale
more information >
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