The Garage - Transmission Cooler
Installing the Tru-Cool 4590 Transmission Cooler!

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Last Updated: 12/12/2013
Transmission Cooler

Dana-Long is still listed as Long Manufacturing, LTD. although Dana now owns it.

Long Manufacturing Ltd.
6635 Ordan Drive
Mississauga, Ontario
L5T 1K6
Tel: (905) 564-7015
Fax: (905) 564-7594
Click here to visit their website or here for info regarding Tru-Cool.

Summit Racing Equipment
Address: P.O. Box 909
Akron, OH 44398-6177
Phone: 800-230-3030
Fax: 330-630-5333
The Order Line is open 24 hours
a day, 7 days a week.
Click here to visit their website.

Various Others:
AutoValue, ,the local ACE Hardware store, and ebay.

The fabrication, modifications and designs you see on this web site are completed by myself. If you duplicate these modifications you do so at your own risk. I do not endorse or make any claims to their safety, performance, On-road or off-road worthiness. Any "Product Reviews" are my sole and personal opinion. These reviews are on items purchased from or provided by reputable aftermarket suppliers. All registered trademarks belong to their respective owners.

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For quite some time I wanted to install a Transmission cooler to deal with the added stress and heat caused by towing. When an automatic transmission’s temperature exceeds 200F, the transmission fluid is pushed to its limits. Overheated transmission fluid will break down causing seals to crack, moving parts to clash, and leaks. Each year, hundreds of thousands of automatic transmissions fail and the majority of them are due to overheating of the fluid. The addition of an auxiliary transmission fluid cooler isn't just necessary to tow trailers though, it also helps when I carry extra passengers or cargo (i.e. – vacation), drive in stop-and-go traffic, drive in hot or very cold weather, or climb steep inclines.

After lots of research, my choice is the Tru-Cool 4590 Transmission Cooler. It offers Low Pressure Drop technology and has 48 Cooling Plates. The size of 11" x 11" x 1 1/2" and it's design give it a 28,000 lbs. GVW Rating!

The kit I purchased includes: Tru-Cool 4590 Transmission Cooler, 4' hose, assorted fittings and hardware, 2 styles of mounting hardware, Quick connect nylon straps & steel mounting, installation instructions.
Manufacturer Dana-Long
Manufacturer Part # TRU-COOL 4590
GVW Rating 28,000 lbs.
Product Name Transmission Cooler
Color Black
Application / Usage SUV, Truck & Heavy Towing
Connection 11/32" Hose Barb
Dimensions 11" x 11" x 1 1/2"
Low Pressure Yes
Installation For use with 5/16" & 3/8" transmission cooler lines.
Do not use on 1/2" or larger lines used on some Chrysler diesels and Allison transmissions.

This is how Low Pressure Drop technology works::
When Automatic Transmission Fluid (ATF) is cold it is viscous. The unique Tru-Cool design allows the colder, thicker ATF to flow more efficiently through two open bypass channels positioned at the top of the cooler. As operating temperatures increase, the ATF becomes hotter and thinner, It's then directed through the core where it is cooled. Tru-Cool's highly efficient cooling technology combines improved protection against lube failure with optimal heat transfer.

Long Tru-Cool Oil Coolers offer advanced cooling protection for many towing applications. The advanced technology out performs TUBE & FIN Designs, Delivers up to 15 times less flow restrictions, 30% more cooling delivers maximum heat transfer, Self-Regulating for maximum lube flow protection through start-up, varied temperatures and driving conditions, heavy loads and towing.

I want to install the Tru-Cool transmission fluid cooler in front of all other heat exchangers (i.e. – radiator, A/C condenser). It will have good incoming airflow and this is the only location where I will get the full 100% cooling efficiency. For every 20F degree drop in transmission fluid temperature, I can expect to extend the fluid and equipment life, thereby extending the life of my Durango. That's why it is very important to have a quality transmission cooler, and more importantly, to have it correctly installed.

There is nothing wrong with omitting the OEM cooler altogether considering the size and rating of this Tru-Cool cooler, but I live in cold climate and prefer to have my transmission in ideal operating temperature and this is why I will connect the Tru-Cool transmission cooler in-line after the OEM cooler (within the radiator). The fluid will pass through the OEM cooler first and then through the Tru-Cool transmission cooler second before returning into the transmission.

What's involved to get this job done?
Although the kit comes with everything needed to install this cooler I am going to fabricate a heavy duty bracket which will bolt to the mounting points of the OEM A/C auxiliary fan which I had removed when I did the fan delete project.
Thus, I will fabricate a bracket from steel which I have on hand to mount it in front of the A/C Condenser. This is really a simple install and I am not touching the supply line at all.

Shopping List
Part Description
Long Tru-Cool 4590 transmission cooler
This cooler is rated at 28,000 GVW and measures 11"x11"x1.5". Designed for Heavy duty applications, from towing to racing. All parts are included to mount and plumb this cooler. This cooler comes with a manufacturers limited lifetime warranty.

(1) $97.99 each w/FREE Shipping @ OPT (Oregon Performance Transmissions)
Parts Master Automatic Transmission Fluid ATF+4®
Designed to meet the specific requirements of Chrysler, Dodge & Jeep vehicles. Parts Master ATF+4® is a high-quality synthetic transmission fluid specifically engineered to protect and prolong the life of Chrysler automatic transmissions, excellent low and high temperature performance, superior anti-wear and anti-oxidation properties, and contains additive to reduce foaming.

(2) $4.39 each + tax @ Auto Value

Cost: I also used material from my metal supply stash but didn't add it to the cost. The entire cost for this project at this point comes out to approx. $110.00.

The basic procedure of this project is to fabricate a steel bracket to mount the Long Tru-Cool 4590 transmission cooler and mount it to the front of the A/C condenser

Let's get started:
The begin by fabricating and weld up a bracket for the transmission cooler from steel. I gave the bracket a coat of paint and mounted the new cooler to the front of the A/C condenser utilizing the brackets which held the no longer existing auxiliary A/C fan (see Fan Delete mod) in place.

Fuel & Transmission Line Disconnect Tool Kits are available at Summit Racing and most local Car Parts Stores.

Fabricating and installing the bracket was overall a fairly simple task but it did involve some time to get the bends and angles right.

Both of the barbs of my new transmission cooler pointing now to the passenger side which is the same side the OEM transmission cooler lines have their connections located.
1. Left side of custom bracket 2. Right side of custom bracket 3. Front view of custom bracket

I then remove the passenger side rubber skirt which is held with push clips to gain access to the return line which enters in the top of the radiator. I also unbolt the fan shroud/reservoir on the passenger side and loosen the bolt on the driver side to move the entire piece towards the engine to gain even better access.

I then disconnect the return line (see Fig.1 for 03 Durango 5.9l) from the transmission line using a disconnect tool and unbolt and remove the return line from the top of the radiator. There is a small screw on the bottom which holds the steel line in place, I remove this one too.
4. I am moving the OEM shroud back for better access to the cooling line connection. 5. This is the connection of the return line on top of the radiator besides the radiator hose.

I then take the line out and cut it the top section after the first bend so that I can route the line around the radiator but have enough of line left for the tubing to slip about 2" over.
I deburr all line cuts inside and out and use air pressure to clear the line of any debris. I also use a scotch pad to clean the outside of the line before slipping the hoses over it and securing it with one of the hose clamps provided in the kit.

6. Reconnected the fitting with a hose secured to the line via hose clamps.

I repeat the same for the lower end of the hard line and make sure to leave the quick connect section alone.
There is no need to flare the hard lines.

Now all what is left is to cut the hose ends to the proper length and connect them to the transmission cooler. I fill the transmission fluid up with one quart, (a half quart was approximately the amount I lost while disconnecting lines etc., and I added another half of a quart to make up for the new transmission cooler. I then bolted the fan shroud back into it's place, ran the engine in neutral and added a bit of additional transmission fluid as needed. The test run was successful, no leaks.

I was closing the hood to test if there are any issues with the new cooler upfront and sure enough the front part of my plastic grille scraped on the new transmission cooler.

It was just about a half inch shy of letting the cooler pass. I used my trusty Dremel with a cut-off wheel to enlarge the already existing cut-out in the lower edge of the grille. That took all but 5 minutes for a perfect fit.

TIP: When checking transmission fluid park vehicle on level surface, engage parking brake and start engine. Leave car in neutral or park, pull the dip stick for the transmission fluid and check it. If it is below the OK indication on the dip stick keep adding small amounts of fluid into the dip stick tube via funnel until it is.
Have a clean disposable shop towel handy to wipe over the dip stick before re-inserting it. Always use the recommended transmission fluid and make sure to clean the funnel for the dip stick tube before you get started.
Transmission Funnel are available at most local Car Parts Stores and only costs a few bucks.)It's a good investment.)
7. The completed connection from the return line of the radiator to the auxiliary cooler.

9. Attaching a transmission hose to the line and re-connect it to the quick connect fitting.

11. Re-installing the rubber skirt with new plastic push pins. The work is almost done.
8. Cutting the lower transmission line with the quick connect end using a tube cutter.

10. Routing the hose between the frame and the radiator and connect it to the trans cooler.

12. I had to enlarge the existing cut-out in the plastic grill to pass the transmission cooler.

Finishing up:
It didn't seem that long but the day turned to night. I was to tired to do a test ride but I started the engine up, let it run for a few minutes and checked if there are any leaks. All was good. On the next morning I took the Durango for a 10 mile test drive and all connection were solid.

This transmission cooler was a lot of fun to install but I don't recommend having a beer or two when doing it.
The are definitely more affordable coolers but this one seemed to make the most sense here in the cold as it is Self-Regulating for maximum lube flow which is a great design in cold conditions. After adding this cooler I don't see above 170 degrees in fluid temperature which is a noticable difference considering I was towing uphill. I am very happy with the result!

To sum it all up, I really expected this to be a toughy but it wasn't. I now have much better cooling for my transmission and with substantially lower fluid operating temperatures comes extended life and less chance of failures.
Yep, I'm good!

This project was completed on 12-29-2012

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