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Tru-cool 40k Transmission Cooler Silverado

When we upgraded from our 80 Series Land Cruiser to an Isuzu Dmax, one of the requirements was it had to be an automatic. Being our first automatic 4WD, there was some learning to be had, and we fitted an aftermarket transmission cooler not too long ago to cope with the extra heat. This was all part of caring for an automatic transmission.

Having owned the Dmax now for 3 years, I can tell you I’d never go back to a manual anyway, as they are so much nicer to drive around town, touring and off road.

However, automatic transmissions are a complicated, and expensive beast, and you need to take good care of them or be prepared for an expensive bill when it fails. They can be super reliable if you look after them, or a pain in the backside, both financially and in terms of inconvenience if you don’t.

Monitoring the temperatures

One of the first mods to our Dmax was an Ultra Gauge, which is a permanently mounted screen on our dashboard that reads through the OBD2 port, and displays what the vehicle is doing. The main reason for getting this was to monitor the automatic transmission temperature, as a 4WD that is loaded up with bigger tyres and towing can generate some serious transmission heat.

I’ve had this on since the vehicle was bog stock, and right through the build, towing our soft floor camper trailer and now the Reconn R2 Hybrid. There is an obvious correlation between weight and work, in that the more weight you add, and harder you make it work the temperatures climb. Excess heat is very bad for a transmission.

Our Dmax tows the Reconn R2 around when we are travelling

Initially it was hard to get the temperatures above 90 degrees, but on our 3 months up north loaded up, and towing a 1.5 tonne soft floor camper trailer in high ambient temperatures (30 – 42 degrees every day) and sitting at 100 km/h, the temperature constantly sat between 95 and 102 degrees.

I knew that with a bit of off road work thrown in, or soft beach work, without an external automatic transmission cooler we’d have a fairly significant problem. If you are considering a transmission cooler, get yourself a decent OBD2 reader (Ultra Gauge, Scan Gauge etc) and watch what the temperatures do. This is entirely dependent on how you use your vehicle, and how it is set up; not everyone will need a cooler.

Nothing beats real time monitoring with an OBD2 reader

Fitting the transmission cooler

After getting back from our 3 month trip, the Dmax had done 40k, and according to Isuzu’s specs it was due for an oil change in the transmission when towing. I was happy to roll with this, and I got one of the dealerships to do the oil change, and to fit a Davies Craig 678/698 cooler.

The core size is 213mm tall, and 281mm wide with 21 plates, running a 3/8″ inlet and is good for 13934 BTU an hour. The actual transmission coolers are not expensive at all, and you can buy kits designed for vehicles from PWR, HPD, Davies Craig and several other manufacturers.

Given my time poor situation, I opted for the dealer to install it, with the added benefit of knowing that if anything went wrong I could comfortably take it back in and get it sorted. These are basically just a small radiator, which gives the fluid more surface area to cool, before returning to the transmission.

The Davies Craig external transmission cooler in our Dmax

How to plumb the transmission cooler up

When an aftermarket transmission cooler is installed, you can plumb it a number of ways. Before we go into this though, the large majority of 4WD’s are setup so the transmission fluid comes out of the transmission and heads to the radiator, where it is cooled at the bottom, in a separate compartment before going back to the transmission. Some have external coolers, but many do not.

Tru Cool 40k Transmission Cooler

So, how can you plumb an external transmission cooler up?

Blank the OEM cooler off

Some people choose to blank the OEM (original equipment manufacturer) cooler off completely, and just run it through the aftermarket unit. This means that the oil comes out of the transmission, runs through the new cooler, and then returns to the transmission.

It also means that nothing is warming the transmission fluid up (except the transmission itself), as the coolant flowing through the radiator isn’t transferring heat across.

Before the OEM cooler

The next option is to plumb the cooler prior to the original installation. The hot oil comes out of the transmission, runs through the external cooler and then through the OEM one, before returning to the transmission. This allows the fluid to be warmed up by the radiator, and still maintains some manufacturer control over the fluid temperatures.

In this setup, the transmission cooler takes a huge load off the radiator (and your engine cooling system) as by the time it arrives its cooled significantly.

After the OEM cooler

The last way of plumbing your aftermarket cooler is to do it after the factory cooling arrangement. That is, the fluid comes out of the transmission, runs through the factory cooler, and then through the aftermarket one, and then back to the transmission.

Download surfshark mac. This way guarantees the fluid is as cool as possible prior to going back into the automatic transmission, but it makes the engines cooling system work harder as the hot fluid hits it first. That said, it still removes some of the stress, as the oil runs cooler overall, which means your engines cooling system has to do less work than without it.

Each way has its own pro’s and con’s, and you should think carefully about the best way for your situation.

Fan cooled options

Davies Craig sell a few kits, and some come with a small electric fan that draws air through. This helps in areas where it doesn’t get much air flow, or if you just want to increase the flow. Some people hook them up to temperature transducers, so when the fluid temperature hits 90 degrees or the fan comes on, and it doesn’t run any other time.

Under most circumstances you don’t need a fan, but they are a pretty good secondary option for when things really get cooking.

How’s our Dmax transmission cooler set up?

Our fluid goes through the aftermarket cooler first, then the radiator, and then back to the transmission. This helps it warm up quicker, and takes a load off the cooling system. If we were getting seriously hot temperatures, I’d consider having it the other way around, so it maximises the cooling potential, but for now its just fine.

Hill climbs work the automatic transmission very hard

What’s the end result?

Obviously, the main goal is to reduce the transmission temperatures, and the cooler has done a great job. We’d comfortably see 105 degrees towing the R2 on the bitumen at 100km/h when the ambient temperature was warm, and now its very rarely over 92. I’ve actually never had it over 100 since fitting the cooler, and it would often hit that when off road (particularly in high range) without it.

The coolant temperature is down considerably too, especially when working hard. I’d regularly hit 97 degrees, at which point the viscous hub would kick in like a mad man and bring the temperatures down, but it rarely gets near this now.

Is it worth fitting a transmission cooler?

A cooler temperature is better for the transmission, and lengthens the life of the fluid, which is a good thing. These are a very cheap investment, and like a Catch Can and secondary fuel filter, they are well worth fitting if you are working your vehicle hard.

Whether you need one or not is dependent on how hard you push your vehicle. Start with an OBD2 reader, and go from there.

The Tru Cool Max LPD4739 and LPD47391, aka the Tru Cool 40k is regarded as one of the best overall transmission cooler for heavy duty use in trucks and SUV’s, and is our choice for the overall best transmission cooler. The Tru Cool 40k gets its name from having a GVW (gross vehicle weight) rating of 40,000.

It is very common for drivers who monitor trans temps to see a significant decrease in fluid temperatures after installing this cooler. The combination of it being an efficient plate and fin style cooler and its overall size help keep transmission fluid cool in even the most extreme conditions.

Tru Cool 40k With Thermal Bypass

There are two different part numbers for the Tru Cool Max, LPD4739 and LPD47391. The two are designed exactly the same but the LPD4739 utilizes a thermal bypass system within the cooler. This lets the fluid heat up before it flows throughout the whole cooler. As fluid warms up it gets thinner, so the colder fluid only flows through the first part of the cooler until it is able to flow better after reaching optimal temperature.

The 40k cooler with thermal bypass is best for drivers who live in colder climates. It is recommended to utilize the stock transmission cooler in the radiator with the LPD4739 to allow the fluid to get to a suitable temperature. While having transmission fluid not get too warm is the goal, it still needs to get warm enough to flow properly through the body of the cooler.

Tru Cool 40k Specs

The Tru Cool 40k features a highly durable double brazen aluminum construction with precise fin spacing to ensure efficient airflow through the body for maximum cooling. With its 13 rows of cooling, the cooler does a phenomenal job at keeping temperatures in check.

It uses 3/8″ inverted hex flare fitting, which allows for the use of 6 or 8 an lines and fittings for a more secure fit and greater fluid capacity.

Because this cooler is so large and provides extremely efficient cooling capabilities, you can use this as a standalone trans cooler if you so choose.

Cooler Dimensions: 8 1/2″ x 22″ x 1 1/4″ Microsoft teams remote desktop support.

GVW: 40,000 pounds

BTU Rating: 45,000

40k Transmission Cooler

Fitting Size: 3/8″ inverted flare hex with 5/8″ thread size – This is great for those looking to install custom transmission lines

Installation Kit: Yes – Includes universal installation kit with rubber transmission line, various fittings, clamps, and mounting hardware

Recommended Uses

• Towing
• Daily Driven Trucks & SUV’s
• Performance Trucks & SUV’s

Common Applications

With how big the Tru Cool 40k is, this cooler would be the ultimate trans cooler for those drivers who demand high cooling efficiency. Many diesel truck owners who tow utilize this cooler to help better control fluid temps. The Tru Cool 40k was on our list of transmission coolers to consider in our towing guide based on its size and how much cooling capacity is offers.

Another common market you will find these coolers used is is within the performance truck realm, especially the Chevy Trailblazer SS, Jeep Cherokee SRT 8, Ford Lightning, or modded full size trucks.

In addition, the Tru Cool 40k is a perfect transmission cooler upgrade for the Cummins, Duramax, and Powerstroke diesel guys as well. Often these trucks see some serious abuse, so this trans cooler is a very viable option for those needing above average transmission cooling.

Since the Tru Cool 40k is such a popular GMC Sierra and Chevy Silverado transmission cooler upgrade on trucks that have 4l60e, 4l80e, or newer 6l80e transmissions, GM full size 1500 and 2500 pickup and SUV owners are fortunate enough to be able to easily mount and install this cooler on their trucks. There are a number of specific Tru Cool 40k Silverado brackets,install, and mounting kits available.

With how great this cooler is when it comes to keeping temperatures in a safe range, it’s easy to understand why this is the go to transmission cooler for a number of truck or SUV needs. The Tru Cool 40k is by far on of the best transmission coolers for drivers who demand excellent cooling performance.

Tru Cool 40k Install

When installing a transmission cooler, especially the Tru Cool Max 40k, it is important to figure out how much space you have to mount it. Based on its size, the most common area to install the 40k is in front of the radiator. This will provide the most air flow while driving, which will keep temps low.

40k Gvw Transmission Cooler

Most trucks and SUVs have supports that hold the hood latch or stock trans cooler in place. This would be the perfect place to mount the cooler. Since it is much larger than any stock external cooler, you will have to get creative with how you mount the Tru Cool 40k. More often than not, you can get the cooler to fit in this space with some extra mounting hardware.

When considering this cooler as a stand alone (bypassing the stock cooler), it is adequate enough to handle the needs of most applications. While is it typically recommended to utilize this cooler with the stock radiator cooler, it can certainly be used by itself.

Tru Cool 40k Mounting

There is often debate about installing the Tru Cool 40k and mounting direction. Many will argue that it should be installed either up or down. Based on past experience, we have never seen any issues with the Tru Cool 40k being mounted down (fittings down).

Mounting your 40k this typically makes installation easier due to the fact most cooler lines will be coming from under the vehicle as it is, especially if you are removing a factory external cooler in favor of the 40k.

What We Like About the Tru Cool 40k

40k Trans Cooler Silverado

• GVW Rating of 40,000
• Includes cold weather bypass – Perfect for towing in colder climates
• Fitting type – The inverted flex flare provides a more secure connection to to transmission cooler lines assuming the right fittings are used
• Can bypass the stock cooler – This cooler is large enough to use as a stand alone transmission cooler
• Includes universal installation kit for simple installs. Kit comes with transmission line, fittings, clamps, mounting hardware

Tru Cool 40k Pros & Cons

• 40,000 GVW Rating
• Includes Thermal Bypass (If Needed)
• Low Pressure Drop System
• Inverted Flare Fittings
• Ability To Use As Stand Alone Cooler
• Includes Universal Install Kit

• May Be Hard To Fit In Some Vehicles

Conclusion

Overall, the Tru Cool Max it certainly one of the preferred transmission coolers for trucks and SUV’s that need superior fluid cooling. Between its size and 40,000 GVW rating, this cooler is certainly capable of handling almost every task.

Another great benefit of the Tru Cool Max 40k is that it comes with a complete installation kit which includes extra transmission hose, clamps, and mounting hardware. While the kit comes with various fittings, it might be necessary to purchase additional fittings.

For the truck or SUV driver who demands the best, this cooler definitely fits the bill!

40k Transmission Cooler Summit