Install complete on additional transmission cooler

Coolant temp to the cooler on the transmission is controlled by the engine thermostat since the transmission cooler lines tap into heater core lines near the firewall. Lot of expenditure of effort and money for no gain. Others have looked at adding transmission cooler to 2019. Not sure what the final verdict was there regards need, and if needed, how to accomplish. Search all posts by @blaserdude .

 

When I was in your position I pulled out my old engineering heat transfer text and found that you only need air flow equivalent to 7 mph through a liquid-to-air heat exchanger (radiators and trans coolers) to achieve the maximum cooling they are capable of. The fan won't help you unless you're mounting the cooler where it isn't exposed to the wind from driving or unless you're driving less than 7 mph.

Mount your cooler in front of your radiator and you'll get all of the airflow you need without a fan.

The stock radiator and cooling fan are more than sufficient to keep your engine cool even when a trans cooler is mounted in front of it. Mine was setup this way when I towed a trailer that weighed over 10k lbs from Seattle to Boston in my '08 Tundra with 35's and stock gears.

I used a Bluetooth dongle on the OBD-II port paired to an android tablet to display real-time trans and coolant temp throughout the entire trip.The trans temp would get higher than I wanted if I didn't monitor it carefully and allow my speed to drop in the mountains and on steep hills, but the engine coolant temp warmed to 195°F (normal target operating temp) and never budged higher under any load.

 

I'm pretty sure some of the 2nd and 3rd gens had the "hockey puck" style trans cooler, but it was only the ones without the trailer towing package.

This is a screen shot of the dealer instructions for installing a factory trans cooler on 2008 Tundras not equiped with the trailer towing package from the factory.

Step #2a and b are to remove the hockey puck style transmission oil cooler. (Liquid-to-liquid heat excahnger transfers heat from the transmission fluid to the engine coolant.)

Step #3 is to begin installing the liquid-to-air heat exchanger (traditional fin-style trans cooler)

 

in some older (for example 2016) models, There is a heat exchanger to warm-up the trans fluid. There is also a trans cooler that comes with the tow package.
Once everything is at the operating temperatures, I assume that the heat exchanger (coolant temp) will be the floor for the trans temp. Meaning that if your coolant temp is in 189°F-195°F range, your trans temp will be at a minimum somewhere in that range and not much cooler and that's what I read with my scangauge.

A co-worker removed the heat exchanger but I couldn't get the details before he left the company.
He said he wasn't going to be anywhere cold and winters in our area are very mild.
Heat exchanger is heating up the trans fluid and if you don't live in very cold places, I assume you can delete it. Not sure how much the delete will drop the temps.
also not sure what was involved in removing it or if he did it himself. The only problem is if you sell the car and the buyer moves to colder places ...

You can also argue that if trans temps are way over 195F then heat exchanger is actually cooling the trans fluid ... but I think that might fall under very rare cases. idk

Has anyone here done the heat exchanger delete or knows anything about it?

 

This was pretty much exactly what I was planning on doing. Adding a cooler after the radiator thermostate but before the heat exchanger to just give it additional cooling power. I figured this would effect the rest of the cooling system less too, and just put the cooler fluid where needed, at the transmission heat exchanger.

 

Very interested to see how this works out. I too have a 2019 and am not happy with the current setup. I am betting they put them on next years model.
bc

 

Pretty sure Toyota will not put the transmissions & their reputation in danger by removing the cooler if it was needed. Maybe the cooler was not that effective to begin with and/or the new design does not require it!

I wouldn't worry too much about.

can you guys with no cooler report your trans temperatures and we can compare ...

 

My 019 runs around 210-212 just driving the interstate (takes a while to get there). It runs upwards of 215-218 when towing my small trailer and UTV. The 08 I had would not go above 200-205 under same conditions. It heats up slower but cools down slower as well. Driving in S mode and not using cruise helps. When I need to pass on the interstate, it heats up quickly and can stay there for quite a while.
Thanks,
bc

 

your temps seems to be within the normal range based on my research!

 

On my 2018, I pinned the hockey puck, and my trans temps have dropped 30-50 degrees. Now, instead of holding at 200 and going up to 215, it holds at 150-160 and goes up to close to 170. That’s plenty warm for transmission operating temps, and there can be no reasonable argument that the lower temp does not extend fluid life—even with Toyota’s synthetic fluid.

 

I only wish I had the option to do that!
bc

 

So OP, how did you mount the cooler and what lines were used for the input and output? Did they make that same cooler with a pusher fan when you bought it?

 

How do you go about pinning the transmission open on a 2nd gen?

 

This is not on a tundra, but basically the exact same process. Look for the puck on the passenger side of the transmission.
Push plunger in slighty, push wire through hole to keep plunger depressed. Done


Pinned


Below is the Tundra plunger. It's sorta hidden inside a hex bolt.

 

Thanks!

 

https://youtu.be/Az2ItTMLy_o

 

@Krohsis, I know it has been awhile since this forum but do you remember which line you put the cooler on top or bottom in your before pic?

 

we used to PM ...

He sold the Tundra and bought a Chevy Silverado 2500HD to handle loads easier or to be able to handle bigger loads.

I doubt he'll be back unless the Chevy gives him more headache than the bigger load capability.

Btw, he was seeing the thermostat opening at 250F (with the factory cooler) and he installed additional cooler. Sometimes I wonder that's why Toyota decided to remove the trans cooler on '18 and up.... Because according to him, the cooler was not that effective or consistent to begin with!

 

@TTund16, much appreciated. I’m trying to figure out which line is the “in” and which is “return”. I would assume it would probably be best to install the cooler on the return line before it goes back to the transmission, so it will get a 2nd cool in a sense, just need to know which line is which. Not a mechanic but this project seems pretty doable.

 

Edit: @Krohsis added a secondary cooler on series with the OEM transmission fluid cooler. @Krohsis had a extremely heavy tow that was problematic with the capacity of the OEM cooler. If you already have an OEM transmission fluid cooler, you should monitor your transmission fluid temperatures first to determine if your towing actually requires a secondary cooler in series with the OEM cooler.

I don't know how @Krohsis plumbed it, but if the secondary cooler is oriented vertically with in/out on the side, the correct answer is to have the inlet flow from the transmission (or from the OEM cooler) come in at the bottom of the cooler, and outlet flow back to the transmission come out at the top of the cooler. This configuration prevents air from being trapped in the transmission fluid cooler. The cooler stays flooded and heat transfer efficiency is maximized.

If the cooler is oriented horizontally with in and out on the top that is acceptable, and it makes no difference which is in and which is out. Having the in/out on the bottom of the heat exchanger is a no-no, since air will definitely be trapped inside the heat exchanger.

If you have the 5.7L/A60, the flow directions at the thermostat connections are shown below:

 

@WVrackaholic

iirc, with his cooler, the lower one was IN and the upper one was OUT.
This also matches what @JohnLakeman is saying. However i am not 100% sure since I never added the cooler.

We used to compare numbers and talk scan gauge and he added rear diff temperature gauge and we talked about adding engine oil temp gauge ...
As I mentioned, I think his thermostat opened at 250F and mine opens at 200F so the two cars were inconsistent even though iirc we had the same year and model cars.

 

After seeing how the cooling and warming system is designed... I can't help but wonder if one is counter-acting the other ???

The puck is designed to hold trans fluid temps at engine coolant temp by piping coolant through it. In most cases this would be fine if its all that were available to cool the trans... but what if the front mounted auxillary cooler is trying to cool the fluid and the puck is trying to heat it to engine temp???

Anyone else see the conflict here ?

My best educated guess is that the puck coolant lines should be bypassed around the puck when using a front mount trans cooler to avoid adding additional heat via the engine coolant.


I'm surprised nobody else has considered this.

 

Since I've read somewhere that Toyota's objective was to keep transmission fluid temperature near engine coolant temperature, I was always skeptical of @Krohsis reported thermostat opening at 245-250 degrees. At that temp level, WS fluid would already be degrading.

Your opening temperature of 200 degrees would make more sense for keeping fluid temp near coolant temp. Makes me wonder if @Krohsis ScanGauge wasn't out of calibration and showed high fluid temperatures across the entire range. Maybe he didn't need the secondary cooler as badly as his ScanGauge indicated.

 

There's actually no mystery in the design. That component that Toyota now finds convenient to call a "cooler", started life as a "warmer", and that's a purpose it serves well.

There are two primary parameters that make a difference in heat transfer: (1) Heat transfer surface area, and (2) temperature difference between the two media (delta T). There's very little heat transfer surface area in the warmer device on the side of the transmission. Just by looking at the outside of it, you can conclude the heat transfer surface area is probably less than the cooling tube once inside radiator tanks on automatic transmission vehicles.

Within minutes of startup, engine coolant temperature increases rapidly to normal operating temperature. The difference between the transmission fluid temp (near ambient) and the engine coolant temp is probably 80-160 degrees. The warmer doesn't have much surface area, but that temperature difference will quickly bring the transmission fluid temperature up to engine coolant temp. Once the fluid temp is at engine coolant temp, the "cooling" part of the equation becomes a little more sticky.

As a "cooler", with the fluid temperature near coolant temp, there is too little surface area in that warmer/cooler to really do any cooling. It theoretically does some cooling once fluid temp increases beyond engine coolant temperature, but to call it a cooler is a financial azz-covering joke. As operational heat increases in the transmission, fluid temp will increase well beyond engine coolant temperature to levels once thought unacceptable.

An air-to-fluid heat exchanger in front of the radiator is a different matter altogether: You can make this little transmission "radiator" big enough to provide the needed cooling (heat transfer area) without compromising engine cooling (blockage), and the delta T (media temperature difference) is ALWAYS at least 100 degrees. This line of reasoning was probably exactly what Toyota engineers thought when they added the first air-to-fluid cooler back years ago.

While the warmer IS competing with the air-to-fluid exchanger in front of the radiator by adding heat that the exchanger will have to remove, it is technically not a competition. The large surface area and large delta T of the air-to-fluid exchanger in the front can easily overwhelm the small surface area, small delta T of the transmission warmer, and still get the job done.

 

my co-worker and I talked about it and he was planning on bypassing the puck before he left the company. I even discussed it with the op. maybe it is somewhere in this long thread.

I think as @JohnLakeman was saying, it may not be that much heat coming in compared with what's taken out by the cooler but you are right they are opposing each other.

Another reason I didn't follow up with the bypass is cold winter days and the need to bring up the fluid temp. Also was worried about messing something up and causing leaks and warranty issues ... we have mild temps on W. side of the state but the E. side gets very cold. I Was also concerned about if I ever sell the car and the buyer moved to colder parts of state what would happen.

If I lived down south, I would definitely consider getting rid of the puck but our E. side of state gets very cold and I travel there frequently.

I would love to hear the results of someone bypassing the puck. Maybe you can report back.

 

Depending on your situation you could always just simply pin the thermostat open while towing, that alone would make a huge difference.

 

Once you understand the thermostat and warmer/cooler configuration on the 5.7L/A60 transmission, you'll understand why it will be nearly impossible mechanically. The transmission photo posted earlier is NOT the transmission used for the 5.7L.

 

I raised concern about his scan gauge and we compared scangauge trans pan/torque converter temperature code to be sure and we had identical code. Also his other temperature data (coolant and intake) were ok and comparable to my car & my scangauge. So I'm not sure what was going on.

He was very knowledgeable and was talking about the thermostat having some sort of wax that melts or softens as temp increases and may not be consistent between cars ... Don't recall the details but he talks about the thermostat wax in this thread.

 

In the older model that have a real trans cooler, doesn't the puck have a trans fluid IN and trans fluid OUT hoses? either that or maybe it has coolant In/out hoses ... Can't you just connect the two hoses and bypass the puck and also close off (seal) the puck in/out ports?

 

There's no way to trouble-shoot @Krohsis issue now, and it's irrelevant to him anyway.

We should assume that he was smart enough to systematically find the problem. If I was convinced the fluid temp was actually that high after trying a different OBD instrument, the logical first step would be to replace the thermostat rather than add another cooler in series. He was correct about the operation of the thermostat being dependent on melting wax, but any part can be faulty from manufacture or fail during service.