Install complete on additional transmission cooler

Hello, question of direction of flow on a 2015 with tow package. The hot atf fluid exits the tranny and goes through the thermostat body, with some cooling effect? Then it flows to the top of the external atf cooler on top of the AC condenser. After it leaves the external cooler does it go directly to the pan or back through the hockey puck? Thanks

 

The return line doesn't go back through the "hockey puck".

 

Thanks, Krohsis. I'm following your install. All four previous Toyotas with three still in use have no thermostat assembly.

 

Putting a new transmission in this truck costs about $4,500 plus labor.

If you're no longer under warranty or traveling through remote areas with a heavy load then it makes sense to spend a couple hundred bucks to upgrade the transmission cooling system and to change the fluid regularly. Whether it's necessary or not it's cheap insurance the way I see it.

 

Understand. I tow 6000 pound boat plus full load of teenagers. Temps are never below 100° for 4 months. The hill climbs out of the Colorado River valley are around 110° to 120° at just a couple miles, such as Willow Beach , Az but I can smell the cooking of fluids etc when I recheak the straps and hitch prior to getting back on US93 at road surface temps of 180° plus. I have a Derale 40 row electric cooler with 3/8 hose barbs I'm putting in. Mounting it is the difficult part but hoses are simple. Thanks

 

Just a follow up prior to installing atf cooler. With thermostat pinned open in 50-60 degree freeway speeds the highest temps where 175 with 154 being the average freeway temp with empty bed. Non pinned here are the pictures.

 

First picture is entering after entering the freeway, second is after exiting freeway stopped, third is after a couple minutes on the freeway.
Next thing I am trying is to see if pushing the pin at different depths changes the temps. I am just going to bend the pin further up with a screwdriver after its put in.
But so far I plan on pinning it open at all times. After cooler install I will post temps.

 

Please keep us posted. I like to know the results.
Thanks!

 

Hello, Here are the UltraGauge pics with the thermostat pinned open. The order is screwed up.
1st is exiting freeway, 2nd is constant 75mph, 3rd is prior to starting, 4th is entering freeway.

 

did you ever experiment with pushing the pin further up and what results did you get?
I wonder if it makes any difference. is there a lot of room to push the pin up & down?

 

Great commercial but I thought it was rather interesting the write-up about the commercial and the comments about transmission temps.

https://entertainment.howstuffworks.com/making-of-toyota-commercial1.htm

In particular "Every time the ATF rises 20 degrees above 175 Fahrenheit, the life of the fluid is cut in half." I am not sure where the author of this article garnered that information but I sure hope it wasn't from Toyota based on the temps we are seeing with our transmissions, LOL.

 

@Krohsis @acmesupply and anyone else on this thread or other tranny threads.

Who's still running with the thermostat pinned open?
Any issues at all?
Ever see overcooling?

I probably won't add another cooler, but I don't like the idea of the thermostat opening so late. I was considering this last year and my brain started pondering this again.

 

Has there ever been a definitive determination on when the thermostat opens? Still battling high temps (perceived) after installing the early cooler in line with the condenser cooler.

Cruising on highway: 30 degrees outside

 

The author is wrong when it comes to Toyota design. Tundra trans temp (once warmed up), will ALWAYS be above 175°F and typically in 185-200°F range under normal conditions (not towing) ... Based on what the author said, the fluid will have no life left after a few weeks but we hardly see any Tundra trans issues!

Author 175°F limit may have been from old days ... seems like with the new designs and synthetic fluid, etc. 175-225°F is the normal and acceptable range.

 

From what I've read the high temperature heat cycles are hard on conventional fluids, but they also cause problems with the seals, electrical wire sheathing and plastic electrical connector clips inside the transmission. Traditionally, all of these components would become brittle after several high-temperature heat cycles and start breaking.

We've benefitted from a few decades of research in high temperature plastics since that old rule-of-thumb temperature limit was established so who knows what the real limits are now.

 

I live in the hot Mojave desert. I pin the thermostat open in temps over 70F which is 9 months a year. It is roughly a 30F degree difference overall in terms of cooling. The thermostat opens on mine at @240F and off at around @225f.
No issues at all here and I am going to leave it pinned this winter. The tranny fluid in the TC heats up very fast and the pan is not far behind in all temps. Maybe 3 times faster than the coolant.
I never see overcooling as the temps are always above 135 minimum even in freezing temps. The hottest was towing a boat in 120F air temp up a inclined road which barely hit 242F.
I did check the over temp a few days ago and the alarm is at or near 300F. It would not go off until is hit 285F or so. The 300F level was quickly obtained by just pressing on the brakes and keeping the rpm at 2000rpm.
It took a mere 30 seconds to hit the alarm from a starting temp of 160F.
I'll take a cooler running trans by @30F any day. If you look at atf temps charts, 175F is usually the lowest temp on the scales for fluid breakdown. Yes, higher temps burn away moisture etc. but in a sealed system with no combustion just wear particles and metal is present. That's why I use a Magnafine atf filter from day one.

 

Did you have the thermostat pinned when it hit 242F?

 

Yes it was pinned open all summer. Average temps in normal driving with it not pinned open in the summer are 185F to 220F on the TC and 180F to 200F on the pan temp.

 

acmesupply,

Great info but I'm a bit confused. Did you have a factory cooler and install the Derale in addition or is the Derale your sole cooler?

Could you post a picture of the cooler install, most interested in how you mounted it.


Greg

 

I have a 2015 lease that ends in December and will be buying a 2019 so I have my cooler and mount ready to go on the new one. I will take some pictures of it and my mount after work.

 

@acmesupply

I assume that the 240f for the thermostat to open was on the pan temperature correct? How did you determine that was the open/close temp? Thanks!

I still feel my temps are too high. 36 degrees outside, cruising on the highway tonight from the airport, seeing these temps were way too high for me with both coolers (makes no difference if fluid is not flowing to them)

This was after it hit 230 in the TC.

 

The transmission oil cooler thermostat is not controlled electronically by either of the two temperature sensing units.

It is controlled mechanically within the thermostat itself, measuring the temperature of the oil as it enters the thermostat. Think of it as a glorified pop-up indicator one uses to know when a turkey is done but more complicated.

Now, the question is where is the thermostat located relative to the two temperature sensors? An educated guess would be that after the oil passes through the thermostat and the cooler, it then goes into the pan. Any temperature fluctuations in the oil pan temperature would be gradual, due to the mass of the oil in the pan.

However, the location of what we refer to as the torque convertor temperature sensor (Toyota never refers to it by that nomenclature, just ATF temperature sensor No.2) in the oil flow path is not known, at least, to me.

Monitoring temperatures in extreme conditions can most likely provide a clue. If one sees a dramatic drop of temperature in ATF temperature sensor No.2 at a certain temperature point, bottoming out and then climbing again, one can assume that it is measuring the temperature after the cooler has been added to the circulation path. Given what acmesupply is reporting, I'm guessing that this is the case.


Greg

 

So what’s the general consensus here?

I added the auxiliary cooler on my taco for my camper, but the process was a bit more up front.

I’m planning on traveling from N.C. TO Utah this summer and want to make sure I’m not going to overheat towing my 7,000 lb camper.

I have a scangauge to monitor, and winter temps stay fairly cool with a pinned thermostat. Hottest was 205 up 16 mountain (slow 5-6 mile curvy 5% ish grade)

 

Stay with the aux cooler with extra spare atf in case it spurts or overheats. Maximum flow of air and of atf in the mid engine range so no lugging the engine. Large difference in atf flow at idle compared to 3000 rpm. Atf is the main coolant. I have a 1995 and 2002 tacoma but unfamiliar with more recent. You want full flow through the cooler . I see on I15 in Utah lots of overheated cars and trucks. Lots of hills and hot in the summer with cool nights. I run 30/70 antifreeze /water.

 

Sorry, I should clarify.

I added an aux atf cooler to my taco whic was stupid easy.

Now I am debating doing the same to the tundra and I cannot find a step by step like on Tacoma world.

Looks like the lines are on the passenger side running into and out of the radiator. And not exact on how the set up like the op set up his cooler.

I’m not super mechanical but can run lines, just don’t want to f up $4,500 trans

 

All 2014-2018 tundras with tow package have a built in thermostat controlled atf cooler on top of the ac condenser just in front of the radiator. You can see lines coming in that are on top. 3/8 inch hose line assembly .If yours also has a tow package pin open thermostat so full flow atf through the cooler all the time. I would say the stock cooler and drive in S4 with tow haul mode will be the best option in the hills and mountains .

 

What fittings did you need to finish this out, and how much hose?

 

To piggy back on the previous question, what trans oil did you use and rough figure of how much. Just changed stock brakes to ebc rotors and yellow stuff brakes. I hope to do this before my trip to Utah from NC.

 

Interesting new developments for the 2019 Tundra's, they no longer use a traditional transmission cooler. Meaning there are no transmission lines running to any kind of radiator at the front of the truck. Instead they now run engine coolant lines back to a heat exchanger outside of the transmission (hockey puck looking device). I confirmed this with a Toyota tech, and he's researching if any techs have published a way to add one.

I still have the same heat issues that previous owners have had. So right now the only options I can think of is add an electric Radiator fan for additional cooling over all. And possible adding a small remote electric cooler on the undercarriage of my truck and cool the fluid before the heat exchanger. See picture.

Thoughts?

 

The old models had a heat exchanger also. Is the new heat exchanger different or bigger?