2022 Tundra Suplemental Transmission Cooler?

New trans thermostats are $130. Not too bad

 

Based on this diagram for the hybrid transmission the T-stat can be pinned open.

 

Reading the last several posts, adding an external cooler does not have the same ROI as my prior experience with 700R4 or 6l80 due to the bypass at the transmission.

I need clarity before I install a cooler:

• Trans mounted bypass allows fluid to the external cooling circuit at 195. I suspect the thermo control is a wax based device, is it fully open at 195 and actually cracks lower, say 165?
• With the bypass in place it's unlikely to see a long term trans temp below 195, even with external cooler?
• Adding the cooler is limited to reducing temp spikes due to addition BTU shedding?
• If there a detailed explanation of the trans cooling design functionality? If the trans bypass is closed until 195, what is the purpose of the puck before the in rad cooler?
• While we know keeping the trans temp 180ish is preferred, other than potential major inconvenience of a repair, is adding a cooler worth the risk with a 6/60K defaults or in my case 10/125K warranty?

At this time, in my case, serious consideration to leave as is. Once outside the warranty, then address the bypass and add external cooling capacity with a 13011 and adding the 46K BTU unit.
Comments?

 

figured it would be there if it was possible. Thanks! Looks like I'll be pinning it this weekend.

 

I will attempt to answer some of these questions from post #213.

Based on my finding on my hybrid truck the fluid stays in the transmission until around 195 degrees.

In the "stock" configuration I would say yes

It would limit temperatures above 195 degrees, but never go below that once up to that tempature.

I had the exact thoughts! What I do know id the fluid leaves the transmission then goes into the bottom of the radiator and out into the puck.

 

Bear in mind in my industry we don't start getting much information for new transmissions until they have been in the field for several years and maybe sooner if there are higher failure rates. Yes the cylinder should be where the valve is. What would be ideal is an aluminum machined flat plate in the same shape with the same mounting holes and two dilled and tapped holes in the plate for fittings where the input and outputs are on the case. I may end up buying a valve and take it to the technical school I have a relationship with to see if they can machine a plate with fittings in their machine shop class.

 

I wonder if we can swap in that thermostat with 2 outputs and 2 inputs. I like the older design and it's function was simple it warmed the fluid when needed and cooled as needed with the different outputs. Our thermostat looks to have a similar bolt pattern too but not sure about mating surface and if the fluid ports land in the same spot as the older transmission casing.


I plan on modifying the return line to the transmission if the old thermostat doesn't work and see if I can add a thermostatic valve to feed a cooler over 180F. Mishimoto makes some nice valves with -10 fittings but I really hope the engineers were lazy enough to not change the bolt pattern lol. The main question for me is the duty cycle of the current thermostat on cold starts it should be open to warm the trans fluid right? It can't close to cool itself so does it always stay open? I hope we can get more info on the new thermostat this truck is no fun in the heat.

 

This is a common mod on nissan CVTs and they did the same thing youre thinking about. Grab an oem tstat...copy the footprint and machine a block of aluminum with the passages you want and tap the ends for fittings of your liking.

 

If the suspect cooler/heater valve does in fact have a "pin" it would make sense that doing so would be a place to start before adding the cooler. If you do the transmission fluid level check you would want the thermostat pinned to ensure the entire system was charged with fluid (like my 2016 tacoma which I added an external cooler to inaddition to the oem tow package cooler). Since I have the cooler on the Tundra already, and if the thermostat can be pinned the results for cooling should be pronounced. I don't see any downside to doing this as if it does run cooler it will lengthen the life of the transmission and fluid. Come Winter and non-tow season you simply remove the pin. I will be crawling under the truck soon to verify and pin if found. As for warranty impact - if something would happen the unit can be removed so there should be no signs of it ever being utilized - however you would have to do a fluid level check to remove the amount of fluid added. Personally I'd rather have it run cool and take the risk than let it burn and fail even if it would be replaced under warranty.

 

if that is in fact the case then you have found the solution. My Tacoma had this and all I had to do was pin the thermostat during tow season - it allowed the additional cooler to function, then un-pin it during non-tow season (winter). Thanks for doing the research. I will be crawling under the truck to take a look.

 

If you pin the bypass to 100% open, then add a 13011 that cracks at 165 or a bypass from Improved Racing where you select crack from 135 to 165, would you need to make the seasonal adjustment? Have to think if plumb to the OEM + cooler in the winter to keep heat in the system or just the external cooler like a 56KBTU unit for warmer climates. Its really replacing the factory bypass with a lower temp device.

 

There is only open (100%) if you pin it. I did not use a bypass - but is sounds like you could use it as you note for seasonal and leave the oem trans thermostat pinned all the time. Good idea! It does not take long for the fluid to reach operating temp so I would not worry about the transmission running cold in the winter - I think once the fluid is 100 degrees the transmission will allow full lock up for the torque converter.

 

I bit the bullet and bought a T-stat today for my 2024 Tundra Hybrid. I want to get this heat issue resolved before my next camping outing.

In this picture the T-stat came with the pin as shown on the left side, but not the o-rings. That is a separate purchase. Of note: My thermostat is different than the one posted in post #202.


Back side. I think it is funny they put caps where the transmission lines go, but the back is open and the machined face outside of where the o-ring would sit has been damaged! The stealership charged me $198.00 to put in my hand!!





Same as what is on my truck. The black is over spray is from the undercoating.

By putting in the pin the fluid should flow as soon as the truck is started and not reach 195 degrees before leaving the transmission as in my case.

This helps, but I am still going through the lower radiator and the puck. Depending on how long a drive towing (10 -12 hours or longer) the temperature will eventually climb back up. I want to bypass both the lower radiator and the puck for the summer use and return it to stock for winter.

Here is a question that has me concerned.

1) When bypassing the lower radiator and the puck the transmission oil will still be in there capped (not sure what method I will use) not circulating all summer and be subject to follow the engine coolant temperature. I don't know at what temperature the transmission oil will break down? I don't want to reconnect everything in the fall and have the oil beyond its life cycle.

2) Should I just blow the oil out of both the lower radiator and puck and add the necessary oil back in the fall?

 

Pic on #202 is a Gen2.5 unit.

lost me a little bit - the transmission Tstat you bought is exactly like the one on the truck ?

The one on the truck has had the pin taken out - which would be normal as this enables the Tstat?

I don't plan on circumventing the system with a complete bypass so I'm not sure about removal or capping. MaxPayne3 will know that. As for fluid temps and related impacts see the chart below. Conversion is degrees C x 9/5 + 32 = Degree F (90 degrees C = 194 Degree F),

 

Just blow it out, cap the lines and add fluid when/if you reconnect it. I plan on doing a full bypass and never reconnecting. We don't see anything below 40 during the day...night time.might drop into the 20s but that's it.

 

you are going to see some much cooler temps! Thanks. Was 100 + here yesterday in the garage - lower temps today so hopefully I will get to mine soon.

 

My TBSS 4L70 running a 32KBTU after the in radiator cooler stayed under 195 when towing boat (3500-4000#). Granted, the ambient was 70-80s. You may be ok with your huge 56KBTU up front keeping the OEM puck, it's small.

When I do execute the install, my current plan is to:
- pin the OEM bypass
- install 13011 between trans and puck essentially replacing the trans bypass as it cracks at 165
- serious

Improved Racing FSC-145 Compact High-Flow 145F Engine & Transmission Oil Cooler Thermostat, 6AN

considering improved unit at a lower crack temp
- install 46KBTU post existing OEM
- install is permanent, do not want to switch for seasons

My primary towing is boat to ramp (20 mile), with 3x year 200mile trips. I do tow car to track (6.5K-7K) few times a summer.

EDIT: I need to fall on sword for inability to interpret diagrams first time right. When I looked at the flow diagram, I failed to recognize the engine coolant line from the radiator to the puck, thinking they were trans fluid going into the rad (duh!). I now see the puck as the only trans fluid heat exchanger. Yea, adding a external cooler is getting closer in my future.

 

got 215k out of a 4L60 in my 05 CCSB with a bypassed 40k tru cool. cooler fluid def helps, imo.

 

Trans bypass valve thermostat pinned. Highway tomorrow. System is basically same principle as I have on my Tacoma (although I used a Hayden on it) with thermostat pinned - ran mid 170 highway and 190 top towing and is a Super Charged AT V6. Over 60k miles on the SC and cooling system and zero issues.

 

maybe thats all we end up needing

 

We will know soon!

 

If you don't cool it after it leaves the puck (return flow to transmission) it will be roughly your radiator fluid temp.

 

then nevermind...I'll have to pin and bypass

 

For the external bypass, need to decide 145 or 165 crack temp. Documentation states valve flows 10% even when closed. Looking forward to results from @2024 Tundra and @303Gen3 and/or comments from @MaxPayne3 to make choice. I'm in the north with winters that can hit-20F in the morning. Leaning toward 165 -. Funny how I was not the least bit concerned with the 4l70 running cold in the prior vehicle.

 

I'm base elevation 5800 ft. (Rocky Mountains). I never have had a low temp issue with my Tacoma in the winter or cold temps (sub zero to freezing but I do garage). Turdra has the same environment. I am confident in the solution.

I'd go 145 if it were me and corrected to agree with the MAN that does this for a living!

 

I would go with the lower temperature, 145 degrees. Once the thermostat reaches its setting at 145 degrees it will open and stay open unless the temp drops below 145 then it will close again. 145 is a great temperature for a transmission. I'm in the Phoenix metro area and when we get 105 plus degree temps, my 4L70 in my El Camino never gets over 165 degrees. On track days same thing, my external fan on my trans cooler never comes on.

 

okay initial results:

outside air temp 92

took a 30 mile drive on local streets (40 mph) with stop lights about every 1/4 mile. Oil and Trans fluid temps were 95 to start. Finished with both at 160. Radiator was 190.

second leg after a 20 minute stop to pick up grandkids - 30 minutes at 65 mph. Engine oil and trans fluid temps 174, radiator was 190.

I'd say the missing link was pinning the transmission thermostat. Don't think I will be going to a larger BTU unit based on these results, but I will be pulling the camper in a few weeks so we shall see.

Anyway you cut it if you want your truck transmission and engine oil temps to run cooler you need to add the external cooler and pin the thermostat.

 

Where is this thermostat and how do we pin it? SR5 4x4.

 

passenger side of the transmission....has 2 lines connected to it. Look at pics posted here, youll see where the pin goes...1.5mm diameter