Transmission failures?

Hello all,

Since we all know the 2019-21’s had the transmission cooler removed by Toyota; Does anyone know of any failures from heat?


Is an additional cooler necessary for anyone who has owned one for a while and towed?


Thanks in advance, been tracking my temps and generally 190-220 F most days without hauling.

 

Numerous threads on here talking about the lack of coolers on these later 2.5 gens, but iirc no one has been able to point toward an overheating failure as of yet...

But, a few things to keep in mind is this:

These rigs are generally good and trouble free for 200-300k miles

When we do start seeing failures after 200k, is anyone really going to be able to point a finger (with absolute certainty) that it's a result of overheating.

Common sense tells us that each time ANY of our fluids 'degrade' from reaching a boiling point, being dirty, absorbing water, etc... we risk failure or a minimum a drop in performance (depending on the system the fluid is operating in).

For me, I've seen temps in excess of 230 while ambient temps were under 60 degrees and while NOT towing (minimal weight in the bed) during a short but steep climb on asphalt in my '21.

So, while I don't believe the liklihood of a 'catastrophic' failure is going to happen as long as I keep the fluid fresh, etc., I do believe that each time I see temps climbing that high, I'm degrading the fluid and making it (the fluid) less efficient at doing its job. The hotter the fluid gets the thinner it becomes and while that can smooth out shifting in some applications, the WS is already a fairly thin trans fluid. So, as our rigs start to age and require more friction for the clutches to grab and do their jobs and are wanting a thicker coating of protection to function smoothly, compromised fluids are certainly not going to help our cause.

Therefore, in analyznig the cost/benefit of adding a cooler to my '21, I considered the following:

Over time I may see longer service out of my transmission 300k is better than 200k or 250k (especially at current replacement costs);

If I do start towing, I can't imagine feeling comfortable as I watch temps climb into the 240-250 degree range... I don't want an unexpected failure when I'm on the road (it can ruin a trip / vacation real quick) especially when my family is with me;

At less than 1k for a quality set up, is it a good return on investment?? I believe so, even if it only produces an extra 50k of service life from the transmission;

Peace of mind matters and keeping those numbers low(er) under all operational circumstances HAS to be better for the transmission and the fluid that is supportiing its operation;

Can't think of ANY potential harm that could come from adding a cooler...

 

Well said! Great information, I’ll buy a cooler then. Just need to find a quality shop to help me install.

I’ve been measuring temps on scan gauge 3 and agree. Temps being that high make me nervous for longevity. I usually keep my rigs a long time, well over 10 years.

thank you again!

 

I'm adding one to my truck that I bought last month for peace of mind.

I pieced together my own kit similar to the genuine cooling systems. $700 total vs $1338.

I will install it myself. If I had no other choice than the GCS kit plus having a shop do it, total would be close to $2k. I would not add one for that price. At that point I'd put the $2k into an investment account and use it when and IF the transmission goes out. I would just do a drain and fill every 30k. This is assuming for infrequent towing. If the truck is towing often, them yeah good idea to add one even at $2k.

 

I know, the cost is a lot, but I do tow often, especially in Summers with 7 k trailer. I can do a lot mechanically, but never installed a cooler before. Would be worried I would mess it up. Is it fairly straight forward?

 

Every truck I’ve had or driven has had an average trans temp of 150-160 degrees. My opinion is that Toyota runs their transmissions hot to thin the fluid and help fuel economy. The same reason for the low viscosity transfercase fluid and 0w-20 engine oil. I pinned my thermostat and have been running Amsoil atf that has a higher heat tolerance to be extra safe and offer protection. My pan temp now stays around 150-170 at the most. I also have the added cooler on top of the factory cooler on my 18’.

 

https://www.tundras.com/threads/5-7l-transmission-cooler-kits.60550/

There's over 50 pages in the above thread w/parts list, complete kits, videos of the installs, etc... Spend a little time in there, and if you're comfortable w/what it entails you can save a few hundred on labor. Getting the hard lines lined up and installed are probably the most difficult but it comes down to the order of how everything is connected that makes a difference if you're fighting them or not.

If you don't feel comfortable with the install, I'd look to a 'competent' transmission shop that understands how to do proper service and drain and fills on our rigs, or a dedicated off-road shop that specializes or is highly familiar w/Toyotas.

You can also search the forum for additional info, suggestions, and feedback easily for this topic by clicking search; check 'search titles only box'; then type transmission cooler in the search field...

 

Yeah if you tow a lot in the summer it's a good addition even if you pay a shop. Like Tripleconpanna mentioned, there's lots of good info here. I'm no mechanic but I do my own maintenance and installs. If you ever swapped brake rotors or a radiator, you can do this.

Also, I'm very frugal and over analyze paying shops their labor rates for things I can figure out. If you have more money than time, there's nothing wrong with dropping the truck off and getting it back all ready to go!

 

Another option is if you're willing to share you location, members in your area can make recommendations on a particular shop or in some instances you may be near a member that has already done one on his own and would be willing to help w/the install (often for the large fee of a couple of beers)

 

Thank you all!

 

And a little more for ya...
https://m.youtube.com/watch?v=DyU3LIpA-Mg

 

It’s actually pretty simple to add the cooler if you’re mechanically inclined. The hardest part for most is setting the transmission fluid level.

 

A rock can hit your external fluid cooler causing a leak and you wouldn't know the fluid level was going down untill the transmission damage was done.

 

If you’re worried about that use a screen behind your grill.

 

So on Nov. 22nd 2023, the day before my scheduled open heart valve replacement surgery I went surfing and then went for a long walk on the beach just to gather my thoughts, and a guy came walking by wearing one just like that.

I remember thinking "Shit, what does he know that I don't?!"

*HA! Found it!*

 

did that happen to you?

 

I'll be a data point. I tow a boat an average of one hour (one way) two or three times a month. Staying in S4 or S5 and tow/haul on, I've never seen my scangauge over 210 in the summer. Usually hovers between 190-200 unloaded, I'm happy with that. Did the first transmission spill/fill at 20k, and I'll do it again at 50k and every 50k thereafter. I'm never dropping the pan or adding a cooler, let's see how long she goes

 

Sounds like a light boat and/or flat terrain. I’ll touch 220 going through the mountains with a cooler. Pulling about 6,000-6,500 lbs.

 

Definitely not.

 

But it could... monkeys could suddenly fly outta' my butt too, but the odds are pretty low.

My TT is 5,500 lbs. loaded (fairly light) but has a large frontal surface area (big parachute) and I tow at 62-65 MPH in S4 & Tow/Haul.

On the flats through the desert with ambient temps in the mid to high 80's she settles in at 210-212º and climbing grades it'll spike and then cool off nicely right away when I crest the grade.
Usually 225º-ish on the climbs, highest spike I've seen was 239º pushing it hard on a steep twisty 2-lane climb out of the desert from Imperial County into San Diego County.
You don't dare get out of line into the right lane 'cuz you might never get back over.

I pay close attention to TC lockup, and I'll slow on little rises to stay locked up when I can, &/or manually downshift.

If I towed heavy or more often I might add a cooler, but for now I'm good with monitoring temps and doing drain/fills every 30K.

 

That’s a great temp range, does s4 keep the pin open to drop temps?


Do you live in a cold area?

 

Yea def not a heavy boat. Loaded and gassed Im probably in the 3k-3.5k ballpark. No mountains either, but we've got decent hills depending on which direction you go. I was dead set on adding a cooler when I bought the truck, but seeing my towing vs unloaded temps it just wasn't worth it IMO.

 

New fear unlocked hahaha

 

those temps are awesome

 

231 is pushing it and there are only 2 ticks left til red - I like keeping things no higher than 200. With a cooler and fan mine achieves 170 at 80mph during 105 high humidity weather. Peaks (repeated stop/go reaching only 30 each time) in the same conditions just reach 200 and then drop fast once at cruising speeds.

Read thru posts a setup can be DIY for very little - the least being the Africa setup where no thermostat is used - just straight piping in/out to the cooler - this is using OEM parts. Or if in colder climates a thermostat would probably be healthier for the trans to warm up its fluid faster. Luck all.

 

For the first question, no pin on my thermostat. (99% sure)

And def not, I'm in Louisiana. Balls out hot summers, for sure. I just stay in S4 or 5 and try my best to keep it from shifting.

 

S4 is 4th gear which is direct drive (1:1 drive ratio). So the torque converter doesn't have to slip and generate heat in that gear, and that will keep temps down, to a point.

If you don't tow in S4 and keep the truck in drive it'll try and upshift to keep the RPMs down, and that will cause the torque converter to have to slip, and thus generate heat.

 

To @Johnsonman point, I just added a cooler to my wife's new (to us) 2016 Sequoia. Temps are almost 50°F cooler (previous peak before cooler 231°F, new peaks 187°F with cooler). It cost me about $360 and I installed it myself in about 3 hours.

There's a great thread on here titled "DIY Transmission Cooler for $300" or something to that effect, that I used as my guide. You can seach and find it easy enough

 

24 years ago I was driving a company work truck and this happened. We all hated that truck. A place down the road put a reman trans in with new cooler for 900 bucks. So we all had to keep driving it