GX460 Transmission fluid cooler

[rav8]

How long of a drive? Mine takes a full 20-25m to go from cold (az cold, not actual cold) to 180. Are you sure you hot the 698 and not 678? Maybe your bypass is stuck open? The stated temp is 180 on the hayden so if yours never hits that, Im not sure what you’ve got going on.

Have you guys considered that too cold is bad too? 160 sounds great, but I have to think Toyota put a thermostat and warmer in for a reason. Cold fluid is higher friction and viscosity. I would think there is a very specific reason Toyota went through all the trouble of bypassing their own cooler at a decent engineering complexity cost.

Earlier...

Toyota designs some good stuff. There are reasons that they incorporated a thermal bypass (warmed by engine coolant) before sending to a cooling path. I try not to outthink those who designed that system. My application (towing 4K camper ~10K miles total yearly) benefits from having an additional passive cooler. That said, I want the factory bypass to control that function. Having an additional non-functional stat adds no protection or capability that I am aware of.

 

[WTITW]

Toyota designs some good stuff.

Im in this boat mostly, but I did do a little digging and it looks like Toyota only started putting warmers and thermostats in in the 2000’s so @Cold Iron might have something when it comes to why they exist being tied to emissions. I used chatgpt though, so who knows : ) @Acrad is in the pin the therm group. Can you find out when they started adding them?

 

[Acrad]

The GX 470 didn't have the thermostat

Not entirely sure on the Tundra for example... seems might have been as early as the '07 Tundra if it had the tow package

2008 Tundra with Transmission cooler de pin

Are these models with transmission cooler able to be de pinned?

www.tundras.com

I'm fairly sure all 200 series have it

 

[WTITW]

Yeah. The 2007 Tundra is the one Chat found for me.

 

[Cold Iron]

Im in this boat mostly, but I did do a little digging and it looks like Toyota only started putting warmers and thermostats in in the 2000’s so @Cold Iron might have something when it comes to why they exist being tied to emissions. I used chatgpt though, so who knows : ) @Acrad is in the pin the therm group. Can you find out when they started adding them?

CAFE came out in the 70's as a result to the Arab oil embargo and gas wars. And every stretch of mpg target goals gets stricter and stricter with larger penalties for those that don't.

It isn't just Toyota that puts in Transmission warmers and is looking to increase fuel efficiency to prevent penalties . Toyota is a usually slow to change thank goodness.

Research and studies done by individual automakers is proprietary and not shared as a rule. And public domain research usually requires a subscription or pay per view (read). But found an open domain study published by the Society of Automotive Engineers titled Investigation of Transmission Warming Technologies at Various Ambient Conditions that you can read.

Note the Introduction:

Introduction:
In 2012, new light-duty fuel consumption standards were set for the North American market. The U.S. Environmental Protection Agency (EPA), National Highway Traffic Safety Administration (NHTSA), California Air Resources Board, OEMs, non-government entities, and other stakeholders collaborated to define the 2012–2025 national fuel consumption and greenhouse gas standards. The program called for a 4%–5% annual improvement in fuel consumption with the final car and light-duty truck standard set to 54.5 miles per gallon [1]. Vehicle manufacturer fleet fuel consumption certification for this Corporate Average Fuel consumption regulation is determined via a combination of on- and off-cycle methods.

 

[WTITW]

found an open domain study …. that you can read.

Cold Iron. Please. We come to forums to make conclusions that fit our world view. Not to “LEARN FACTS”.

This is great. Lets find one that examines atf temp vs transmission life. If there’s no negative effect of running below 170 I’ll pin mine.

 

[Cold Iron]

Cold Iron. Please. We come to forums to make conclusions that fit our world view. Not to “LEARN FACTS”.

This is great. Lets find one that examines atf temp vs transmission life. If there’s no negative effect of running below 170 I’ll pin mine.

An oldie but goodie, not specific to Toyota but still very valid today.

Living in the Valley I wouldn't hesitate to pin that bitch all year. Even without a Tstat in an external cooler. Only time I'd run both Tstats is in the frozen Tundra where I live in the winter and if I could would bypass the external one. Wait, that is what the Tstat in it does. I will be pinning my OEM open in another month or so.

 

[fadkar]

I have a 2022 GX460 with 34K miles. I don’t tow or off-road much, but I live in California and occasionally drive up mountain roads to access hiking spots and national parks. I've noticed a burning smell outside the vehicle after climbing, and the intensity seems to correlate with the steepness of the incline.

After some research, I found that this seems common, though there’s little concrete info on the cause. Based on this thread, I suspected ATF overheating due to the inadequate cooling setup. Using my OBD device, I took the GX up a local mountain road that has a mild but consistent climb, staying in S4 at 35–45 mph and occasionally dropping into S3. AT1 (pan) temps quickly rose to 212°F and stayed there the entire climb, regardless of gear selection. After about 25 minutes, I parked and noticed a mild burning smell.

On the descent, temps stayed below 190°F, and there was no burning smell. This suggests that keeping ATF temps under 200°F may help prevent the issue. To address this, I ordered the OEM cooler and plan to do a fluid exchange before retesting AT1 temps on the same route and will report back. Special thanks to Arcad and everyone else who has shared information on the various forums! I'm glad I was able to get educated on the "lifetime fluid" myth before my GX racked up too many miles—better to address it now than risk potential issues down the line.

 

[fadkar]

I have a 2022 GX460 with 34K miles. I don’t tow or off-road much, but I live in California and occasionally drive up mountain roads to access hiking spots and national parks. I've noticed a burning smell outside the vehicle after climbing, and the intensity seems to correlate with the steepness of the incline.

After some research, I found that this seems common, though there’s little concrete info on the cause. Based on this thread, I suspected ATF overheating due to the inadequate cooling setup. Using my OBD device, I took the GX up a local mountain road that has a mild but consistent climb, staying in S4 at 35–45 mph and occasionally dropping into S3. AT1 (pan) temps quickly rose to 212°F and stayed there the entire climb, regardless of gear selection. After about 25 minutes, I parked and noticed a mild burning smell.

On the descent, temps stayed below 190°F, and there was no burning smell. This suggests that keeping ATF temps under 200°F may help prevent the issue. To address this, I ordered the OEM cooler and plan to do a fluid exchange before retesting AT1 temps on the same route and will report back. Special thanks to Arcad and everyone else who has shared information on the various forums! I'm glad I was able to get educated on the "lifetime fluid" myth before my GX racked up too many miles—better to address it now than risk potential issues down the line.

Also, in retrospect, I would have went with a larger Hayden cooler for even better cooling but I ordered the OEM stuff a few months ago before diving super deep into this thread. Given that I don't tow much, I'm hoping the OEM cooler + 30k fluid exchanges will be enough to make the trans last 200k+ trouble free miles.

 

[r2m]

I have a 2022 GX460 with 34K miles. I don’t tow or off-road much, but I live in California and occasionally drive up mountain roads to access hiking spots and national parks. I've noticed a burning smell outside the vehicle after climbing, and the intensity seems to correlate with the steepness of the incline.

After some research, I found that this seems common, though there’s little concrete info on the cause. Based on this thread, I suspected ATF overheating due to the inadequate cooling setup. Using my OBD device, I took the GX up a local mountain road that has a mild but consistent climb, staying in S4 at 35–45 mph and occasionally dropping into S3. AT1 (pan) temps quickly rose to 212°F and stayed there the entire climb, regardless of gear selection. After about 25 minutes, I parked and noticed a mild burning smell.

On the descent, temps stayed below 190°F, and there was no burning smell. This suggests that keeping ATF temps under 200°F may help prevent the issue. To address this, I ordered the OEM cooler and plan to do a fluid exchange before retesting AT1 temps on the same route and will report back. Special thanks to Arcad and everyone else who has shared information on the various forums! I'm glad I was able to get educated on the "lifetime fluid" myth before my GX racked up too many miles—better to address it now than risk potential issues down the line.

I too live here, in So. Cal, not sure what part of the state you're in, but yeah, going up into the local San Bernardino mountains, Grapevine, Cajon Pass, etc. I always use manual shifting, even when I'm going down the grades to help keep my foot off the brake on those long grades.
Having your trans temps hit 212° F is not too high. Start worrying when they're above 220° F.
Try using manual shifting and drop it down to 3rd or 4th gear when your on those grades and traveling about 35-40 MPH.
I've found manually shifting will lock the trans into a gear and keep both the torque converter and trans temps lower. Plus, if you've ever driven a manual trans, it's just fun to shift again! (but without the clutch)

 

[WTITW]

Went up to Prescott and back over the weekend. Ambient was low, like in the 60’s at most. Still saw 210 pan temp momentarily on a climb even with the new cooler and this was with no tow vehicle…. I might be rethinking that thermostat pin unless the temp are essentially identical towing my 5500lb trailer… which I doubt.

Average pan temps seem to be about 10ish degrees less before the cooler, just not sure that’s enough.

 

[Cold Iron]

Went up to Prescott and back over the weekend. Ambient was low, like in the 60’s at most. Still saw 210 pan temp momentarily on a climb even with the new cooler and this was with no tow vehicle…. I might be rethinking that thermostat pin unless the temp are essentially identical towing my 5500lb trailer… which I doubt.

Average pan temps seem to be about 10ish degrees less before the cooler, just not sure that’s enough.

Jake I do appreciate your careful and thoughtful approach to pinning the factory thermostat. Given your physical location however it is time to open your Engineers Junk Drawer and find a cotter pin of the correct size and pin it open. And just leave it there all year.

Coworker and good friend and his wife are flying into the Valley tomorrow morning renting a car and headed up to Sedona and surrounding area for the next week. 6+ inches of new white chit supposed to start dumping here later today so they are leaving this afternoon to stay at a hotel across from the airport so that they don't miss their flight due to road conditions driving an hour and a half in a snow storm. Going to be at least a month likely longer before I pin mine open.

Last year we just finished doubling the size of the campus in Scottsdale. Yesterday it was announced that now we are spending $1.9 Billion to add an additional building on the East side of the hospital. As tempting as it is, especially this time of year, to move there not going to happen. If you can't wear a flannel shirt at least 6 months of the year then I'm not interested If I were to end up there I would pin mine open before I left.

 

[BC11SVT]

Also, in retrospect, I would have went with a larger Hayden cooler for even better cooling but I ordered the OEM stuff a few months ago before diving super deep into this thread. Given that I don't tow much, I'm hoping the OEM cooler + 30k fluid exchanges will be enough to make the trans last 200k+ trouble free miles.

I'm sure you could make the Hayden cooler work with the 2 OEM ATF hoses in the engine bay and the OEM hard line assembly/seal that runs through the radiator support.

It's a very clean setup and I would try to use them with any auxiliary cooler install personally.

This part:

 

[Banandalorian]

I've found manually shifting will lock the trans into a gear and keep both the torque converter and trans temps lower. Plus, if you've ever driven a manual trans, it's just fun to shift again! (but without the clutch)

Too bad Toyota and almost everyone else does their manual shifting backwards on the gear selector. The correct way is that you pull back to upshift and push forward to downshift. This is a statement of fact for which I will accept no counter-argument.

 

[r2m]

Went up to Prescott and back over the weekend. Ambient was low, like in the 60’s at most. Still saw 210 pan temp momentarily on a climb even with the new cooler and this was with no tow vehicle…. I might be rethinking that thermostat pin unless the temp are essentially identical towing my 5500lb trailer… which I doubt.

Average pan temps seem to be about 10ish degrees less before the cooler, just not sure that’s enough.

Was this with the trailer?

 

[r2m]

Too bad Toyota and almost everyone else does their manual shifting backwards on the gear selector. The correct way is that you pull back to upshift and push forward to downshift. This is a statement of fact for which I will accept no counter-argument.

Well....
If you're talking manual shifting, then it depends upon who the manufacturer is:

Sometimes 1st gear starts at the top, sometimes at the bottom.

 

[Banandalorian]

I meant the automatic shifter in manual mode - in the GX and other Toyotas, you push forward to shift up a gear and pull back to downshift. It should work the same way as a sequential manual in a race car where you pull back to upshift and push forward to downshift.

Manuals aside from dog-leg racing boxes (or very old cars) have first in the same top left position even though they may move reverse around.

 

[evolute]

I'm sure you could make the Hayden cooler work with the 2 OEM ATF hoses in the engine bay and the OEM hard line assembly/seal that runs through the radiator support.

It's a very clean setup and I would try to use them with any auxiliary cooler install personally.

This part:
View attachment 3852575

I am in the middle of designing this exact product. Designing my own bracket to incorporate the oem bracket that attaches to the radiator support as well as the cooler lines that go through the radiator support. It will be made out aluminum and using all(hopefully) oem hardware. It will be able to fit a Hayden 678/698 or a comparable sized PWR/c & r racing cooler manufactured in Australia.

 

[WTITW]

Was this with the trailer?

Unloaded. Didn't even have the dog.

This part:

I think I need that bracket and the hardline passthrough. That would give me a lot more peace of mind. Is that part the same as 32907-60290 that @Acrad posted on page 1?

 

[evolute]

Unloaded. Didn't even have the dog.

I think I need that bracket and the hardline passthrough. That would give me a lot more peace of mind. Is that part the same as 32907-60290 that @Acrad posted on page 1?

That is the pass through. If you want the bracket that attaches the pass through to the radiator support then you also need
1x3291360260-bracket
2x9008011589-2 bolts