When doing the full fluid exchange (in 2 quart increments) on my GX470 thru the trans cooler, I don't see clean/new fluid until I get to about Quart 15. I usually pump out about another quart before calling it quits. Not sure if you all have a different capacity than an A750F, or if that's just what it takes to get uncontaminated fluid out considering some of the new fluid will definitely be mixing with old during the exchange.
GX460 P2714 P0761 Ultimate Summary and Hope For A Fix Thread
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You actually don't want it to be a separate circuit, as the integrated radiator cooler both helps with warming the trans fluid during cold weather and cooling the fluid down when it exceeds the engine operating temperature of 195F (which it will most any time the torque converter clutch unlocks). You'd run the risk of having trans that shifts too hard during cold weather and still overheats when it's hot out.
The OEM Toyota radiator with a Hayden aux cooler works quite well, getting rid of the Toyota radiator for a CSF and still keeping the Hayden works even better.
Rebuild update: chased down the electrical problem. Neither temp sensor was reading. For the man trans elec connector on the drivers side of the transmission, it’s a plug with a latch that flips down for a “security” latch. I must have damaged something in the harness connection during tear down. If I flip the latch down, I get 6-12 electrical codes all related to what runs through the harness (temps-solenoids-TC). Unlatched every code goes away. The harness is still plugged in, but the secondary latch is not flipped down. Like new smooth shifts all around!
The only issue I had was a code thrown on solenoids C and D. For some reason the wouldnt shift 4-6 without resetting the code. I haven’t checked fluid level yet since I couldn’t read temps. This afternoon I will check level after the truck cools down. Current temps are 195-198. High. Could be low fluid level, and could be why I couldn’t catch 4-6 gears at 60 mph. Will update later.
Additional transmission cooler is about to be ordered. Any advice on that is appreciated.
The only issue I had was a code thrown on solenoids C and D. For some reason the wouldnt shift 4-6 without resetting the code. I haven’t checked fluid level yet since I couldn’t read temps. This afternoon I will check level after the truck cools down. Current temps are 195-198. High. Could be low fluid level, and could be why I couldn’t catch 4-6 gears at 60 mph. Will update later.
Additional transmission cooler is about to be ordered. Any advice on that is appreciated.
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Hayden 698 if you live in a cool climate, Hayden 678 if you live in a warm one where it rarely gets below freezing.
One thing I should have suggested to you earlier is replacing the wiring harness inside the transmission itself. I was getting a TCC lockup solenoid code on my 470 that I chased down to out-of-spec resistance in the interior wiring harness. A new one was $60 from Toyota and fixed the problem (along with some dielectric grease on the exterior flip connector). I think my harness was due to age; with you all having hotter-running transmissions it's certainly possible those accelerate the degradation of the harness.
That’s my current line of thinking. Install a 678, change the fan clutch, drive it another 2-3K miles. Pull the pan and change gasket/filter/all fluid that drains/wiring harness. Should be pretty tight after that.
Thanks!
If you really want to go crazy, you can also add a Magnefine filter into the ATF cooler plumbing. Mine is kind of jerry rigged (90 degree 3/8" SS smooth elbows) but does work quite well. I'm sure there is a cleaner way to do this; I just haven't figured it out. I replace these with every ~40K ATF exchange; they are around $25.
Do I need to remove the front bumper cover to install the transmission cooler?
At least on a 470 no; I happen to have mine off today as I'm installing a winch and aftermarket bumper
. However if you do need to remove it, at least on a 470, it comes off very easily. I also DIY'd the bracket for mine back in 2021 but it seems you all have many lower-priced aftermarket options today.
Really appreciate the guidance. I can turn a wrench, but the next best step isn’t always obvious to me.At least on a 470 no; I happen to have mine off today as I'm installing a winch and aftermarket bumper
Have you ever cut open the Magnefine filter to see what has collected in the media and on the magnet?
Acrad
GOLD Star
Just my opinion, but when I hear about products like AT-205, I think of them as a temporary fix—sometimes that “temporary” solution can last a couple of years—but ultimately it’s a stopgap until the underlying issue is repaired.
Yes - although I don't recall if it was for my PS filter or the ATF filter. The filter media was fairly clean and the magnet had caught almost nothing! It's probably an overkill solution, but is inexpensive and does not seem to hurt either as they have in in ternal bypass.
I am having a transmission overheating issue. Everything works great until the trans crosses 210+, then it goes into limp mode and won’t shift over 3rd until I clear codes. Takes about 40 minutes sitting in park idling before the temp falls back below 200. Temp gun on cooler lines only gives about a 15 degree difference with the return side at 188. Tomorrow I will attempt to flush the cooler just to see what comes out. I may try a flow test. Should have done all this before reinstallAt least on a 470 no; I happen to have mine off today as I'm installing a winch and aftermarket bumper
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First I want to thank all those who have helped figure out what’s going on, grate info!
I’ve got a 2018 tundra and 2014 GX460. The GX had the usual Code for a month and then reset the CEL on its own.
Reading that this is a heat issue and seeing evidence of that with the recent transmission rebuild it seems to be conclusive that it’s heat related.
For those who know me, love resolved heat related issues on 80 series trucks by modifying the performance of the fan clutch.
The 2014 had a burnt/orange colored hub while the 2018 had a black colored hub.
comparing the two they seemed the same.
I’ve modified the black hub of the tundra and will do the same for the GX.
Initially the start up roar is more pronounced and lasts longer. Which I would expect and has provided better cooling and AC performance especially at ideal. I’ll be modifying the clutch and installing that in the GX.
Then I plan to ad AT205 for a few drive cycles and then drain and fill with fresh fluid.
Unfortunately I live in the NorthEast and it’s now only 75*. So not much in the way of hard data.
I will be adding new Aisin modified clutches for these trucks on my site should someone what to try them.
I’ve got a 2018 tundra and 2014 GX460. The GX had the usual Code for a month and then reset the CEL on its own.
Reading that this is a heat issue and seeing evidence of that with the recent transmission rebuild it seems to be conclusive that it’s heat related.
For those who know me, love resolved heat related issues on 80 series trucks by modifying the performance of the fan clutch.
The 2014 had a burnt/orange colored hub while the 2018 had a black colored hub.
comparing the two they seemed the same.
I’ve modified the black hub of the tundra and will do the same for the GX.
Initially the start up roar is more pronounced and lasts longer. Which I would expect and has provided better cooling and AC performance especially at ideal. I’ll be modifying the clutch and installing that in the GX.
Then I plan to ad AT205 for a few drive cycles and then drain and fill with fresh fluid.
Unfortunately I live in the NorthEast and it’s now only 75*. So not much in the way of hard data.
I will be adding new Aisin modified clutches for these trucks on my site should someone what to try them.
Update: changed the temp range on my reader to 250 max. Temp today reached 172. Error codes by 160, went into limp mode ran with reader connected, clearing as they came up. City driving. Pointing more towards harness damage than overheating. Will see more tomorrow with a trip to the airport. Won’t have any more updates till next weekend with the aux cooler install. Currently running with the trans thermostat pinned open. Going to try to flush the rad/trans cooler before aux cooler install. May do a flow rate check. Results will determine if it’s a complete bypass set up or a series set up. Will be fabricating my own bracket(s) cuz I’m cheap and stubborn.
If your rig is >150K miles it probably needs a new radiator anyway. A number of radiators on GXs have failed (460s and 470s), usually causing the engine to blow a head gasket. I proactively did mine at 196K and honestly it was kind of stupid to let it go that long.
Interesting. My truck doesn’t blow any odd smoke. No reason to worry about valley/HG failure. BUT, I pulled almost a gallon out during trans removal (interchanger/thermostat device on passenger side), replaced almost a gallon on initial startup. Two days later, radiator took another half gallon to fill. Prior to second top off, never pulled from the reservoir after a couple hours of highway driving. Weird. Maybe I was low prior to trans removal, but I watch my radiators like a hawk because I’m not losing an engine due to it being thirsty, seems dumb. Really love the brass rad someone put in my LX450 before I got it. Wish we had an affordable option on the 460’s.
Heavily leaning towards a wiring harness replacement before everything is said and done.
By the way, after the rebuild, in 6th gear, I’m seeing a consistent 1500 RPMs, on the nose while cruising. Seems like a nice lock up.
They are known to burst without forewarning due to the plastic tanks. I spent the extra money on an all-aluminum CSF and am glad I did, but a new Denso replacement radiator is fairly inexpensive.
I don’t think this is the case. With older systems yes but in case the transmission has a thermostat in the circuit. It won’t circulate fluid until the thermostat opens.
This is one of the reasons I’m tuning the fan clutch. You can’t overcool the transmission but sure as hell can over heat it.