GX460 P2714 P0761 Ultimate Summary and Hope For A Fix Thread
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Interesting! Thanks for this info!
Have you ever seen it fixed with your vehicle or a members? I have not seen this brought up in this entire thread unless I missed something. I don’t even know the cost or part.
The tech did say before it warms up they could hear a bit of a whining noise from the ATF pump. Not sure if that operates with the drum.
Agree 100%. These problems don't occur in the A750F, which started rolling off the Tahara assembly line nearly 24 years ago in the GX470. Presumably the seals are the same or similar materials as the transmission share a common architecture, which would certainly indicate this to be a temperature problem.
Update: 6 hours in today. I don’t have pneumatic or mechanical power tools to speak of. I used 2 different breaker bars and 6 different socket wrenches today. My truck is rust free. Will be pulling the trans tomorrow. Toughest part so far was pulling the exhaust manifold. Must remove the oil dipstick to help. Heat shields are a PIA. So is the forward end of the front drive shaft. Exhaust manifold removal is absolutely necessary. Rear driveshaft can be left attached to the rear differential. 6 bolts flywheel to TC.
I’ll add: Not to offend anyone, but if you have not previously removed an engine or a transmission, I don’t recommend this transmission removal as a first time job. Some steps are old hat from previous projects. Some steps are not immediately intuative.
I’ll take a ton of pictures starting tomorrow after the trans is out. If you are interested in anything in particular, please let me know. I’ll get plenty of pics of the bonded seals during tear down. I believe that’s where all of these problems originate.
Another note: this V8 is crammed into a small engine bay. There are heat shields EVERYWHERE. I can’t see this engine/trans getting good air circulation. Likely contributes to the high temp these packages produce, eventually cooking all non metallic components in the trans.
Also, I have a 1997 LX450 that I’ve rebuild the engine in. IMO, the GX460 frame, brake system, drive shafts, differentials, and undercarriage coatings are all far far superior than the LX450
Guys, no need to over complicate this. Read about AT205 it’s a plasticizer not a solvent. Watch the videos I posted on the last page. It restores the chemical used during the manufacture of O Rings to make them soft. This is the chemical which leaches out under heat and over time. It’s a unique product not like other stop leaks. Much easier to add 1 $20 bottle to tranny than all the work our brother @gsi18867 is about to undertake. (I feel your pain btw!)
Yesterday I changed the engine oil in my GX for the first time since Aug 2024. Only added 4500 miles since then stuck in 4th gear and under. I scheduled an alignment for this coming Weds… and I washed the algae (yes green algae!) off the hood and door handles that had accumulated after it had sat for an entire year due to codes and non working reverse gear.
I’m now 250 miles since adding AT205. Driven in D to work the last 3 days 20 miles each way in South Florida traffic and freeway use. Reverse has been 100% working and I’ve engaged it at least 40 times. I engage it every chance I can get to check. My GX has now come out of retirement and back to daily duty.
Someone else needs to try a bottle but I’m now very confident this is the easiest fix and the value is insane.
Yesterday I changed the engine oil in my GX for the first time since Aug 2024. Only added 4500 miles since then stuck in 4th gear and under. I scheduled an alignment for this coming Weds… and I washed the algae (yes green algae!) off the hood and door handles that had accumulated after it had sat for an entire year due to codes and non working reverse gear.
I’m now 250 miles since adding AT205. Driven in D to work the last 3 days 20 miles each way in South Florida traffic and freeway use. Reverse has been 100% working and I’ve engaged it at least 40 times. I engage it every chance I can get to check. My GX has now come out of retirement and back to daily duty.
Someone else needs to try a bottle but I’m now very confident this is the easiest fix and the value is insane.
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Absolutely. If an additive can get you back to good performance, put it in. Don’t go for a rebuild. I already had my parts and jack delivered when you posted otherwise I’d try it. But I had already tried Lubeguard several times with no results. I was starting to get a real rough shudder in reverse (when it would go into reverse) and plan on heavy towing soon. I’m not convinced the dried seals/orings are my only problem.
Great to see positive results with an inexpensive option. Please keep us updated
I think what you all are going to find is that re-plasticizing the seals may address a symptom of a trans that runs too hot (potentially with the side effect of causing clutch slippage like it did in my transmission - either via changing the friction properties or the fluid or by plasticizing the clutch discs), but without the root cause addressed the issue is likely to repeat itself. I had this experience with AT-205 myself for my rear main seal leak - worked great for a while, then it stopped working completely, and more AT-205 did nothing other than increase oil consumption.
If the trans continues to run too hot the seals will start degrading again (likely quicker than if they were new as AT-205 isn't going to restore them to new condition) and the problem will be back in the future. Potentially a good band aid, but the trans needs to run cooler and parts that are physically damaged from the heat need to be replaced for the issue to actually be fixed.
If the trans continues to run too hot the seals will start degrading again (likely quicker than if they were new as AT-205 isn't going to restore them to new condition) and the problem will be back in the future. Potentially a good band aid, but the trans needs to run cooler and parts that are physically damaged from the heat need to be replaced for the issue to actually be fixed.
That’s my line of thinking. If I can rebuild with good results, the next move is installing a cooler and adding in a 25-30K mile transmission service or an annual 1 gallon drain and fill. We’ll see how the rebuild goes
I found with my 470 that a CSF aluminum radiator did more for trans cooling than an aux cooler. I think the integrated trans cooler within the OEM Lexus radiator is under-sized (at least on the 470), which coupled with no aux cooler (OEM 470 does have a small aux cooler) AND the thermostat/warmer gives you all some very, very hot transmissions in the 460.
Unfortunately Toyota has been going in a pattern of getting something very right (i.e., the A750F), then changing a few things and coming up with something much less reliable (760F). I'll blame CAFE regulations here but they still could have put a 30,000 mile service interval on the transmission fluid knowing how hot these were going to run.
I do agree with this. Unless the root cause is removed (too much heat) any fix we do is going to be temporary. My plan is to give the AT205 maybe a month to circulate and then change the transmission fluid to get it clean and also remove the at205, and then add a cooler or pin the thermostat open, or both. First I want to give the treatment plenty of time to soak in. My rig is at 160,000 miles today and never had the fluid changed.
As I said I’ve been doing a lot of reading in the last weeks. There is such a thing as too much plasticizer. I’m glad I listened to my AI instead of my gut and only added 1 bottle. You could make something too soft by adding too much plasticizer. @Rednexus I think in your case 1 bottle was the optimal treatment then you added a second it was too much and the seal got too soft. All conjecture on my part, but I think being conservative is a good idea also because we don’t want to dilute the transmission fluid too much. If 1 bottle works no reason to even consider adding more you are only increasing potential downsides.
Also, I wonder if Toyota WS fluid has some additive package which maintains the rubber seals but its effectiveness wears off over time. Seems like even without coolers added those who have been doing drain and fills as a maintenance program have not had the issue. Possibly just having fresh fluid maintains the seals.
As I said I’ve been doing a lot of reading in the last weeks. There is such a thing as too much plasticizer. I’m glad I listened to my AI instead of my gut and only added 1 bottle. You could make something too soft by adding too much plasticizer. @Rednexus I think in your case 1 bottle was the optimal treatment then you added a second it was too much and the seal got too soft. All conjecture on my part, but I think being conservative is a good idea also because we don’t want to dilute the transmission fluid too much. If 1 bottle works no reason to even consider adding more you are only increasing potential downsides.
Also, I wonder if Toyota WS fluid has some additive package which maintains the rubber seals but its effectiveness wears off over time. Seems like even without coolers added those who have been doing drain and fills as a maintenance program have not had the issue. Possibly just having fresh fluid maintains the seals.
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More AI reading for you guys. I asked that question and a follow up.
I am now thinking the cause isn’t too much heat. It’s just a lack of maintenance. Thank you Toyota for Lifetime Fluid… what BS!!!
Replacing the fluid every 50k miles likely would be fine without coolers added. Adding a cooler likely would buy you more time between fluid changes though.
Replacing the fluid every 50k miles likely would be fine without coolers added. Adding a cooler likely would buy you more time between fluid changes though.
Acrad
GOLD Star
IMO.. heat and maintenance
Perhaps some TC logic changes as well to allow for more slip & heat build up as well
I figure some of the real high mileage 460s probably spent most of their life out on the freeway, in lockup and reduced temps. Many of those had no maintenance at all
Owner's Service Manuals do call for severe service at 60k mile intervals but dealerships defy that with lifetime line.
It even mentions extended idling anywhere and carrying anything on the roof
Perhaps some TC logic changes as well to allow for more slip & heat build up as well
I figure some of the real high mileage 460s probably spent most of their life out on the freeway, in lockup and reduced temps. Many of those had no maintenance at all
Owner's Service Manuals do call for severe service at 60k mile intervals but dealerships defy that with lifetime line.
It even mentions extended idling anywhere and carrying anything on the roof
Getting set up
Toyota WS is IMO not good fluid. It's a low-cost, conventional fluid. I run Valvoline Maxlife ATF in mine. It's about half the cost of WS and is a full-synthetic fluid with seal conditioners in it already (which, to you point, may have a contributing factor as to why my Maxlife-AT205-Lubeguard combo had clutch slippage).
Synthetic fluids handle heat better and last longer, so the GX460 has the under-cooled trans AND a substandard OEM conventional fluid fill AND a "lifetime" change interval. A recipe for disaster. The 470 also had WS and a "lifetime" fill, but was not as under-cooled as the 460.
I will however be putting some WS in our Highlander's eCVT and rear eAWD differential. I'm not sure how Maxlife ATF will work in a planetary gearbox with copper electric motor parts, so I'll play it safe and use WS. The hybrid eCTV/eAWD fluids are also "lifetime" so changing them every 60K is probably plenty.
I just ordered the fluid for mine. I didn’t research maxlife but I like valvoline that is the motor oil I just used (full synthetic). I would probably switch to that fluid if I was doing a full drain.
I’m going to do the pan drain and fill so about 5.5changed to start and then start doing that 5.5qt change repeatedly every 30k. I’m nervous about a full drain and fill I don’t want to introduce too many variables into my experiment with AT205 right now. The fluid I ordered is this which is likely the same supplier who makes WS for Toyota is below. I won’t lie a big part of the choice was it’s only $45 for a 5qt jug so pretty cost effective too:
Btw my AI says… “Fresh fluid won’t act like the concentrated seal-conditioning additive you ran earlier. The conditioners in regular ATF are maintenance-level — enough to keep healthy seals healthy, not enough to revive hardened or shrunken ones. So fresh TLS-LV will maintain whatever the additive treatment accomplished, but if a seal starts weeping again down the road, the fluid alone won’t fix it.”
What I’m optimistically reading is that there is hope for my transmission
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MaxLife ATF was around $20-25 for a 4-quart jug but seems to have spiked to $25-30 (probably Iranian war related). It's usually the cheapest at Wal-Mart, home improvement box stores, or farm and home stores.
I'm personally a fan of a full pan-drop-and-fluid-exchange, however that is preventative maintenance on a well-functioning transmission (with a goal of having 100% new, uncontaminated fluid in the trans, or as least as close to it as possible). If you dropped the pan I suspect you would find quite a bit of crud in the bottom of it.
That is a good suggestion, maybe I’ll do the full pan drop soon. I guess depends on what I see coming out of the drain plug when I do this partial change. And couldn’t hurt to change the filter and inspect the magnets.
Idemitsu is considered to be a high quality fluid and superior to Valvoline max life for a Toyota replacement
Yes