Preparing for a long trip and then...high trans temps...

[DenverAirport]

Without a radiator cooler in series.. I could see temps creeping while setting still.

This video helps explain the Torque convertor.
THIS Is the Most Underrated Car Invention in 2023 | The Torque Converter - YouTube

So we have 300K on a transmission and its getting hot. The TC is probably getting got warm a few times and might have the lock up section warped slightly.

If its starting to whine, quiet in natural and seems to need more beans to get it moving. The TC maybe on its way out. :-(

That's a gamble, as if the TC is bad, its possible the Transmission is going too..:-(

From what I've read the P0770 is usually a bad sign overall. It definitely needs more pump to get going, I think regardless of how the rest of the trans is doing if I need a new TC I'm going to install a different trans. If I can find a used one from someone reputable near me I may go that route, but otherwise I think I'm going to just save up and go reman.

 

[DenverAirport]

Ok, that changes things a bit. If your torque converter is not locking up then you will definitely see higher than usual temperatures. There's a driving test you can do to see if the torque converter is locking up correctly.

1. Drive around a bit until the fluid temperature starts to rise. Normally that's about 2-3 minutes of driving.
2. On a flat road that allows slow acceleration to over 50 MPH, drive from a stop and slowly increase your speed.
3. Count the number of shifts. We have a 4-speed auto with torque converter lockup so there should be 3 gear shifts and then a 4th 'shift' at 50 MPH when the torque converter locks up under light throttle. If you are under moderate or heavy throttle it will not lock up. It will also never lock up and shift below 50 MPH on stock tires and gears. Please adjust as necessary for larger tires or shorter gears.

You should be able to count the number of shifts to 4. Also once the torque converter is locked up and you apply a little bit more throttle the RPM remains flat and only increases with speed. If the torque converter is stuck in the unlocked position the RPM's will rise but speed will not rise immediately.

If the torque converter locks up as expected then the shift solenoid E needs to be replaced as it may be faulty. However the shuddering when backing up is a bad sign and there may be damage to the torque converter itself. My torque converter and planetary gears failed in my transmission last year. Some of the signs I had was increased noise as it started to whirr and then it felt like the 4Runner had dragging brakes or driving through mud. Started taking more and more throttle to keep the same speeds. It never threw a code though which means there might be hope for yours as it did throw the torque converter solenoid code.

Thanks a lot for this test. My symptoms are exactly as you describe. The increase in noise and the dragging brakes / driving through mud. Time to get out the ol' pocketbook....

 

[gamefreakgc]

Thanks a lot for this test. My symptoms are exactly as you describe. The increase in noise and the dragging brakes / driving through mud. Time to get out the ol' pocketbook....

Aw shucks, that's a real bummer. I hope you can find a good replacement as transmission parts are being discontinued by Toyota pretty fast. Maybe you can get away with just the torque converter but at that mileage if you can find a decently priced low mileage replacement transmission then I would recommend just replacing the whole deal. I got mine with 183K miles (not exactly low) but only paid $600 for it.

Car-Part.com--Used Auto Parts Market is where I got it. It's a huge database of recyclers and dismantlers.

 

[mtbtim]

Those temps you saw on that drive are totally normal when you're going up a grade in hot ambient temps at slower speeds. Overdrive off only helps with your trans temp if you're at a speed at around 40-45 mph or higher and the trans has shifted into 3rd gear. Speeds slower than 40-45 mph and the trans isn't in 3rd gear negates any benefit of turning overdrive off.

A trans cooler can only do so much. Even a pusher electric fan isn't going to make much of a difference. Those electric pusher fans actually block air flow over the cooling fins of the cooler when the fan isn't running.

The fact that you are monitoring your trans temp is good. That's more than half the battle. The key is knowing when it's prudent to pull over and give your trans a rest. The point I start considering pulling off and letting my trans cool is 230.

Steep slow speed ascents are always going to make your trans temp go sky high. The only way to avoid it is putting your transfer case in 4Lo. In 4Lo, you can climb steep grades all day and never overheat your trans. The only problem is, you can't really do this on pavement unless you have manual locking hubs like some of us do.

The amount of cooling provided by your cooler might be insufficient for driving steep mountain grades in hot ambient temps. My advice is pay close attention to your trans temp when you're climbing grades under the speed of 40-45 mph. When your trans temp gets above 230, stop, put the trans in park, and raise the rpms of the engine so the fan spins faster. Continue your drive after your trans temp has dropped below 200.

I read more closely through your thread and based off what you said, louder than normal transmission and now you're getting shuddering and throwing a P0770 code tells me your Hail Mary of dropping the pan and replacing the filter didn't work. I think you're definitely in the market for a rebuilt trans. Toyota doesn't sell them anymore unfortunately. Yota1 Performance might be able to sell you one. Yota1 Performance Engine & Machine - Your Toyota needs all in one place! Since you live not too far away from them, you could drive there to pick it up and drop yours off to satisfy the core charge. Good luck!

 

[armabill]

How are you reading the trans temps? Do you have a temp gauge or reading it a different way.

 

[brillo_76]

How are you reading the trans temps? Do you have a temp gauge or reading it a different way.

Scan gauge and 1999 and up will read temperature of transmission fluid. 96 thru 98 would have to be an aftermarket sensor. No pids have ever been found.

Sent from my SM-A536V using Tapatalk

 

[DenverAirport]

Those temps you saw on that drive are totally normal when you're going up a grade in hot ambient temps at slower speeds. Overdrive off only helps with your trans temp if you're at a speed at around 40-45 mph or higher and the trans has shifted into 3rd gear. Speeds slower than 40-45 mph and the trans isn't in 3rd gear negates any benefit of turning overdrive off.

A trans cooler can only do so much. Even a pusher electric fan isn't going to make much of a difference. Those electric pusher fans actually block air flow over the cooling fins of the cooler when the fan isn't running.

The fact that you are monitoring your trans temp is good. That's more than half the battle. The key is knowing when it's prudent to pull over and give your trans a rest. The point I start considering pulling off and letting my trans cool is 230.

Steep slow speed ascents are always going to make your trans temp go sky high. The only way to avoid it is putting your transfer case in 4Lo. In 4Lo, you can climb steep grades all day and never overheat your trans. The only problem is, you can't really do this on pavement unless you have manual locking hubs like some of us do.

The amount of cooling provided by your cooler might be insufficient for driving steep mountain grades in hot ambient temps. My advice is pay close attention to your trans temp when you're climbing grades under the speed of 40-45 mph. When your trans temp gets above 230, stop, put the trans in park, and raise the rpms of the engine so the fan spins faster. Continue your drive after your trans temp has dropped below 200.

I read more closely through your thread and based off what you said, louder than normal transmission and now you're getting shuddering and throwing a P0770 code tells me your Hail Mary of dropping the pan and replacing the filter didn't work. I think you're definitely in the market for a rebuilt trans. Toyota doesn't sell them anymore unfortunately. Yota1 Performance might be able to sell you one. Yota1 Performance Engine & Machine - Your Toyota needs all in one place! Since you live not too far away from them, you could drive there to pick it up and drop yours off to satisfy the core charge. Good luck!

This is all super helpful. I've got a line on a reman auto trans from Toyota directly for my A340F (I guess that's still possible) and I'm going to weight that option against a junkyard find. Though I may have already found one from somebody in town for 400-500. I'm looking to keep using my truck for a long time so going the reman route sounds appealing, obviously the price is a big jump but the 2-3k extra would give me great piece of mind (and hopefully an even more noticeable change in performance.)

 

[DenverAirport]

Scan gauge and 1999 and up will read temperature of transmission fluid. 96 thru 98 would have to be an aftermarket sensor. No pids have even been found.

Sent from my SM-A536V using Tapatalk

I have an ultragauge which works as well - just needed to customize settings (which only works on 99+ still obv)

 

[armabill]

I guess that you can't read the temps on a 2020.

 

[mtbtim]

This is all super helpful. I've got a line on a reman auto trans from Toyota directly for my A340F (I guess that's still possible) and I'm going to weight that option against a junkyard find. Though I may have already found one from somebody in town for 400-500. I'm looking to keep using my truck for a long time so going the reman route sounds appealing, obviously the price is a big jump but the 2-3k extra would give me great piece of mind (and hopefully an even more noticeable change in performance.)

I've got a 3 part series that will help you swap it out.

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[amalik]

Scan gauge and 1999 and up will read temperature of transmission fluid. 96 thru 98 would have to be an aftermarket sensor. No pids have ever been found.

Sent from my SM-A536V using Tapatalk

So does this also mean 96-98 can't send tranny temp via obd2?

 

[amalik]

So OP, what ended up happening with the trip, you guys had to cancel?

 

[amalik]

In 4Lo, you can climb steep grades all day and never overheat your trans. The only problem is, you can't really do this on pavement unless you have manual locking hubs like some of us do.

dang, I think I learn something new everytime I visit T4R.

So basically Tim, manual locking hub lets you utilize the "very low" transfer case 4Lo gearing (which is much lower gear ratio than using the trans' 1st gear setting I assume), but at the same time locks the front diff completely so you can avoid the whole 'binding on dry pavement' issue of part-time 4WD?

 

[Bad Luck]

Thermostat DELETE


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There's no thermostat for the transmission fluid cooling system.

 

[Bad Luck]

dang, I think I learn something new everytime I visit T4R.

So basically Tim, manual locking hub lets you utilize the "very low" transfer case 4Lo gearing (which is much lower gear ratio than using the trans' 1st gear setting I assume), but at the same time locks the front diff completely so you can avoid the whole 'binding on dry pavement' issue of part-time 4WD?

You're very close. Manual hubs would allow you to put the transfer case into 4LO without the driveline binding up. With the front hubs unlocked there will be no power transfer to the front wheels and no way for it to bind up on dry surfaces.

Alternatively to manual hubs you can modify a j shift transfer case to twin stick so you can use low range while in 2wd. You can also modify the wiring on a j shift transfer case vehicle to not allow the front ADD actuator to engage also giving you an unlocked front axle similar to manual hubs.

 

[mtbtim]

dang, I think I learn something new everytime I visit T4R.

So basically Tim, manual locking hub lets you utilize the "very low" transfer case 4Lo gearing (which is much lower gear ratio than using the trans' 1st gear setting I assume), but at the same time locks the front diff completely so you can avoid the whole 'binding on dry pavement' issue of part-time 4WD?

Yeah, what [MENTION=319302]Bad Luck[/MENTION] said.

And Yes, you can't read your tranny temp on a 96-98 via the OBDII port. You have to install an aftermarket transmission temp gauge like I did in the video below.


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[Bad Luck]

I'm running a Koyorad and a B&M 70268. I recently did a trans drain and fill and filter replacement (at 300k, which was 2k miles ago). The majority of my driving since the drain and fill has been 100 above outdoor temp. If I'm going through mountains I turn off O/D and I rarely see above 200 even on super hot days.

The cooler you have now is 13k btu rated. On my automatic 4Runner I used a TruCool LPD4589 which is rated for 21k btu and has an integral thermostat to help the transmission fluid get up to temperature. I didn't drive in the mountains with it, but I never saw above 180*F under any condition including offroading or pulling a trailer through the hill country. I'd recommend it to anyone looking to bypass their radiator for transmission fluid cooling.

 

[amalik]

You're very close. Manual hubs would allow you to put the transfer case into 4LO without the driveline binding up.

So isn't this accomplished by locking the front differential? Maybe I'm missing something.

Or this is a lock/unlock feature on the individual CV axles in the front 2 wheels?

 

[Bad Luck]

So isn't this accomplished by locking the front differential? Maybe I'm missing something.

Or this is a lock/unlock feature on the individual CV axles in the front 2 wheels?

Manual hubs are located on the steering knuckle/spindle. With the hubs unlocked the outer portion of the hub that the rotor/wheel attaches to spins freely from the inner part of the hub that the axle shaft is attached to. With the hubs unlocked you won't have any transfer of power to the front wheel regardless of 2wd or 4wd transfer case selection. Manual hubs do not interact with the front differential in any way.

 

[gamefreakgc]

This is all super helpful. I've got a line on a reman auto trans from Toyota directly for my A340F (I guess that's still possible) and I'm going to weight that option against a junkyard find. Though I may have already found one from somebody in town for 400-500. I'm looking to keep using my truck for a long time so going the reman route sounds appealing, obviously the price is a big jump but the 2-3k extra would give me great piece of mind (and hopefully an even more noticeable change in performance.)

Our 4Runners reputation of being bulletproof is starting to get tested as everything other than the engine starts to break (or in my case I broke the engine too). Financial status also plays into this as nobody want to pay for a repair like that on a credit card or loan.

My only comment on used transmissions is there is no real way to verify the mileage. Unlike an engine, there's no compression test to be done and dropping the pan only shows extreme neglect and would be easy to hide by just cleaning it before hand. I do not know how helpful it is but I don't buy from sellers, both private or commercial, that round their reported mileage. If they are too lazy to put a real mileage on the vehicle they removed it from I do not trust them enough to buy it. Hope that helps in your search.