Radiator, Trans. Cooler, or both....

[amalik]

Yes, I'm pretty sure it helps even at slower speeds. The reason why I say so is I've tested it climbing mountain roads and I'm nowhere close to the transmission shifting into the overdrive gear and I've seen my trans temps drop as soon as I switched off overdrive. When I know I'm going to be climbing a grade, it's a fairly sustained climb (not a short hill), and I'm not exceeding 65mph, I'll turn my OD off.

I could be talking out of my ass here in regards to the slower speeds because I could be remembering incorrectly and I was driving at the speed where the transmission was in between 3rd gear and overdrive and turning off overdrive kept the transmission from constantly downshifting and up shifting back and forth from 3rd and 4th(overdrive) gears.

Just try it out and see what I'm talking about. Btw, I didn't discover this trick. I read it on the this forum sometime in the past and it was explained that turning overdrive off locks up the torque converter. I'm not a automatic transmission expert so I took their word for it.

I think in the very near future, I'll take a drive up a mountain road in the Santa Cruz mountains and video the temp change as soon as I switch off the overdrive.

I feel you. Whenever I'm going up a mountain hill, I turn O/D off.

I think the auto tranny and the TC lock at a certain RPM/speed range even when O/D is on.

 

[Co4Fun]

Well, I was talking out of my ass at some level. Turning OD off does nothing to reduce your trans temps if you're going at a slower speed. I tested it out this morning climbing a mountain road and confirmed it.



However, when you're at a speed in-between 3rd gear and 4th gear (overdrive) where the trans keeps on downshifting and upshifting between the two gears, turning off overdrive definitely reduces your trans temps. When you're have OD on and you're climbing a grade that doesn't allow you to be cruising in the OD gear, the transmission will kick down to 3rd gear when you give enough throttle response to maintain your speed. When that downshift occurs, your trans temps will start to climb. If you turn the OD off in this situation, you'll see an immediate drop in temperature.



I documented this via video so I'll do a some quick Timmy the Toolman editing and post it here so Y'all can see what I'm talking about.

So I think you have nailed it! This makes sense and also your description of how OD works. For all intensive purposes we can talk about it as 4th gear.

Turning it off holds you in 3rd allowing higher RPM which is handy depending on the many variables in any climbing/towing situation to keep the tranny from trying to shift back and forth a lot between 3rd and 4th and to keep it from trying to "lug" too much in 4th with too low of RPM's for the given situation.

And, it's also handy for downhill to be able to keep it in third with higher RPM's and the engine holding it back so as not to use the brakes so much.

One final comment...another guy mentioned ECT button. That is not the same as what OD does that we've been discussing. Tons of threads on that. ECT changes the shift points so that it will shift at higher RPM's and allow it to wrap up more. This helps a lot towing so as not to struggle so much accelerating and to shift more of the burden to the engine and less on the tranny to a degree. I have played with it and it does work and is fun going up the passes. But...keep it the ECT in and your foot in it and get ready to stop at the next gas station. But it is kind of fun!

But I don't know...does ECT also disable OD/4th when pressed? Hmmm? I'll have to play.

 

[mtbtim]

Ok, here's my short little video showing how turning overdrive off will lower your trans temps in certain situations:

<iframe width="560" height="315" src="https://www.youtube.com/embed/BEZfDOkGVno" frameborder="0" allowfullscreen></iframe>

 

[johnbyebye]

Just to add to this discussion:

It is my understanding that the clutch is not activated by button but rather activated dependent upon the amount of power the torque converter is receiving from the engine as well as the flow of fluid. When the speed of the turbine reaches a similar speed to that of the stator, the clutch is applied. This can happen outside of overdrive as well in any situation when force is not being applied to or is equal to the torque converter's output. In overdrive the gear ratio is essentially 1:1 so the clutch would be applied. As soon as a downshift occurs, the clutch is released due to a change in the flow of the transmission fluid.

Man this stuff can get confusing.

 

[geocook717]

regarding the pink milkshake issue with 3rd gens. If a rig has already had a pink milkshake (all steps were taken to reduce damage and all parts replaced), is that rig any more susceptible to another milkshake versus a rig that may not have had a pink milkshake in the past?

 

[mtbtim]

regarding the pink milkshake issue with 3rd gens. If a rig has already had a pink milkshake (all steps were taken to reduce damage and all parts replaced), is that rig any more susceptible to another milkshake versus a rig that may not have had a pink milkshake in the past?

No, your rig is not any more susceptible to another pink milkshake.

The way the pink milkshake occurs is the stock trans cooler in the bottom of the radiator has a structural failure. The compromised cooler allows engine coolant to mix with the automatic transmission fluid and that contaminated mix makes it's way back to the transmission causing the transmission to slip and eventually fail.

So, we're only talking about one component failing causing this and that's why some 3rd Gen owners chose to replace the radiator as preventative maintenance. Your vehicle has the same chance as anyone else's to have this happen.

What people have to realize is since we frequent forums like this, the pink milkshake issue with 3rd Gen 4runners seems a lot worse than it really is. It's the same with the lower balljoints. Toyota made a ton of these 3rd Gens, somewhere in the area of 600,000 and I see them all over the road everyday. Most of these owners aren't on forums like this and are oblivious to the pink milkshake and lower balljoint problems and drive them to high mileages without any problems. I talked with a long time service advisor at my local Toyota dealership and he couldn't remember one 3rd Gen coming in with a trans cooler failure causing a transmission issue. I talked with another mechanic with 30+ years of experience and he never heard of it happening on a Toyota but he's seen it in domestic vehicles.

So, you were one of the unlucky ones experiencing this failure and you probably have a better chance being struck by lightning than experiencing this problem again on your 3rd Gen.

 

[tvpierce]

As I understand it (at least in the '01 & '02 electronically controlled trannies), the TC locks at 48mph in 4th gear, and 42mph in 3rd gear with the OD turned off.

 

[geocook717]

Thanks mtbtim. Thankfully, it wasn't me that experienced the pink milkshake, it was however my rig with the previous owner. Thankfully he took rather exceptional care of the vehicle, it just goes to show support in your statement above. Go figure the extremely detail oriented car owner is the one to experience that mess. He, and consequently I, seemed to have dodged a bullet in the grand scheme. It was over a year ago and pry 12,00 miles, the rig is still running and seems primed to hit 200k and beyond. I love it

 

[19963.4lsr5]

As I understand it (at least in the '01 & '02 electronically controlled trannies), the TC locks at 48mph in 4th gear, and 42mph in 3rd gear with the OD turned off.

That's my 97 also.


Sent from my iPhone using Tapatalk

 

[19963.4lsr5]

When I took the first 4Runner (96 SR5) to get inspected he said to watch the trans fluid for the pink milk shake. If I catch it before the trans starts slipping I'm good. He said Nissans do it too. My neighbors big Nissan SUV had the pink milkshake at only 5 years old.


Sent from my iPhone using Tapatalk

 

[jtnumberthree]

This has been my experience as well.

 

[tarsun]

you would have top buy one for a manual trans 4runner.

also you want the trans fluid to get warm, just not boiling. it will shift like sh*t when its cold. (this has been my experience)

get a new rad and install the remote cooler at the exit of the rad trans cooler.
this way, it warms it up, but keeps it cool.

NOTE: while we might not all agree on the/my placement of the remote trans cooler, we will/should all agree to get a new radiator regardless.

 

[SaulG]

No sense in building two different radiators ,every one comes with a cooler

 

[cblock406]

Replace the radiator as preventative maintenance. The potential for a pink milkshake is one thing but you could also just spring a leak or the plastic top could dramatically crack from age and leave you stranded somewhere. With the mileage you have, it's a good idea.

Even with normal driving, no crazy 4wheeling or towing, your trans temps can get pretty high. All you have to do is drive some extended mountain roads and you'll easily see temps around 230.

In my opinion, adding a trans cooler and running it in-series with the radiator cooler is the way to go.

Also, don't forget to turn overdrive off when you're climbing grades and going around 65mph or less. Turning off overdrive locks up the torque converter and will drop your trans temps by 20+ degrees.

Here's a video I made installing a new radiator, thermostat and an external trans cooler in my rig:

<iframe width="560" height="315" src="https://www.youtube.com/embed/2nVbwe2t2T8" frameborder="0" allowfullscreen></iframe>

Sorry to bump an old thread but have a quick question: It looks like you installed the cooler after the coolant goes through the radiator cooler. Is there any logic to install it either before or after the transmission cooler, or would it even matter?

I'm going to do mine soon and in my head I kept picturing installing before is the only reason I ask.

Thanks!

 

[19963.4lsr5]

Factory my Cummins is aux cooler and then the coolant cooler (rad cooler). But I guess depending on your climate aka live where it's hot put cooler after rad. Cold climate put cooler before rad.


Sent from my iPhone using Tapatalk

 

[mtbtim]

Sorry to bump an old thread but have a quick question: It looks like you installed the cooler after the coolant goes through the radiator cooler. Is there any logic to install it either before or after the transmission cooler, or would it even matter?

I'm going to do mine soon and in my head I kept picturing installing before is the only reason I ask.

Thanks!

What was said above is correct. In colder climates, people opt to have the ATF go through the radiator cooler last because it will warm it before returning to the transmission. But, many auxiliary coolers, like the B&M one I bought, have a thermal bypass. When the fluid is cold and thicker, it won't travel down the smaller cooling channels and just travel straight though. When the fluid gets hotter and thinner, it will then travel though the cooling channels for additional cooling. So, I don't know if even in colder climates it's necessary to have the fluid go through the radiator cooler last.

 

[cblock406]

Factory my Cummins is aux cooler and then the coolant cooler (rad cooler). But I guess depending on your climate aka live where it's hot put cooler after rad. Cold climate put cooler before rad.


Sent from my iPhone using Tapatalk

What was said above is correct. In colder climates, people opt to have the ATF go through the radiator cooler last because it will warm it before returning to the transmission. But, many auxiliary coolers, like the B&M one I bought, have a thermal bypass. When the fluid is cold and thicker, it won't travel down the smaller cooling channels and just travel straight though. When the fluid gets hotter and thinner, it will then travel though the cooling channels for additional cooling. So, I don't know if even in colder climates it's necessary to have the fluid go through the radiator cooler last.

Gotcha, that makes sense. Thanks for the response guys!