Transmission cooler fitment

[GeeWhizz Senior Member Find all posts View Profile Close GeeWhizz]

ValeroK86,

Common practice is to run the medium to be cooled upstream of the cooling medium. That is the auto fluid flows opposite direction to the engine coolant.
If they flowed in the same direction there is minimal heat exchange, as such the higher port will be the outlet.

Interesting take on which way to arrange the plumbing. Not the way I connected mine up but I can't comment on its merit. Regardless, the bulk of the ATF cooling is done in the transmission oil cooling radiator.

The most important aspect of the plumbing is to put the extra (ATF) radiator after the main (engine coolant) radiator. The ATF temperature leaving the main radiator can never be cooler than the engine coolant, so its journey through the main radiator should only be the first stage of cooling before going to the ATF cooling radiator.

[whitewhale Lurker Find all posts View Profile Close whitewhale]

Our 2017 Prado see's the highway with a placid driver most of its life with rare offraoding/towing. I've still seen upto 110 degrees trans temp and upto 125 torque convertor temps around town. I want to help the trans last with a cooler especially when it needs to work hard but then I wonder....

-So what temperatures are people seeing after a cooler has been fitted?
-Does anyone know if the transmission has a thermostat for the oil?
If it doesn't, is the path through the radiator enough to keep the oil from getting to cool? Surely having trans oil temps below the coolant temp isn't favourable?

Thanks all

[GeeWhizz Senior Member Find all posts View Profile Close GeeWhizz]

-So what temperatures are people seeing after a cooler has been fitted? Typically 15 to 20 degrees Celcius cooler with the extra radiator. My Prado's ATF gets up to around 80C when towing a 2T camper trailer over distances in the country (Torque Converter locked in 4th gear)
-Does anyone know if the transmission has a thermostat for the oil? Pretty sure it hasn't got a thermostat.
If it doesn't, is the path through the radiator enough to keep the oil from getting to cool? Surely having trans oil temps below the coolant temp isn't favourable? I'm not clear why you think this would be a problem. Engine coolant should be typically around 80 to 90C, so would actually heat the ATF if it was cooler. When the Torque Converter is not locked, its outlet temperaure is typically 10C hotter the the pan temperature. It it's the engine temperature that you're concerned about, the engine's thermostat regulates that.

[whitewhale Lurker Find all posts View Profile Close whitewhale]

Cheers GeeWhizz for the response!

Have you ever seen below 80°? Mainly cruising without a loaded car?

Regarding my last question, not concerned about coolant temps just focusing on trans oil temps and how itl drive.
When a car is first started and not up to operating temperature, the engine/ trans will run their warm up maps (the trans will do different shift points/torque convert slip rate) to increase their fluid temps.
So if the additional cooler did to good of a job while the placid driver had control, say down to 60° pan temp, the trans could potentially run that warm up map most of the time?

[DirkZ Lurker Find all posts View Profile Close DirkZ]

Interesting conversation. I also fitted an ATF cooler from KAON two weeks ago. I initially saw on my OBD2 scan tool that my ATF temp went way up to almost 150deg when towing a smallish caravan. Then I bought the ATF cooler and found out in the mean time that I was using an older ATF version on the Scan App. I fitted the ATF cooler in any way and with the newer ATF version on the app found that the ATF temp now is about 10 deg lower than the engine temp (73-76deg). Mine was also fitted after the radiator outlet (top pipe) on my 150 shorty D4D.

[[email protected] Lurker Find all posts View Profile Close [email protected]]

Put a stock lock in and never worry about trans temp again.

[mat-with-one-t Junior Member Find all posts View Profile Close mat-with-one-t]

Just read through this thread, and here’s a nice kit and summary as to how to fit. Mat


https://www.kaon.com.au/transmission...rado-150-s~120

[DirkZ Lurker Find all posts View Profile Close DirkZ]

I installed that Kaon kit in my 2013 Shorty SX D4D a little while ago and with the help of the OBD2 bluetooth scanner has proven that it dropped my ATF temp by about 10 degrees while towing. Coming back today towing my 1800kg off-road van I found the best temps and fuel consumption was at 90kph in 4th gear. Revs at 2400RPM and speedo 90kph. ATF temp around 66 degrees and engine temp 87 deg. In Drive the ATF temp goes up to 80 and engine to 89. On slow speed steep uphill in Drive ATF temp can go even a bit higher.

[gunda Member Find all posts View Profile Close gunda]

I'd been debating fitting a transmission cooler, probably the Kaon kit, because I've seen high ATF temperatures when towing, on one occasion quite high. I have learnt how to drive so as to mostly keep it down, although it's hard to keep the temp down when towing (2.2t) up long and winding hills. And it is winter right now, presumably it will be even harder in summer.

Then yesterday I saw Anthony Fourby4 say the following on his FB group:

"Normal is anywhere near the temperature of the engine coolant since they run it through the coolant to warm it up.

The transmission needs to be up to 40° ASAP under that is not good.

And too hot is temperatures that well above what do you normally get from normal operating conditions especially when someone understands transmission operation and torque converter lock.

Under 100 is awesome up to 120 is OK but I don’t like it keep it to a minimum over 120 I really don’t like it and I’ve never seen anything like it if you’re doing that then you need to learn how to drive I can’t even get mine over 100° without trying hard in soft sand or 40° days in the high country constantly going up hills it might reach 100 to 102 momentarily as soon as you let it idle within minutes it comes back to coolant temperature

The oil can go to 150° a few times for short periods it’s not a big deal it’s only if it stays there all the time some people have their transmissions running at 120° plus too much and that’s what oxidizes oil and then it cannot protect the components."

If you accept what he says then I haven't got a problem. I can manage to keep it under 100 most of the time, and typically in the low 90s. I only saw 120 briefly once in a tough hilly tow, and I think I've learnt how to drive to prevent that.

But do you accept what he says? He is a controversial individual.

[catherder Junior Member Find all posts View Profile Close catherder]

But do you accept what he says? He is a controversial individual.

He has his followers, but I agree about this. If your ATF can stay under 100c, then you don't have an issue. However, I'm also a believer in doing a transmission service every 50k km.
Adding a cooler might be what all the cool kids are doing, but unless your circumstance warrants it, why spend the $ and add something else that can go wrong?

[Daniel150 Member Find all posts View Profile Close Daniel150]

Anthony 4b4 is usually a complete idiot who is one of those guys with a small brain spreading rubbish on the internet.
HOWEVER he is fairly correct here for once.

[Piggy Water pistol pilot. Find all posts View Profile Close Piggy]

But do you accept what he says? He is a controversial individual.

Nope. :-) And Yes, very controversial is a polite description. There are reasons he was moved on from this forum.

From one of Australia's well-known Toyota and other make transmission specialists.

"As a rule of thumb, every 15° in operating temperature above 80 degrees C. cuts the life of the fluid in half!

At 90° C., for instance, fluid life is reduced to 80,000 km.
At 110°, which is commonly encountered in many transmissions, the fluid is only good for about 60 000km.
At 120° C., the fluid won’t go much over 15,000 km.
At 135° C , and life expectancy drops to 7500kms.
Go to 150° C, and 1,000 to 2000 km is about all you’ll get before the transmission oil life is up, and we know what that can then do...."

[gunda Member Find all posts View Profile Close gunda]

At 90° C., for instance, fluid life is reduced to 80,000 km.

Reduced from what, Piggy? What's the reference temperature? I'd have said that on flat terrain when not towing and in temperate conditions, 88° was what the ATF eventually stabilises at. What's the source for those quotes?

My MY21 Kakadu is being serviced by the local Toyota dealer. What is their interval for transmission oil change?

It's always a good idea to be polite, esp on forums. I am conscious that I have a lot to learn, and the world is full of varied opinions and expertise.

[GeeWhizz Senior Member Find all posts View Profile Close GeeWhizz]

Reduced from 80,000km (to 80,000km?). The standard interval for ATF replacement is specified in your Prado's maintentence schedule book. It is wise to carry this in the vehicle for reference at all times.

[mat-with-one-t Junior Member Find all posts View Profile Close mat-with-one-t]

The standard interval for ATF replacement is specified in your Prado's maintentence schedule book. It is wise to carry this in the vehicle at all times.

Is it? I thought the manual(s) doesn’t make direct reference to particular intervals?