Towing - Aux Fan for Stock Transmission Cooler

[Mindflex]

There is a lot out there about after market transmission coolers.

However curious if anyone has done or is aware of a way to install an additional fan over where the area of the stock radiator that has the transmission fluid run through it.

I cannot find a picture but believe the portion of the radiator that cools the transmission fluid is on lower left of the radiator (when looking at it from the front).

Thinking by adding a fan there it will help cool the transmission a little better.

I am reluctant to install a transmission cooler as it creates another point of failure and could void the warranty. I also read that in certain cases (low speed, high resistance driving such as towing in traffic or off roading) the after market cooler can sometimes be worse.

I plan to tow about 4K pounds total a few times a summer anywhere from 10 to 150 miles each time.

I have rear air bags installed as well.

I know opinions range from 'stock setup will pull 7k pounds up hills with no wear' to 'you need a trans cooler bags, wds etc for 2k pounds'.

I am looking to get a little extra cooling without voiding my warranty or adding failure points.

Thoughts on how to do this?

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[wfo9]

It won't do any good at all IMHO. In fact, you will probably just restrict airflow.

 

[WallyT4R]

Yes the info here is vague on transmission coolers but there are a few write ups. Just search 5th gen transmission cooler on Google. I have not heard of the issues you mention. From the research I have done people have seen much lower trans temps following the install.

I bought an auxiliary transmission cooler. I have not installed it yet but I will plumb it to be after the factory cooler that is built into the radiator. I might have the dealer install it to avoid warranty bs even though it's a pretty simple mod.

I bought this one through Summit. It's seems to be very well built. The only thing I would change is I should have bought the 11"x10" but this one will be adequate enough. After I bought it I heard you should try and get the biggest one possible since you cannot "over cool" transmission fluid.

I also bought this to mount it.. This will put my mind at ease while towing even though others say it is not necessary. :beer:

EDIT: You don't mention it but with as much weight as you plan to tow you should add a brake controller if you don't already have one. I have a Prodigy 3 mounted on the lower dash to the left of the air bag. Works great.

 

[(none)]

the stock (in the radiator) oil to water cooler runs along the bottom (the coolest part) of the radiator. The mechanical fan is always spinning, pulling some air through the radiator. There would be no advantage to adding an electric pusher fan down there to help cool the transmission fluid.

Just add a 2nd (oil to air) cooler and be done with it. As long as you don't screw anything up with install, it won't void your warranty (have a dealer install it if you're that worried), and there is no way it could cause your transmission to run any warmer than with just the one cooler.

Currently, with my setup, my trans runs around 135-145F during normal driving. Long, high speed trips, I may reach 150F. Even towing (a bit over 5k lbs with a CRV on a car hauler), I only got to around 180-185 and that was during slow speeds, lots of throttle while moving through town (TC unlocked). All temps are much lower than stock and with having the mechanical fan, there is always at least some air being pulled through the cooler.

Granted, I'm in south Georgia, but even on "cool" mornings (30-40F), the trans still warms up quickly, I think the TC will start to lock once the trans reaches around 90-100F, which it has no problems maintaining since I still have the cooler (would be more of a heater in this case) in the radiator.

This is the setup most trucks with tow packages run, the V8 4runners ran this setup, etc, albeit they run much smaller 2nd coolers.

 

[1engineer]

There is a lot out there about after market transmission coolers.

However curious if anyone has done or is aware of a way to install an additional fan over where the area of the stock radiator that has the transmission fluid run through it.

I cannot find a picture but believe the portion of the radiator that cools the transmission fluid is on lower left of the radiator (when looking at it from the front).

Thinking by adding a fan there it will help cool the transmission a little better.

I am reluctant to install a transmission cooler as it creates another point of failure and could void the warranty. I also read that in certain cases (low speed, high resistance driving such as towing in traffic or off roading) the after market cooler can sometimes be worse.

I plan to tow about 4K pounds total a few times a summer anywhere from 10 to 150 miles each time.

I have rear air bags installed as well.

I know opinions range from 'stock setup will pull 7k pounds up hills with no wear' to 'you need a trans cooler bags, wds etc for 2k pounds'.

I am looking to get a little extra cooling without voiding my warranty or adding failure points.

Thoughts on how to do this?

Sent from my Moto G4 Plus using Tapatalk

[MENTION=133557]Mindflex[/MENTION] let me give you a bit of theory before you decide:

I have done countless water/oil and air/oil heat exchanger (what you call a radiator or a transmission cooler) calculations in my job and there is some basic knowledge you are missing here.
There are a series of calculations and tests that Toyota has done before they decided to install your radiator and trans cooler. They didn't just go "hey, we have that one in the parts bin, let's stick it in and see if it works." They calculated potential heat load, surface area, wind speed, ambient temperatures, delta T's and a whole host of other things engineers do for fun. What they came up with is what you have in your vehicle. They know what they are doing. They didn't mess up. As a matter of fact, if you had access to one of their cell phone numbers you could be towing up a 7% hill in Colorado on a 90 degree day at 9,300 feet, call them with your data and they could tell you within a few degrees what all your temperatures are. Seriously.

My whole point of this is, believe it or not, air flow! Did you know that too much air flow through a heat exchanger is just as bad as too little air flow? Why? Fluid (oil or water, does not matter for this explanation) enters the heat exchanger at a temperature. It remains in that heat exchanger for a precise time and then exits the heat exchanger at a reduced temperature. The change in temperature of incoming/outgoing fluid is determined by the material type, surface area, ambient air temp and, for this discussion, wind speed. Toyota has this calculated and tested in all situations. You, by adding this fan, could speed up air flow in some situations like stop and go traffic, or SLOW DOWN air flow when traveling 70 mph on the interstate. Those two might cancel, or they might not and you could actually increase the temperature by adding the fan! Adding an aux cooler usually does not hurt much. It does not help much either unfortunately but to each their own.

Toyota knows what they are doing. I have towed 5K quite a few times in both hot and cold temps with no problems. They designed the 4Runner to do this without any additional add ons. If I were you I would think twice and do several tests if you are going to add an additional fan. Just because you get more air flow in some situations does not mean you get more in all conditions.
Good Luck!

 

[Mindflex]

[MENTION=133557]Mindflex[/MENTION] let me give you a bit of theory before you decide:

I have done countless water/oil and air/oil heat exchanger (what you call a radiator or a transmission cooler) calculations in my job and there is some basic knowledge you are missing here.
There are a series of calculations and tests that Toyota has done before they decided to install your radiator and trans cooler. They didn't just go "hey, we have that one in the parts bin, let's stick it in and see if it works." They calculated potential heat load, surface area, wind speed, ambient temperatures, delta T's and a whole host of other things engineers do for fun. What they came up with is what you have in your vehicle. They know what they are doing. They didn't mess up. As a matter of fact, if you had access to one of their cell phone numbers you could be towing up a 7% hill in Colorado on a 90 degree day at 9,300 feet, call them with your data and they could tell you within a few degrees what all your temperatures are. Seriously.

My whole point of this is, believe it or not, air flow! Did you know that too much air flow through a heat exchanger is just as bad as too little air flow? Why? Fluid (oil or water, does not matter for this explanation) enters the heat exchanger at a temperature. It remains in that heat exchanger for a precise time and then exits the heat exchanger at a reduced temperature. The change in temperature of incoming/outgoing fluid is determined by the material type, surface area, ambient air temp and, for this discussion, wind speed. Toyota has this calculated and tested in all situations. You, by adding this fan, could speed up air flow in some situations like stop and go traffic, or SLOW DOWN air flow when traveling 70 mph on the interstate. Those two might cancel, or they might not and you could actually increase the temperature by adding the fan! Adding an aux cooler usually does not hurt much. It does not help much either unfortunately but to each their own.

Toyota knows what they are doing. I have towed 5K quite a few times in both hot and cold temps with no problems. They designed the 4Runner to do this without any additional add ons. If I were you I would think twice and do several tests if you are going to add an additional fan. Just because you get more air flow in some situations does not mean you get more in all conditions.
Good Luck!

Thank you, this is good insight. Agree that this approach doesn't make the most sense.

Appreciate the response.

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[Mindflex]

Yes the info here is vague on transmission coolers but there are a few write ups. Just search 5th gen transmission cooler on Google. I have not heard of the issues you mention. From the research I have done people have seen much lower trans temps following the install.

I bought an auxiliary transmission cooler. I have not installed it yet but I will plumb it to be after the factory cooler that is built into the radiator. I might have the dealer install it to avoid warranty bs even though it's a pretty simple mod.

I bought this one through Summit. It's seems to be very well built. The only thing I would change is I should have bought the 11"x10" but this one will be adequate enough. After I bought it I heard you should try and get the biggest one possible since you cannot "over cool" transmission fluid.

I also bought this to mount it.. This will put my mind at ease while towing even though others say it is not necessary. [emoji481]

EDIT: You don't mention it but with as much weight as you plan to tow you should add a brake controller if you don't already have one. I have a Prodigy 3 mounted on the lower dash to the left of the air bag. Works great.

Thank you for this good info! My tailer does have breaks and is dual axle.

I think I will go with your advice and have the dealer install so the risk is all on them.

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[WallyT4R]

Ok so finally spoke with the dealer about installing the trans cooler. They refused to do it because they said it would void the warranty....:crutch:......so...I have decided to not put it on. I will try and return the cooler and mounting kit...ridiculous! Lawyer BS :tape:

 

[(none)]

Ok so finally spoke with the dealer about installing the trans cooler. They refused to do it because they said it would void the warranty....:crutch:......so...I have decided to not put it on. I will try and return the cooler and mounting kit...ridiculous! Lawyer BS :tape:

They just don't want to screw with it. Just mount one yourself or have an independent shop do it. Just gotta make sure you top up the trans fluid.

 

[WallyT4R]

They just don't want to screw with it. Just mount one yourself or have an independent shop do it. Just gotta make sure you top up the trans fluid.

Yeah I can install it easily as I have done it several times on other vehicles. The problem is the voiding of the warranty. The other problem is to check the fluid level on these things is a complete pain in the butt. Trans has to be a certain temp so need a temp gauge, open the check valve, add fluid, get the trans back up to temp, open the check valve...repeat as necessary...pain in the butt!

I guess I am just going to take my chances and let it ride as is for now. Time will tell if it needs a cooler or not. I'm also going to add my scan gauge to it and keep an eye on the temps. If the temp is consistently in the 200's the cooler is going on no matter what about the warranty.

 

[Mindflex]

Yeah I can install it easily as I have done it several times on other vehicles. The problem is the voiding of the warranty. The other problem is to check the fluid level on these things is a complete pain in the butt. Trans has to be a certain temp so need a temp gauge, open the check valve, add fluid, get the trans back up to temp, open the check valve...repeat as necessary...pain in the butt!

I guess I am just going to take my chances and let it ride as is for now. Time will tell if it needs a cooler or not. I'm also going to add my scan gauge to it and keep an eye on the temps. If the temp is consistently in the 200's the cooler is going on no matter what about the warranty.

After further research and contacting 2 Toyota dealerships I am in the same boat.

Not willing to void my warranty and while I will keep my truck for awhile, will sell before any wear related issues come up past the 150K mark.

Really unfortunate that Toyota puts us in a situation or having to choose between voiding the warranty or putting extra wear on the transmission even within the approved towing specs of 5k pounds. [emoji35]

Have a OBD2 adapter and phone app to keep an eye on temps.

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[(none)]

After further research and contacting 2 Toyota dealerships I am in the same boat.

Not willing to void my warranty and while I will keep my truck for awhile, will sell before any wear related issues come up past the 150K mark.

Really unfortunate that Toyota puts us in a situation or having to choose between voiding the warranty or putting extra wear on the transmission even within the approved towing specs of 5k pounds. [emoji35]

Have a OBD2 adapter and phone app to keep an eye on temps.

Sent from my Moto G4 Plus using Tapatalk

I'm still trying to figure out how a cooler is going to void your warranty...

yes, if the cooler were to fail which caused damage to your transmission, that would be true. But just to blindly state that because you have a transmission cooler installed, you have no warranty doesn't make sense. I still stand by they don't want to screw with it. They don't want to install someone else's parts then be held on the hook for it. Do it yourself and roll on. No one here has ever reported an issue after they've installed one from what I've read and searched.

 

[Mindflex]

I'm still trying to figure out how a cooler is going to void your warranty...

yes, if the cooler were to fail which caused damage to your transmission, that would be true. But just to blindly state that because you have a transmission cooler installed, you have no warranty doesn't make sense. I still stand by they don't want to screw with it. They don't want to install someone else's parts then be held on the hook for it. Do it yourself and roll on. No one here has ever reported an issue after they've installed one from what I've read and searched.

You are correct and that is what I was referring to - the warranty for the transmission.

My fear is that the transmission could fail on its own (very unlikely but still possible) and they blame the transmission cooler even if it had nothing to do with it. (Void warranty)

I read of someone that happened too. Obviously very unlikely situation but expensive if it happens.

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