Transmission temps towing with a 3rd gen Tacoma

For those of you with a deeper knowledge of towing and transmission temps, I’d appreciate your perspective. I’ve read a lot on this forum but wanted to talk this through for a newer truck.


I’m driving a 2018 Tacoma TRD Sport with tow package. I’m towing around 4k lbs. and having no real difficulty with the set up (brake controller, WDH, keeping things in S with ECT on).


Towing in the mountains, 30-50mph on steep/winding roads, normal is 201 at the pan and I’m seeing high temps as high as 205 at the pan and 210 at the converter. Staying in 2nd and 3rd mostly.


Towing in the plains, 55-70mph on long grades with some head winds, normal is 205 at the pan and I’m seeing temps as high as 215 at the pan and 240 at the converter. Cruising in 3rd up hill and 4th on downhills.


When not towing I’m seeing stable 195 temps with spikes up to 205 at the pan and 210 at the converter when passing, heading up hill, or letting the darn thing shift all over the place.


My near-term plans involve moderate towing in the mountains and several cross-country trips.


So, given that, my questions are:

1. Are these towing temps high enough to be concerning or are they what I should be expecting while managing the transmission temp (i.e. slowing down or taking breaks to keep it in this range)? Is running at 205 and spiking to 215 at the pan for three straight days going to bite me on a trip?
   
   
2. Should I be paying attention to the converter temps at all (they seem to have a very wide range and change quickly)?
   
   
3. Is it worth tossing away the warranty to install an after-market transmission cooler?
   
   
4. If so, when I’m installing the cooler:
   1. What is the recommended procedure to make sure I’ve got the right fluid levels with the new cooler installed?
      
      
   2. Any good sources for a step by step on this procedure?
      
      
5. Is it better to put the larger cooler in line after the stock trans cooler or to replace the stock trans cooler all together?
   
   
6. Given my plans for towing, should I be using different transmission fluid and/or changing it more frequently?

Thanks for your help -

 

I don’t think that you’d be affecting your warranty if you do a proper install of a larger, non stock transmission fluid cooler.
A transmission cooler replacement can obviously assist in keeping your transmission from overheating and causing damage due to excessive fluid temperatures.

A damaged transmission would require a trip for service and repair.
Stay away from the dealer. Why not just replace the stock cooler with something bigger and better?
No more worries about excessive temps from towing or crawling.

If you purchase an aftermarket cooler, I’d recommend a Tru Cool cooler made by Long Manufacturing.
Long Mfg. also makes B&M coolers which are exactly the same as Tru Cool, but just more expensive.
I learned that by previously purchasing both.

The stacked plate coolers, with no delicate fins to bend, are a little more stout than the tube and fin or plate and fin coolers, and the largest cooler (#4590) they make will fit in the stock location on the Tacoma.

Add a quart of fluid to the cold transmission.
Pin the thermostat open, warm the transmission up a bit, close to within the proper temperature range.
Drain the excess fluid from the overflow plug (not the drain plug!) at the pan.

There are many pages to be found regarding the procedure explained at length.

 

Those temps are nominal. No worries.

 

A new rabbit hole to explore!

 

@OregontoBajaCA - thanks for your post. Detail is awesome and appreciated.

Sigh... I'm hoping you are right about this. The service department at the local dealer disagrees, but I think that's part of their training...

Really appreciate the recommendation.

Will keep looking for one.

 

Appreciate the confirmation @hiPSI

 

So replace the stock cooler or just add this in line? Before or after stock if inline?

 

I’d just replace it if you want more cooling capability. You could also install it after.

You’ll find that people do it any of the three ways you mention.

As the OPs temperatures are not too high, adding to the cooling capabilities may only help to keep one from worrying about overheating in case one happens to encounter extreme ambient temperatures while towing and/or carrying heavy loads over extreme terrain.

 

Transmission health and longevity is all about fluid temperature (no surprise)... the below chart provides a guide to potential damage concerns based on continuous operation at the indicated temp. BTW, 240 is too high of a sustained temp... change the fluid soon as you have reached the temp at which the seals begin to harden.

 

I’ve gotten to 220 pan and 285 converter temps. Didn’t smell burnt but was a bit brown. MaxLife transmission fluid is cheap enough at ~$17 a gallon @ Walmart. I do a annual drain and fill, its easy enough.

After 45k miles.

 

"One" does tend to worry about such things...

 

Yes, perhaps, some do.

In general, for many, there may be more important things in life to be worried about than car stuff.

 

Nice, very clean install. I added a cooler like yours to my old truck but instead of removing the stock one, I just spliced into one cooler line, added the aftermarket cooler and then continued the line into the stock cooler. Kind of a two-for-one deal. I’ve always been told by tranny guys that too much heat is an automatic transmissions worst enemy so.......
**If anyone is worried about winter and running with too low oil temps, there are also large coolers available with a thermostat/bypass that only opens when warmed up.

 

Nice picture on the bike Dave!

The Tacoma transmission has a thermostat, so no worries about over cooling. Also, the internal bypass of the stacked plate cooler supposedly doesn’t allow as much cooling of thicker, colder fluid until that fluid is warmed by the transmission.

People in warmer climates sometimes just keep the thermostat pinned open with a nail or small clip.

I’ve read many times that you can’t over cool a transmission, but perhaps those living in the northern States and Canada have a different experience with extremely cold sub zero temperatures and automatic transmission shifting.

In my experience with operating a vehicle in ambient temperatures just above zero degrees, I’ve never had an automatic transmission fail to shift properly when starting off cold.