Transmission temperatures

Thanks for the assist!

 

Using an OBD reader and the codes listed on the first page of this thread I'm able to read my tranny and torque converter temps. Usually they're around 175 for the tranny, and the same/ higher for the TC. I've seen my tranny hit 195 degrees! Is this normal in 100 or so degree ambient temps?

 

What I have read was your temps should only be 100 degrees above outside temp, towing a bit more and try to keep it under 220 so your's sounds about right. Mine does not do that, averages 131 in 75 degree weather, but we are heading out on a long trip towing a trailer in the desert, climbing one heck of a winding mountain at the end and will be reporting back. I have adjusted my cam to get the scan gauge in view so I don't have to drive and watch it, just glance and have the copilot monitor it. It records for 12 hours so I will review it in the evenings.

 

My trans (tc) temp was about 180 or so most of the day...it got to 200 at a steep incline.

85 degrees out

 

Got mine dialed in. I was missing a Zero on the MTH# Thanks again everyone!

 

Kewl, I was surprised with my eyesight that I got mine right the first time. But I have been dealing with Binary and Hex for 50 years. Let us know what your reading range is.

 

I recently installed a scangauge 2 because I am soon going to be regularly towing a 3500 lb trailer and I wanted to monitor my trans fluid temps before I got the trailer.
At highway speeds of 65-80 the fluid holds very steady at 190-195 at both the pan and the torque converter.
Ambient temp is 80-90 in TX right now.
That 190-195 is without towing anything (4.88 gears, 33" tires).
With these temps holding steady, I installed a Hayden trans fluid cooler and ran it in tandem with the stock cooler.

Result - My trans fluid temp is exactly the same as before the cooler was installed - 190-195. No change.

The Hayden cooler is installed correctly and an additional 1/2 quart of ATF was added with the thermostat pin depressed.
The new cooler is slightly warm after a drive so I know fluid is circulating through it.

Anyone have any ideas or experienced similar? I was sure the temp would drop at least 5-10 degrees.

 

I added the Hayden heavy duty trans coolr in line/tandem, did the flush, and went ahead and installed an old motorcycle fan in there via a switch, and temps without fan are usually 175 and lower... 145 and lower with the fan...
Where is the location of your cooler?? Are your trans lines linked, or creased??

 

This is how the two coolers are connected:
No kinks, no creases, no leaks.


This is the steady temperature I get with the Hayden cooler installed and the thermostat NOT pinned.


Scenario after Hayden cooler install:

I was driving last night at highway speeds for over 20 minutes with ambient temperature at 72 degrees. The trans temp fluctuated from 190 to 195.

I was driving today at highway speeds for over 20 minutes with ambient temperature at 90 degrees. The trans temp fluctuated from 194 to 199.

For an empty truck with no tow weight that is easily 10-20 degrees higher than normal considering fluid should be between 75-100 max degrees above ambient temperature.

I stuck the pin back in the thermostat and drove it like that - the temps fluctuated between 162 and 177 which is the proper temperature range. I watched the temps go down when I was at steady higher speed due to wind force on the coolers. This is how it is supposed to run.

I did not think I was supposed to leave the thermostat pinned but to achieve the temperatures that are ideal (and normal) I will have to, especially when I start towing my trailer.

Transmission fluid is and has been at normal operating level. I just rechecked it today.

 

The Hayden is a decent unit, your temps should be 20+degrees cooler.

I would double check your return, it should go from the Hayden to your trans.

Also, you might have an air bubble in the Hayden due to your orientation. Try mounting it horizontal with the in flow on the bottom.

If that doesn’t work, pull the stock cooler and just run the Hayden.

 

What is this thermostat pin? Did the Hayden come with a thermostat or something?

 

All Tacomas with a tow package have a trans fluid thermostat located to the front of the trans fluid pan.
No tow package, no thermostat.

 

Apparently 195 is normal operating temp for gen 3 Tacomas. The thermostat kicks open when above 195/200 and allows fluid to pass through the coolers. Slightly accelerated fluid breakdown occurs after 200 F (much faster breakdown occurs after 225).
In Texas it's frequently 100 F (still in the 90's in late September). Too hot for a trans to be steadily running at 195. By pinning the transmission thermostat open, my steady trans fluid temps are 160-180 instead of 195.
With normal operation without a pinned thermostat, with the trans temp regularly at 195, I don't see how the fluid could safely make it 100k miles as Toyota states is the norm.
I'd rather err on the side of caution and keep the temp lower.

If/When I travel to colder locales where the ambient temp is regularly below 40, I'll most likely remove the pin.

 

Maybe this is a 3rd gen thing? Just saw some pictures of what you are talking about on a 3rd gen. Crawled under my 2013 truck and didn't see a thermostat. Cooler lines come right out of the transmission on the passenger side, and run their way forward. I have factory tow package with trans cooler.

 

thermostat is only on the 3rd gens.

Next, flip your secondary cooler so inlet and outlet are on the top (or at least 90* so inlet is on the bottom and out is at the top) so the full cooler is actually utilized.

 

My bad, yeah its only on the 3rd gens.

 

I was just driving normal highway 75 deg in San Diego after getting my obd fusion and I hit 200 and was around 180-190. Should I be concerned? No hills no towing.

 

No worries. That's normal bud.

 

what’s a good normal range for 3rd gens and a lower temp threshold to look out for?

 

Third gens have a thermostat and a heat exchanger. The ATF should run about the same as your coolant temps.