AZ BS Thread 4²0

For OBD Fusion with Toyota PIDs
Transmission PAN: A/T Oil Temperature No. 1
Transmission T/C: A/T Oil Temperature No. 2
T/C Lockup: Lock Up Status

 

Yes, it’s very likely it’s the pan temps. You should look at pinning the thermostat and understanding the torque converter more if you’re seeing those temps.

In 8k miles of towing I never saw pan temps above 203’, this even included pulls over 10,800 ft passes.

What is your rig?

 

Here’s my usual towing dashboard. The red circle top left behind the current gear turns green when the TC is locked.

 

Ahh right, I don’t know too much about the specifics on the 4Runners. Don’t even know if you can pin the thermostat, sorry.

With the Taco I’m happy with pan temps up to 200 and TC up to 230 for short periods.

Check your a/t radiator isn’t full of bugs or beat up with stone chips.

 

I can’t find the thread, but there are two hard lines coming off of the trans that route up to the cooler. They run right next to the cat, and cats run hot as fuck. Wrap the hard lines in some appropriate heat insulation and it will drop your trans temps.

If I can find the thread with actual testing and numbers I’ll post it here.

 

Well that didn’t take long.

https://www.tacomaworld.com/threads/how-to-lower-your-trans-temps.736156/

 

I had thought about making a shroud for my 2020 a/t radiator but I ended up raising it 1.5” from its oem position so it gets better air flow.

I’ll look at possibly insulation the lines near the exhaust if it’s relevant for the 3rd gen. But tbh I find the trans temps are pretty well kept in check as is, even when towing a 5klb brick up mountains.

 

TF2 ranges from 190 to 217 (towing uphill).
TF1 is fairly steady at 200 to 205 most of the time.

I think TF1 is the oil pan sensor, and TF2 is the outlet hose sensor. I might have them reversed...but you get the idea...

 

Lets not forget that water boils at 212° at sea level.
At Phoenix Sky Harbor the altitude is 1,100 asl - water boils at 210°
Black Canyon City is at around 2,000 asl - 208° boil point
The Mogollon Rim runs 5,000 to 5,500 asl - boiling at 202°
Flagstaff is at 7,100 asl - boiling at 199°
And Greer AZ (highest inhabited city in AZ) is at 8,400 - boiling at 196°

Why is that important?
Well, your anti-freeze works to help raise the boil point and lower the freeze point of your trucks coolant (mostly lowers the freeze point) and the radiator cap works to add a few pounds of pressure to the cooling system because that mimics lower altitude and raises the boil point as well. Best you can hope for is that your coolant boil over temp is up around 265° under optimum circumstances. As you increase altitude, that boil point decreases just like water. So if water goes from 212° to 202° at 5,000 asl, then your antifreeze also drops from the optimal best possible case scenario 265° to around 255°. If your coolant is older, it may be 230°.

When your coolant gets near the boil point it gets much less effective. It can't dissipate the heat through the radiator as fast. Compound that with air temps in the 105° range and air coming off the pavement at 120° to 160°. Everything is getting heat soaked. When it hits 115° to 120° here in Phoenix, that pavement air temp can be 180°.

Our engines are also (apparently I'm learning) higher RPM engines. I'm used to making peak HP and torque down low but these Japanese engines make it in the mid to mid high RPM ranges. Faster RPM's means coolant doesn't spend much time in the engine pulling out heat and then it doesn't spend much time in the radiator dissipating heat. Going up the hill, you are likely dropping a gear or two and revving high.

Everything is a part of the equation...
Difference between Air Temp and Boil Temp times the amount of time your coolant spends in the radiator before getting back to the engine = cooling capacity.

Tips to maintain as near to optimum cooling as possible:

• Flush it every two years - needed or not. Our extreme heat KILLS the chemicals and additives they use in cooling systems making them less effective quickly.
• The only water that you ever add to your coolant is distilled. Pure H2O. Never from the garden hose - especially here in the hard water capital of the world.
• When you flush and fill, use the pre-mix and high quality stuff in what ever brand you like. It's made with distilled water.
• I'm not sure if they make one for the 3rd Gen, but if you ever need to replace a radiator, get a high performance all aluminum race radiator. I put one on a 3.3L Nissan V-6 in my old Xterra and it helped a TON.
• Water Wetter is a hotly debated topic. It acts like a surfactant breaking down surface tension in the coolant and allowing coolant to more efficiently "touch" the metal walls to pull heat out of them but it does RAISE your Freeze Point. So if Antifreeze takes you down to -50°, Water Wetter might bring that up significantly to like 10°. I have run it in the past but camping up north in the winter, I worry about freezing the engine.

 

Who wants to loan me 4k.....?

 

Great info.

Is the boiling point of water affected by altitude on a closed loop system that is under considerable more pressure than the surrounding atmosphere?
EDIT: don’t mind me… pressure cap is a valve, DUH.

I had the opposite when pulling a 5klb TT over Wolf Creek Pass (10,800ft elev). My transmission pan temps were steadily climbing when I was in 3rd at 50mph, got to 199 and tc temp to 210’, I dropped to 2nd gear and 45 mph and pan temps dropped to 195’ and tc stayed steady at 207’ for the last mile or so and pan temp got to 190’ at the top. I contributed that to having more fluid running through the radiator extracting more heat.
My rule of thumb is if things are heating up get the fluid moving quicker and keep air flow happening. Pulling over and stopping is potentially the worst thing you can do.

 

I see the same temps with my Scangauge. Went the next step and installed another trans cooler with an electric fan wired to my Auxbeam switch panel. Fan drops temps down to the lower/mid 180s even on freeway. I dont tow anything so have no data for towing.

 

Great info, but to be clear we’re talking about two different systems now. We were discussing transmission temps, not engine temps. But still good info to keep in mind for optimum cooling effectiveness.

 

Zuk provides play by play via text. Rear is done.

 

As long as you’re not seeing pan temps consistently above 205 I wouldn’t stress about it, that’s less than 10% above the thermostat temperature. Thermostat is around 187 ish.

 

$102 Mishimoto MMOC-F Heavy Duty Racing Transmission Cooler, with Electric Fan for Maximum Cooling, Universal Fit

https://www.amazon.com/gp/product/B0035Z3NUG?ie=UTF8

$86 Mishimoto MMFAN-CNTL-U18NPT Adjustable Radiator Fan Controller Kit, Includes NPT Temperature Sensor, Black

https://www.amazon.com/gp/product/B00OBEOXGS?ie=UTF8 These are what I installed , XPOTRPR and I looked into these awhile ago and I pulled the trigger on it. Easy install and worth the addition. Also left my stock cooler in line in front of the new one. Fan on/off can be manual or as to a temp. I have it set to around 207 but usually kick it on way before then. Nice little upgrade for our hot summer temp.

 

yes he does, aint it cool? looks like you popped extra for REM,,, nice, seems like it makes a difference.

 

REM and Cryo. Only thing I couldn’t afford was going with a front E-Locker…for now.

 

i did REM, i didnt cryo, but i did install an ARB locker up front, e locker woulda been nice.

 

Front locker is basically a cheat button for getting through obstacles. Love the Harrop E lockers front and rear