Proper fluid temps while towing

Recently got my first Tacoma and working on an OBD Fusion dashboard to use while doing occasional towing. Being new to OBD monitors I was wondering what temperature warning ranges folks have used for transmission pan, transmission torque converter, oil temp, and coolant temp. I have a 2020 TRD Off road 3.5L. I have set a warning temp range for each from 195 to 250 degrees but I am sure those are not proper ranges. Any suggestions to use? I would like to be able to glance at the gauges to see if they are approaching the warning range. Below is the iPhone dashboard I am working on.

Thanks for any advice or help.

 

I'm not gonna be a whole lot of help Jim, but I was just the other day reading a thread where a fella's oil temp was in the 240 degree range while towing and was wondering if he should be worried. I think these engines run on the hot side.

Coolant temp should be in the 190 degree range regardless.

Trans temps would be a guess, since I have 3 pedals I'm not aware of where the auto slushbox operates normally but you'll get more to chime in I'm sure.

Welcome aboard!

 

Thanks Nate. Appreciate it!

 

Over the summer I watched my coolant temp and it stayed around 195-200 degrees no matter how I drove

edit: what PIDs did you use for the torque converter temp, pan temp, and the oil temp?

 

Looks like someone posted here in an old thread what I was going to try and type out. Pic below

Having been a automotive tech my entire adult life, much of that at a shop that specialized in transmissions (I did the engine, diagnostics and such mostly, why I was brought in) I can tell you 3 things are the fastest killers of an automatic outside of dumbass abuse.

HEAT is the first above all. Followed by leak causing it to run low, finally not changing your fluid.



For instance, I own a 2003 CRV, 255k untouched engine and transmission. I have beat the hell out of it including 2 years ago towing 1500lbs or so 300 miles from northenr Illinois to st louis, 3 loads. Offroad at what it can handle (nothing like a taco can do), pushing through deep snow, pulling people out of stuck snow banks and so on. Trans still perfect. Still drive it anywhere without concern.

Except for regularly changing the fluid I did one thing I was bummed Toyota did away with on these, A TRANSMISSIOM COOLER.

Towing 1500+ in early June doing 65+mph the hottest my trans got was 225 when I was pushing it.

Look at that graph above, you basically want to keep trans BELOW varnish Temps or change fluid more often to compensate and keep the crap from building up.

 

Thanks much. Appreciate the advice on the transmission cooler. I thought the towing package had a trany cooker but it looks like it it is just engine oil cooler and power steering cooler. I tow a small pop up camper and boat. Both less than 1500 lbs and in flatish Wisconsin. How much is the typical cost to add a trany cooler?

The OBD Fusion pids I am using are all found under the category “Toyota, Lexus, Scion”. A/T oil Temperature No. 1, A/T oil Temperature No. 2, engine oil Temperature, and coolant temperature.

 

Wisconsin flat? Don't think you've ever been to Iowa and Illinois lol. I'm from northwestern Illinois (just moved to STL a year and a half ago). Seemed the farther north I went the less flat it got.

But compared to mountain regions, ya it's pretty flat.

1500lbs up there you should be good, just watch the trans temp on any good climbs. If your not going over 230ish then don't worry about it.

 

I'm gonna give you some free advice...
Throw that mess in the trash, hook up a trailer and tow away.
Why? Several reasons.
1. You or nobody else outside of Toyota actually knows the max operating temp.
2. You don't know where in the engine or transmission the temps are being taken. Temps vary wildly in different parts of the transmission.
3. Lastly, you have no clue the duty cycles so you will have no clue if there is a problem.
All mechanical components have a duty cycle. For example, that engine is designed to run at a certain rpm and temp for X percent of use. It is also designed to run at elevated rpm and temp for Y percent of use and none of us know, so how can you even interpret the temps? Plus, the engine runs in different cycles!

If this was 30 years ago and you installed the sensors then yes, it would be a good idea. Now? Too much tech, too little knowledge.

I tow a lot. None of my warning lights have come on yet and I tow heavy and in mountains and summer. I don't smell coolant nor do I smell a hot or burnt transmission fluid.
Those readers are marketed to people based on ignorance because, even if the readings are higher than what you "feel" are good are they really?

My opinion. Toyota told me my Tacoma could tow 6500 lbs. I know not to tow near limit so when I needed to tow 6500 lbs, I bought a Tundra. Toyota tells me I can now tow 10K, so I know it will pull 6500 lbs just fine.
If I needed to tow 10K, I would get rid of Tundra and get a 3/4 ton to tow.

 

This ^^^^

Too many variables. Outside temp tow weight grade of hill and many more.

 

Thanks everyone. Appreciate the insights and advice. This is all new to me so easy to get lost worrying about the details. My tow weights are pretty low so I will use common sense, follow what the owners manual says, and try not to stress.

 

Good call! In a lot of cases, the phrase "Ignorance is Bliss" is true.
I am an engineer. If I were going in for surgery, even though I could learn about the different heart waves and all the monitoring... it's probably better to just trust those guys.
In these cases, unless you truly understand fluid mechanics and tribology and design duty cycles and mechanical design and Thermodynamics, the numbers you see are just that... numbers.
So have fun, tow and not worry. The only time to worry when towing is when you are maxed out... then you better understand some things.