Towing and Trans Temps

is the electric fan blowing on the cooler or is it pulling the heat away from the cooler? it looks like its blowing towards the cooler?

 

It needs to be blowing onto the cooler the same direction as the airflow while you are moving.

 

its blowing into the cooler

yep.

 

Hey guys, sorry to revive an old thread (great stuff on here btw).

I am researching because I noticed my rpms were a little higher towing our boat on the last fishing trip, so I'm considering an aftermarket trans cooler. I just picked up a Scangauge but wanted to see if anyone had a standard range that the trans temp should be. Also, I used to always tow in D but have seen that folks are saying to tow in 4. Stupid question, but why is that? I'll definitely change to towing in 4 moving forward.

Thanks!

 

towing in 5 is overdrive, you will get much higher trans temps in 5th. so you should always tow in 4th.

 

The transmission fluid deteriorates with higher temperature. I don’t like my pan temp over 220F. Just running around town 160-190F.

 

thanks! I’ll keep an eye on it the next trip when I tow in 4th and can monitor w/ the scan gauge...if it gets over 200 I think I’ll get an aftermarket trans cooler

 

Does anyone know if there is a low temp for atf on 3 gens that might be too low. I pinned the tstat open while towing today and the pan temps dropped by 20* from 188 to 168. I’d like to leave it pinned open but wonder if the atf won’t reach a high enough temp and it might be not a good thing to do.

@gearcruncher ?

 

Honestly if its getting up over 140s I wouldn't worry about it much. I generally see 120-150 unloaded on the highway. Unless you make alot of short trips

 

Thanks, mine levels off to about 185 unloaded and 188-190 when towing. I’ve only seen the tstat open in the 205-210 range which had me wondering if the 3gen synthetic needs to operate normally at the higher temp.

I’m more comfortable with the lower temps and would just like to leave the cooler on line (except for winter). Do you think all the 2gens run cooler than 3gens? Yours appears to.

 

The first half of your question is probably better by @gearcruncher than me.

I have very limited experience on second gens besides my own. Id assume your thermostat is the cause of the higher temps compared to mine. Also not sure where your auxiliary trans cooler is on 3rd gens compared to second gens. Worse comes to worse in the winter you could cover it with cardboard in the winter. I covered my radiator a bit during our winter storm here. It made a difference according to my ultra guage.

 

The transmission fluid goes through the radiator. The nominal trans pan temperature is going to be close to the nominal radiator temperatures.

 

I was just wondering if running at 20* lower than “normal” would cause any problem. It’s a dramatic change when I pin the atf cooler tstat open.

 

Reply a bit late but here goes: My normal under tow (S4+ECT) is 188~193 with occasional spikes in TC temps up to 210.

With ATF cooler t-stat pinned open my normal temps under tow are 168~175 with spikes in TC temp up to 192. I’m leaving it pinned.

Temps monitored with a Scangauge. (3gen)

 

VERY newbie here. Love the info you guys are putting out. I have a manual - besides not towing in 6th, anything special to worry about for periodic towing?

 

Hey all, I read a fair bit of this stuff and finally had my first towing exp. on Saturday. Driving a 3rd gen 4wd with tow package and pulled a 3400 travel tailer from Boise to Portland. I was monitoring the transmission via a bluetooth BAFX module and a tablet. The app (OBD Fusion) offers 2 trans temps (via in app purchase of toyota specific pids) so I monitored both. The first sat around 198 most of the time but would reach as high as 211 on some of the longer uphill climbs. The 2nd was very, very volatile and quickly jump as high as 238 then back down to 198 or so. This 2nd gauge would move so fast I'd go from 200 to 220 within 10-15 seconds on a hill (engine in 3rd gear doing 3500 rpms). Do any of you have any insight what I'm seeing? Those numbers sound really high based on these forums but that doesn't make sense that the truck is kills trans oil within 10 seconds of hitting a hill. What am I missing?

 

The numbers are high but not (Toyota) unusual based on your description of events. When the Torque Converter is unlocked it will produce more heat and you’ll see the spikes on your TF2 gauge. The TF1 temp of 198 is a bit more than I see on mine when towing in S4 @2700 rpm. Mine levels off around 190 mostly flat land.

What I did to lower those temps overall was to pin the ATF cooler T-Stat open. (I think it delays opening on it’s own too long anyway). I’m getting a heat reduction of about 20* with the cooler on line all the time. PAN temp around 170, TC temp spiking to 185 on occasion but quickly returning to “normal” once the TC is locked back up in 4th.

So far so good.

 

@wiljayhi Thanks, I'm taking another trip this weekend so I'll pin the t-stat open and see how it goes. I do run in S4 99% (its drops to S3 when climbing) of the time with ect off as that seems to be what the manual suggests.

 

Run it with ECT on when you’re towing. Better shifting points with the added load. Can't hurt. I do the downshifting manually so I have some control over what gear I’m in if I encounter a hill.

 

Will do, thanks again. I try to do as much research as I can and given this was my first time towing anything I was just feeling a bit overly concerned with all the data not lining up with what I was expecting. Looking forward to this weekend and seeing how the changes impact overall heat.