Transmission cooler or not Thread

You ain't gettin' no joy.

 

Yep. I looked up a 2017 manual and checked my 2021 manual. They both say

“To maintain engine braking efficiency and charging system performance when using engine braking, do not use the transmission in D. Transmission shift range position must be in 4 in the S mode.”

Nothing about heat build-up in the TC. It’s all about engine braking.

 

The mechanical fan behind the radiator pulls massive amounts of air through the grille at all times... so yes, even at a stop, the cooler is effective.

 

Maybe this doesn’t matter or can’t be answered, but if the final 10 minutes of towing raises pan temps to 230F due to low driving speeds and trailer repositioning (forward/reverse), is it best then for the transmission to let the truck idle in park for a few minutes or shut it off? Stock setup, no cooler added.

After trailer repositioning, when I shut off the rig and keep the electrical system on, the recorded OBD pan temps stay high. No fluid is moving past the sensor and OBD temps stagnate. If I wait 5 minutes, then start it up and put in gear to move 10’ in my driveway, OBD pan temps show a very rapid drop, presumably just a slug of lower temp fluid moving past the sensor.

I don’t understand the ATF path and cooling processes in relation to the sensor. I also feel like the OBD readings aren’t telling me what’s best for the transmission when fluid isn’t flowing.

Bottom line: Does idling at the end of a “hot” drive on a stock setup do the transmission any good, or best to just shut it down?

 

Its always good to let The Mojo works itself out and Modulate the Temps with a little idle. Foot off brake reduces engine load, too.

 

I would say to let it idle for a little while before shutting it down but I came from the diesel world where that was a must after a long pull to cool down the turbo. It would also let the trans temp come down as well. I haven't towed with the Tundra yet but I will be following the same technique for piece of mind.

 

Saw this article today with a link to Mike Sweers actually talking about the decision to delete the trans cooler. Curious case of missing transmission oil cooler on 2019-2020 Toyota Tundra (pickuptrucktalk.com)

Determined that with Davis Dam J2807 testing the aux cooler wasn't needed, decided removing additional mass would help fuel economy.

We're seeing the same rationale from the other truck manufacturers. As seen by TFL videos both the F150 and the GMC 6.2l have overheated towing in situations below max tow ratings determined by Davis Dam J2807 parameters.

 

No no no no no!!!

Corporate greed is the sole factor! If it was a good idea to have a cooler before then why not now?! I can show you charts from aftermarket transmission parts suppliers circa 1980 that any temperature above 210 means tranny death!!

 

Davis Dam J2807 is at 45 mph. I dont drive at 45 mph. Did you see TFL where his F150 trans and engine overheated. Ford response was it met J2807 which is done at 45 mph. He was going 60mph. Oh and Ford the only one that reduces power so your truck doesn't catch fire. WTF.......................... Oh ford said for every 1000 ft deduct ?% off tow rating. You have to be a mathematician to figure tow rating out. TFL nailed it, below 8K half ton, above 8K 3/4 ton above 12K 1 ton.

 

Except that 3/4 ton and 1 ton are pretty much the same so why even bother with a 3/4 ton?

 

I could not agree more, get the 1 ton!!!!! Makes zero sense to go F250, and F350 only $1500 more. Same drivetrain from F250 to F750.

 

Sure, there was several engineering justifications that went into the decison to delete, Sweers went through them. I think Corporate financial overview contributed to the decision also. 400,000 Sequoias, Tacomas, Tundras built per year, saving $400 per unit, that's $160 million saved per year.

Corporate execs keep their jobs by reducing costs and maximizing profits. Chief Engineers like Sweers keep their jobs by being cooperative with execs to find those reduced costs.

For the Holmesian "Curious Case of the Missing Transmission Cooler" LeStrade would find the superficial clues - J2807 and less mass for fuel savings. Holmes, he would conclude Moriarty/Corporate is pulling the strings and Sweers is the puppet.

I doubt the engineers really wanted to delete the trans cooler, it was a solid design for 20+ years and many millions of miles in the Tacoma, Tundra, Land Cruiser, GX and LX, Sequoia, 4Runner V8.

 

Yeah, J2807 should be updated. When J2807 came out in I think 2008 manufacturers were bragging "We meet J2807!!!"

Now, trucks are meeting J2807 but we're finding out testing to J2807 isn't meeting the realworld when the aux trans coolers are removed.

 

Toyota was the first brand to use j2807 in 2013. Other brands didnt follow suit for a couple-few years.

 

And every engineer I have known will gold plate everything if and when they are given a budget.

A fiscally conscious engineer does not exist.

 

So J2807 was proposed in '08, not implemented til '13 then got widespread 2014+. SAE's Trailer Committee finalized and publish J2807 | Trailer Body Builders (trailer-bodybuilders.com)

I'm seeing some weird things nowadays when manufacturers were bragging about meeting J2807 when they had aux trans coolers, now they're doing the hokey-pokey to justify why they don't need an aux trans cooler.

Davis Dam is a low volume area, few people use it Davis Dam (usbr.gov) so manufacturers can bring their test mules to it and run a J2807. Outdated towing test despite being first implemented in 2013.

What we're seeing is J2807 doesn't amount to shit when the 2013-2018 aux trans coolers are removed.

 

No, what we are seeing is the companys are trying to 1up the other with the ratings. And stay within cafe ratings. J2807 is fine. I have driven that section at least 100 times, a real tourture test is summer. And no your toyota isnt gonna blow its tranny, idk about u nancys tho.

 

You've driven Davis Dam at least 100 times? Towing what lbs? J2807 obviously isn't applicable to realworld in 2021.

 

Has anyone considered the increased demand on the trans fluid pump with the added heat exchanger and components? I would assume to pump is the same from earlier generations that had no problem pushing fluid through an auxiliary cooling system, but friction losses through heat exchangers aren't negligible.

 

I assume the pump is a positive displacement pump if that is the case it will develop whatever pressure necessary to overcome resistance up to it RV setting. I have noticed a substantial decrease in MPG after the cooler installed and the very thick cold transmission fluid...................

 

2019+ trucks have the exact same advertised (and real-world) fuel economy as before. One would think that if Toyota removed it because they didn't need it after all and it's better for fuel economy, we'd see a slightly better fuel economy rating (maybe 14/18 instead of 13/17??) on the 2019+ trucks. One would also think that the numbers on fuelly.com would show a bit of improvement in 2019. But no. In fact, the Tundra's numbers are better for 2009-2014. Maybe this is due to more 4.6L trucks getting slightly better MPG in those years?

All that to say, I think the idea that it improves fuel economy is lame. If it's true and it does, it certainly seems that it's not a measurable difference.

If your fuel economy went down in a measurable way, I would suspect that loss is probably from some other factor.

 

Sorry for the confusion i was being a smart ass on the fuel economy part.

 

I towed a 4500lb open trailer at 65-70 mph yesterday while it was 88F ambient temps, with some hills, a/c full blast. Using the OBDFusion app I never saw pan temps exceed 215F, even when using S5. Is that too hot?

Am I missing something because I swear I saw higher temps unladen in D, with cooler ambient temps going 75+mph.

 

This is without the aux cooler I assume?

 

Correct, bone stock 2020 Tundra.

 

I caught it and was quite pleased.

 

Maybe there's no improvement because of other features added in 2019 that made the truck heavier? Mind you, I can't think of any off hand...

 

I went camping last week , I tow similar load and see exactly the same temps . I tow with s4 and tow haul.
you may see higher while not towing as the torque converter may get unlocked more often depends on your driving .

attached the towing record from my last trip , about an hour long

 

Another data point.

Pulled a tractor home from St Louis to KC yesterday on I-70. Total weight of trailer and tractor was about 5,000 lbs.

Highest pan temp I saw was 208 (briefly). Mostly sat between 199 and 203 entire trip. Peaked on hills.

Ambient temp was 99F and drove about 70MPH when all the trucks weren’t packing everything up.