Transmission Temps??

[COElkFreak]

2018 Tahoe with the 6L80E.

We just had it rebuilt and 1000 miles ago and so far everything is great. My concern in the operating temp. I installed the PPE thermostat bypass. The transmission seems to be running a little cooler around 195-200. I still think that is just too hot for a transmission to run. I know the coolant temp runs around 210 so the tranny fluid will be close. Does anyone else think this is too warm also. I have an add on cooler to add just have not yet. Has anybody ran a colder engine thermostat to bring them temp down? That temps just makes me nervous….my Ram with a 6.7 runs at 165 no matter if I am towing or not.

Thanks as always….Marty

 

[NickTransmissions]

My 6L80 in my truck runs between 185-210 in the summer; otherwise 145-165 when on the road for a while all other seasons.

What temp did it typically run when it was functionally operating normally prior to the rebuild?

 

[Marky Dissod]

... coolant temp runs around 210F, so the ATF will be close. Does anyone else think this is too warm also?

'Too warm'? Nah. It's a bit warmer than I'd LIKE, but anything under 212F is OK.
If you want better than 'OK', you likely prefer this line of thought:

Dexron3 ATF temp behavior
176°F / 80°C . . . . 64,000-96,000 Miles ... Ideal Automatic Transmission Fluid Temp
194°F / 90°C . . . . 32,000-48,000 Miles ... Max Recommended Sustained ATF Temp
212°F / 100°C . . . 16,000-24,000 Miles ... MpG improves, Pressure Drops, longevity / durability decreases
230°F / 110°C . . . . 8,000-12,000 Miles ... Varnishes Form
257°F / 125°C . . . . . 4,000-6,000 Miles ... Seals Harden
275°F / 135°C . . . . . 2,000-3,000 Miles ... Clutches Slip
293°F / 145°C . . . . . 1,000-1,500 Miles ... Oil forms carbon, seals and clutches burn
320°F / 160°C ... ... ... ATF line temp sensor triggers pcm's Hot Transmission Mode

Obviously Dexron6 and the newer ATFs withstand heat better than Dex3, but I'd still replace the ATF if it's indicated temp ever went over 230F,
if only because somewhere, some of the ATF is much hotter than 230F if you're seeing 230F

 

[Doubeleive]

thermostat bypass, transmission deep pan, tru-cool
that should fix you up

 

[tom3]

On our 2019 with a towing package I've never seen a temp over 185 or so and that was in the usual big jam around Atlanta on a real warm day. I did put the lower temp. thermostat on the trans but that wouldn't have much to do with max operating temps.

 

[COElkFreak]

Maybe I’m just won’t thinking it. We use it to pull our two ATV’s and 19” boat and I don’t think either of those is too heavy shift don’t want to be rebuilding it again too soon.

 

[TheBigCheezeBall]

Once i put the surecool bypass in I have never seen higher than 160, and that was on a hot day (95 degrees) in traffic for an hour. I rarely see it over 125 if I am on the highway. Not sure what I would have to do in order to get it to climb to 200 …. I do have the factory tow package which I think adds a cooler next to or in the condenser. If you don’t have this and it only goes into the radiator, I would think an external cooler would help tremendously.

 

[Rygrego]

I kept the newest trans fluid thermostat from GM (154 degrees) and added a Mishimoto transmission cooler and now don't see temps over 165 even towing a 24" tritoon to Lake Havasu, AZ in 115 degree summer.