Transmission temp

I have a 2013 Chevy half ton with the 5.3 and 6 speed automatic transmission.it has a transmission temperature display usually running at 140-170 in summertime.at what temperature does damage to the transmission occur? I use it to haul my tractor around locally from time to time

Around 200 225 it really starts to reduce the transmission life

For the most part heat was breaking down the fluid first. Modern spec fluids can handle heat a lot better than older spec fluids, with modern additives and synthetics. Most advertised high temps are around 250*, or at least that's the range most vehicles trigger warning lights or go into failure modes.

What I usually see is trans temp usually is a little cooler than engine temp, but nothing to worry about seeing a little hotter, especially if towing, stop n go, hot days etc.

Before the days of transmission temp gauges on trucks many would place a winter front, grille inserts or cardboard on the front to improve heat inside the cab.

Problem was although you got your engine to run where you wanted it to be temp wise you were blocking all the air flow to your transmission cooler which could not keep up if you were hauling a heavy load.

Why is my fluid so dark?

Back when i had two pick ups with automatic's i installed temp gauges in the pans . The first one was in my 73 F250 that had a few up grades , first was the 360 V8 got pulled and in went a 428 S/CJ then the C6 got reworked and built pressures were increaed stiff firmer shifts and a slight up grade to stall speed Normal driving under 60 Mph with 4.10 gears she would run around 170 on a Stewart and Warner mech gauge , this was with and external and internal coolers . Push it on up to 70 and temps would go up to the 190 range , add a tri axle trailer with load in our humps and bumps it was not un common to see 210 -220 . When plowing heavy snow you could see 240-250 . And due to this you could count on the forward clutch pac failure due to it taking 100 % of the abuse from forward and rev even with 6 disc and plates in that clutch pac. it would take the teeth off the disc. The 78 F250 that started life as a gut less 400 ate five transmissions in four months due to a screw up from the factory as Ford had cheapened up the C6 so bad and someone left out one disc in assembly . when i did the trans myself that is when i found the missing disc and set out to build anothe heavy duty trans from old stock parts i had on hand . The 400 gave way to a 460 and the C6 got built with all three clutch packs with 6 fiber and 6 steel and valve body upgrades . this one also had the exter. and internal coolers and the 4.10 gears and the temps ran close to what the 73 ran and like the 73 i got five years out of that trans before ft clutch failure . I had two pressure gauge and the temp gauges on them .

(quoted from post at 01:46:10 03/02/21) I have a 2013 Chevy half ton with the 5.3 and 6 speed automatic transmission.it has a transmission temperature display usually running at 140-170 in summertime.at what temperature does damage to the transmission occur? I use it to haul my tractor around locally from time to time

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That is just fine.
I believe all auto trannys are plumbed into the radiator.
And some have an additional external cooler.

As long as tranny is no hotter than the "standard" operating temp. of 198 of the engine, all is good.

As a rough general rule , engine temp minus 50 degrees is a base line, hotter than that and the trouble looms. Try to keep it under 200 always.

The guy from Nebraska that could play a guitar, farmed, Transmission specialist, loved IH tractors and his house burnt. I cant remember his name. He once said that at about 211 degrees the lining from the clutch discs start to fall off.

AlleninNeb was his handle.

(quoted from post at 11:57:37 03/02/21) As a rough general rule , engine temp minus 50 degrees is a base line, hotter than that and the trouble looms. Try to keep it under 200 always.

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ot possible with the trans fluid running through the radiator.

(quoted from post at 19:46:57 03/02/21)

(quoted from post at 11:57:37 03/02/21) As a rough general rule , engine temp minus 50 degrees is a base line, hotter than that and the trouble looms. Try to keep it under 200 always.

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ot possible with the trans fluid running through the radiator.

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Exactly!
The rad helps warm up the tranny and then helps keep it going hotter than the engine thermostat.
You would have to have a hefty auxiliary cooler downstream of rad before fluid goes back into tranny.

Yes over 200 and it is not good on em . I remember that guy

The belle in the old dodges would go off at 225 as seen on an external transmission gauge never got that high very often with an oversize transmission pan

Google "Transmission Temperature Chart"
Transmission Temperature Chart