Transmission Fluid Temperature (vs. 2019 Tahoe)

FL335i · June 1, 2019

I just took my wife's '19 Tahoe out for a good drive this morning. I could not get the temps over 185*F. in slow light driving the temps dropped to 180*F. In my truck my temps run up and stabilize in the 194-196 area. Why would the temps run so much cooler on our '19 Tahoe? Everything is the same.... 5.3L, 3.42 gears, 4WD, same transfercase, same color of vehicle even. What gives. Wondering if GM put a lower temp Tstat on the later models.

1SLOW1500 · June 1, 2019

I just took my wife's '19 Tahoe out for a good drive this morning. I could not get the temps over 185*F. in slow light driving the temps dropped to 180*F. In my truck my temps run up and stabilize in the 194-196 area. Why would the temps run so much cooler on our '19 Tahoe? Everything is the same.... 5.3L, 3.42 gears, 4WD, same transfercase, same color of vehicle even. What gives. Wondering if GM put a lower temp Tstat on the later models.

I would if the tcm is programmed different as well. But I also heard the fleet truck and commercial truck are different. Also I question the difference if any a 6l90e is at.

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Darmichar · June 1, 2019

My 2018 5.3L 3.42 runs 183-185 all day long while driving interstate.

BriDroid · June 1, 2019

17 minutes ago, Darmichar said:

My 2018 5.3L 3.42 runs 183-185 all day long while driving interstate.

Same here, 5.3 6 speed 3.42. I’ve seen 195 in stop/go traffic, but as soon as I get moving it drops back to 180ish.

1SLOW1500 · June 1, 2019

Also I came across a diagram showing the trans lines go into the radiator then out to the condenser then back. However when I bypassed my factory system lines only went to the condenser. Makes sense as the ECT is over 180* in the first mile of driving. Makes me think the newer truck have the better system.

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Gagliano7 · June 5, 2019

I will have to check mine when it gets warmer here. But a month ago when i was towing a trailer of gravel around 2500

lbs my temp only went as high as 185 degrees. It was probably 60 degrees that day. I have a 6.2 8 speed dbl cab.

1SLOW1500 · June 6, 2019

So there is a model change. The earlier trans in this body style ran hotter then the newer trucks. I believe it is because of the trans lines and thermostat. But all the tuning forums speak of this.

FL335i · June 9, 2019

The newer 8speedo r 6speed? I'm leaning heavily to doing the trans T-stat delete.

1SLOW1500 · June 9, 2019

The newer 8speedo r 6speed? I'm leaning heavily to doing the trans T-stat delete.

Well I can only say for sure on the 6 speed. I had the diagram for the trans lines and it showed the radiator then into the top of condenser. But on my truck 2016 it only goes to the condenser. The delete helps a lot. Many are doing them it takes about 20-30 minutes to do.

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duckcommander · June 9, 2019

2015 Silverado 5.3 6 spd ran 195 all the time. 2018 6.2 8 spd runs 175 all the time.

FL335i · June 9, 2019

Well my wife's '19 Z71 Tahoe has the 6spd, not 8. I looked at the trans cooler lines and thermostat vs. mine. It look like they re-designed the line connections and maybe the thermostat itself. So I'm guessing they originally had the 6spd cooking for MPG ratings and to help burn off moisture from short trip use or cold climate use. Then, fast forward 5yrs..... they have the same 6spd running around about 10-15*F cooler. For me, I'm probably going to do the 1/4" NPT thermostat delete. Replacing with the newer Tstat would require replacing the cooler lines to the newer design also. The lines still go through the engine radiator so the ATF would be getting warmed up that way, the conventional way. Plus then my external filter would be working all the time, not just when hot. At the end of the day, removing the t-stat also reduces another failure point. I live in Florida, you need SPF 50 and an umbrella to to check your mailbox, the ATF will warm up just fine.

FL335i · June 15, 2019

Pulled the trigger on doing the T-stat delete. Got a 1/4" NPT tap and brass plug coming my way. Once complete, then I can un-spin the external filter I have and flush the transmission that way.

Edited June 15, 2019 by FL335i

1SLOW1500 · June 16, 2019

I agree it isn't needed. I read the after market 180* bypass thermostat still allows 10% to go to the cooler. Say helps with air pockets and to regulate the fuild wear and temp. The stock doesn't do that but as it heats up it slowly opens.
Also when a future flush is done you do NOT need to get oil up to temp and check it. You can read cold line on dip stick. Or fill till it bleeds out the over flow.
When you do yours. On flat ground start truck and with parking brake on and it idle shift to neutral. The pump will run the whole time and cycle all fluid.
I am performance build and more then double the power and 3 times the clutch but I get up to 150 then a max of 170ish. 180* my fan on the cooler kicks in. This is considered the sweet spot. But still working on air dam and data.

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Ozer · June 17, 2019

I got my trans rebuilt and they did the thermostat delete mod.

Now normal traffic back and forth to work im at 140s.

Highest i got on a mid 80s hot day was 179.

1SLOW1500 · June 17, 2019

I got my trans rebuilt and they did the thermostat delete mod.
Now normal traffic back and forth to work im at 140s.
Highest i got on a mid 80s hot day was 179.

That is great. If you where in tow/haul or really towing it can jump/spike as much as another 20* but still that is a one minute thing and still under 200*. I would suspect that you look at the fluid at 25k and 40k it is still bright red. I would still do the pan drop and refill just to see the magnet and debris out. But your good to go.

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