2016 z71 Silverado 5.3 trans temp help!!!

Rickyace09 · February 10, 2023

So I was having some trans temp concerns in my 2016 z71 silverado. I noticed the temps during the warmer days and stop and go traffic would creep up close to 180-190 and 147 on cooler days. I replaced the thermal bypass valve with the upgraded bulletin one with the 70 print from GM. I don’t haul at all but do a lot of city driving. Should I purchase another thermal bypass to another with the 70 print or if the temps normal??? I know GM said you should only need to change it once unless it’s faulty. But I don’t know if it is or not. I was 64 degrees in Philly today and got up to 178-180 range

Edited February 10, 2023 by Rickyace09

CamGTP · February 10, 2023

A simple test to see how it's working would be to go a route somewhere without lots of city driving.

If the temps stay around 150-170 degrees, then the thermostat is working correctly. Buying a new one at that point wouldn't help any.

If you wish to bypass the thermostat just flip the pill inside the thermostat and it will be open 100% of the time. If the temps continue to still be high after that you have internal transmission problems. Like a slipping torque converter.

Edited February 10, 2023 by CamGTP

16LT4 · February 10, 2023

190* is too hot; even 170* is at the farthest realm of proper. Here's my data points: After I upgraded the GM Thermostat two years ago, I towed my VW 200 miles on a car dolly (crossing NYC) in early August, and never saw trans temps higher than 162*F. This past December, I towed my 442 and my '84 GMC 200 miles each way on a 2k lb u-haul trailer on the same cross-NYC route, and never saw temperatures leave the 140s. This route, in addition to crossing NYC onto Long Island, also includes crossing the Taconic Mountains in upstate NY.