Overheating for a second, then returning to normal temp quickly???

The only times I've had this happen was with a bad t-stat. First showed while towing (240'ish), then was able to watch 10-20* (200-210'ish) warmer temps during daily commutes.

$27 part, 30 minutes, and a few gallons of coolant. Hardest part is getting to the back bolt. This was around 27k miles.

Good luck and report back. The broken cap thread was a big help in troubleshooting, and if the intermittent spikes in temps is proving to consistently be a t-stat, that could help others.

 

Mine did this same thing. Not towing driving kids to school twice in two days. Then none today. Its spikes then goes right back down. I ordered new cap and temp sensor. My truck is a 2014 with 114k miles. We shall see.

 

2015 Tundra Crew Limited 5.7L just started having the same issue. It happened 2 times, about 2-3 weeks apart. Same story, driving on interstate...suddenly the overheat light comes on the dash, as I attempt pull over I see the temp falling and goes back to normal with no light. Not hauling or pulling anything, just 70mph on interstate. I have 195k miles. If anyone found a fix, please post your experience! Thanks!

 

I installed new temp sensor and actually had to add some fluid. Mine was doing the same exact thing. Did that and has not happened since.

 

FOLLOW UP - Problem Fixed!

Changed the coolant temperature sensor! $26.99 at AutoZone and took about 5 minutes to swap! I didn't do anything else. No fluid exchange, no radiator cap swap. I did check my fluid level and radiator cap, both was all good. Thanks so much for all the info here!

I meant to respond sooner but life got me sidetracked!