Stuck open thermostat.

These plastic things get very fragile after 8-10 years, the small caliber hose connections simply snap off. I've tried to repair with threaded barb fittings and they don't last. I've replaced numerous of these on Ford Focuses, VW Jettas, and others that I simply cannot remember. Generally though they are cheap and in the $12-$20 range though often they have to be special ordered.
That already problematic plastic water pipe on the back of the engine of the 3.5 is going to become a real issue in about 10 years, if it isn't already, and if the thermostat is not replaceable without replacing that entire plastic housing.......well, whomever came up with that as an acceptable design should simply be tied upside down to a pole after being force-fed exlax.

 

Haha! Yeah I'm used to replacing the simple thermostat itself. God damn toyota screwed us by integrating the thermostat with the housing. Just your typical money grab SMFH....

 

The engine doesn't create much heat at idle. Next time this happens...pop the hood and feel the upper radiator hose. If warm, your tstat is bad. If cold,it's just that your engine isn't creating enough heat when cold.

 

OP, when this happened to you did you get a CEL at all?

I had a similar experience this morning when dropping off a friend at the hospital for a surgery. It was 15 degrees outside. Noticed that even after driving for 20 minutes the temp needle was just barely over the 1/4 mark. Stopped at a light after driving for 30 minutes, sat at light for 2 minutes, and when I drove away from the light the temp needle quickly dropped to the quarter mark. Took roughly 3/4 miles of driving before it returned up to the halfway point.

Did you have any luck with the dealership? Was your thermostat indeed busted?

Thanks!

 

What was the outcome?

 

Sorry guys but I traded my Taco in for a Tundra.....haha