overheating at idle

I noticed a few nights ago on the way home my truck was getting up in temp. usually stays at the half way and I was easily 3/4th the way. II notice it climbs when sitting with the ac on.

It's been running great since I got it... 125k miles - p/o has a receipt saying timing belt and water pump was replaced at 107k miles in 2013 along with an antifreeze flush 100 miles earlier. probably going to replace the fluid with toyota long life on next oil change since it is close to 5 years old now.

The only thing I've done recently that might cause this is I dropped trans fluid and refilled and noticed that I took out a LOT more than I put back in, but going by the dipstick it shows right in the middle of cold and hot when cold... Not sure if it was overfilled or if the dipstick isn't a reliable way to check. Could be the reason I'm seeing overheating now.

any ideas??

attached is what my temp gauge was at a few nights ago.. today it was even higher - a few ticks before being in red and it's not even that hot out in TX yet.

edit: today I was between the red and the gauge in the below pic - this pic was taken when I first noticed it on a cool night.

https://imgur.com/a/ofWYNxN

 

So it runs cooler when you’re cruising down the road? Based on your description, it sounds like the viscous fan clutch isn’t engaging.

 

The fan clutch has a TON of resistance. I can barely get it to turn. Would a bad fan clutch spin easily?

 

You’re checking the transmission fluid level in neutral with the engine idling, correct?

 

oh! No. I was checking with the engine cold and in park.

 

Could it be the thermostat not opening all the way?

 

Park is fine too. But the engine has to be idling, and checking it warm is best.

 

When looking at the top of the engine the hose on the right is way hotter than the hose on the left going to and from the radiator. maybe the thermostat is the culprit. I can't give exact temps, but I can hold the left hose while the right hose would be unpleasant to hold.

Btw: The dealership dude told me a drain and fill on the trans was 2.5 qts. I went and checked it and at idle in N it was at the line for cold. I added another quart and it didn't even really go up, but I'll check again tomorrow on a LEVEL GROUND instead of in my driveway. it doesn't seem to go much higher than what the pic shows above.

 

Well, if the rad hoses have a noteable difference in temperature when the gauge is above normal, then the is an issue with flow of coolant from the engine through the rad. A few possibilities are a faulty thermostat not opening, an airlocked cooling system, a bad water pump, or an internally plugged rad.

An infrared thermometer can be VERY useful in situations like this, and they can be had for pretty cheap.

 

pulled the thermostat and it is very hard to open by hand. threw it in 180f water and didn't assuming it is bad. was hoping to run the system without the thermostat until the oem toyota part came in tomorrow, but the thermostat housing leaks without the thermostat/seal intact so I guess I'm gonna run to autozone and grab their stuff and cancel the toyota oem order.... to be continued. I'll let yall know if this solved the problem. I had to drive to and from work today with my head sticking out the window like Ace Ventura with the heater on full blast in the texas heat.

 

Sooooo the autozone thermostat looks SUPER janky compared to the beefy original, but I let the truck idle for 15 mins revving up with ac on full blast and it never budged. I'll monitor it tomorrow commuting and see how she do. If you don't hear back from me the thermostat was the issue.

pics of the old thermostat. definitely seen better days. not sure what that black rubber stuff is at the top - could be what has it caught up.

https://imgur.com/a/qtKW2wl