Overheating when idle

I've been noticing that the temp gage climbs up quickly if the truck is idling for 5 min or more. It will go from the half way mark to max temp on the gauge in less than 10-15 min. Cools down just as quick as soon as I start driving. Truck has 15,000 kms on it. Clean radiator, air filter, clean engine oil. Could it be a bad thermostat? It's a 2015

 

Sounds like a bad fan clutch. One test for the fan clutch is to watch the fan when you shut the engine off. If it continues to spin a few turns, it's bad.

Could also just be low on coolant. The radiator is going to work less effeciantly when it's only half full.

 

Coolant is full. I'll check the fan when I get home, thanks!

 

sounds like a fan clutch. or REALLY clogged radiator (have you dunked her in muddy water?)

 

Never "dunked" but splashed with muddy water a few times. I always pressure wash it really good after tho. Most likely it's the fan. I'll post again when I confirm...

 

When my radiator was plugged internally I would get an over heat issue while stopped at a traffic light after driving on the Interstate.

 

The fan spins for a second after engine shuts off... should I stick a rolled up newspaper in it to make sure? Is this a safe test? (YouTube suggestion)

 

If you can easily stop the fan with a hot running engine, it's definitely bad. I've stopped them with my hand, but I wasn't going to suggest that you stick your hand in the fan. A rolled up newspaper sounds a lot safer. Give it a try.

When you say spins for a second, is that 1 Missisippi? I don't know that there's a Mississippi spec for that, but 1 Mississippi, 2 Mississippi is definitely bad. It should stop pretty much at the same time the engine stops turning.

 

It's not consistent but seemed to be 1.5-2 seconds on average.

 

If it spins for 2 seconds, with a hot engine, after the motor stops turning, the fan clutch is baaaaaaaad.

 

Yeah that sounds like what happened to me when my stupid e-fans stopped working properly. The temp will start to rise quickly if there's no airflow either from the fan or from driving. Definitely get that checked out, and btw...don't ever let the temp gauge climb toward the red. The gauge only starts to climb once you hit dangerously high temps...if its nearing the red then you might very well be doing damage. Best bet is to get an accurate gauge like a Scangauge or use the Torque app on your phone with an obdii plug.

 

Does your ac stop working as well?

 

What kind of damage are we talking about? the first time I noticed it I left the truck running and went into the house for 20 min(got distracted with my kid) when I came back out it was beyond the red line! The gauge literally couldn't climb any further and it must have been like that for at least 5 minutes!

There was no smoke or vapor coming from anywhere around the engine or radiator! I drove off and it went back down (to the half mark) almost instantly. I checked the engine oil and it was still a fresh golden color and the level was full on the dip stick. Coolant level was right on the full line and the color is still a clear pink as it came from Toyota. That's why I originally thought my issue was a faulty thermostat.

**update on the fan clutch**
So I made an appointment with the dealer to check it out tmw since it's still under warranty. Then I thought I'd better take it to the car wash today to thoroughly clean any signs of mud around the engine so they wouldn't have any excuse to deny warranty. (There was some mud splatter here and there)
while pressure washing the fan with the engine running, the force of the water pressure slowed down the fan to a stop and started turning it in the opposite direction for a bit. (I thought this confirmed the bad clutch idea..) I finished up cleaning it and put some really high pressure on the radiator which looked clean but got some murky water to drip down from it.

Anyway I took it back home let it idle for a bit (15min) and the temp wouldn't rise anymore. I rolled up a piece of card board and tried to stop the fan. It shredded the cardboard. Great. So then I repeatedly stopped the engine while watching the fan. The darn thing looks tight as hell now! It comes to an instant stop with the engine now... every time. As opposed to 2 days ago when I did this same test and watched it spin for at least 1 second after the engine has stopped, several times in a row. Wth happened? The engine was thoroughly warmed up both times. Did I inadvertently tighten up that coil spring by reversing the rotation at the car wash?!

No

 

If there was no smoke or boiling coolant under the hood then you're probably fine, otherwise you could be looking at a headgasket issue in the near future among other things. Makes me wonder if your thermostat is working correctly...if the gauge is in the red that usually means smoking and hissing and boiling

 

You probably had an air pocket in the coolant system, which has since burped out.

I say this based on the fact that your temperature gauge was in the red and it was not blowing steam. In other words it was a false indication due to the air pocket. It wasn't really hot.

 

I can agree with this. Otherwise, your heads would be warped a good .006"+.