7 Common Symptoms of a Bad or Failing Thermostat

Common signs and symptoms of a bad engine thermostat and how to test if it has failed.

How To Test an Engine Thermostat with an Infrared Thermometer

How To Test an Engine Thermostat with No Tools Video

Symptoms of a Bad or Failing Thermostat.
High temperature readings (Engine Overheating).
Not heating up when weather is cold.
Coolant fans stay on constantly.
Erratic changes in temperature.
Unusual noises.
Coolant Leaking .
Heater problems.

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[xdsmastermia]

Thanks for the info, my car was acting strange gurgling, now i know why. It overheated

[saren]

My dispatch van takes a while to heat up in the winter and then it overheats only at speed 40mph plus when I put the heating on the overheating needle starts to come down again.. thermostat ?

[midasracer]

When the fan is on all the time it means the fluid in the rad is hot since the switch for the fan is on the rad. This could mean the thermostat doesn't open properly and coolant flow is limited. But could also be a blocked radiator.

[fuzion_nova]

Could it mean a bad gasket if I’m pouring anti freeze in my system and it leaks but also bad heat?

[dalegribble]

You can also have a lazy thermostat even thought the thermostat opens

[shellybelle]

My heating working. It’s not over heating. What should I do?

[wumbnwu]

I am using Lexus ES 300! I change my radiator but since then my temperature will raise above normal and drop back to normal but during the hot wealth/long distance journey, Temperature will raise above normal and fall to normal several times till it’s raises above normal and never return back. I have taken it to different mechanics and electricians but the problem still surface . What might be the problem ?

[FreddyMarothi]

Hi rounalt cleo does have a termostart or not that question is that i have a rounalt cleo 2013 and said stop after said engine filler hazard

[PedroRodriguez-hyty]

How about if your living in a warmer climate let me know thanks

[stephanknubel]

2012 Toyota Tundra...runs fine, temperature has always been fine...but this weekend on highway road trip, notice temperatures rising on "up hills", like a bit more load on the engine. Did not do it all the time, but did it several times on a 400 mile trip. It never overheated, seemed to drop back down after leveling out. This has never done this before. Its not the cap, as I changed it several months ago. Any thoughts....its really bugging me.

[geraldtaylor]

do you have a how to video on changing out the thermostat?

[dewyazzie]

The gurgling noise heard is that when vehicle is on or off?

[karenm]

Have a 1994 Mazda B4000 5 Speed Pickup that keeps running hot but not overheating. Have had the thermostat changed a few times in the truck, so assuming that they go bad often. Upon starting it up, the fan comes on instantly and runs constantly. I have had the entire cooling system done, including replacing a water pump. Radiator has been flushed too. Just having to constantly replace the thermostat seems like there might be something else going on. IDK, any suggestions?

[DbusCollects]

Could it affect the electric power steering?

[JohnSRay-enpi]

what is bad about running a diesel engine cooler than normal because of open thermostat ?

[wmbonjl]

what is the temperature when using the gun on a honda hrv 2020?

[ericrachoene]

My polo vivo shows water sign warning, but water bottle is full of water....whats the problem

[Mruiz]

My heater runs good when driving but not on idle and my temperature gauge reads cold would you say that it is the sensor not the thermostat?

[earthtones]

Yesterday it was extremely hot
My vehicle was revving up on the highway when I accelerated.
Then it started to smell of burnt oil
When I pulled over and shut the vehicle off, I could hear the gurgling sounds.
The AC was not coming on during driving. The highway was very busy due to a holiday, so the vehicles idled most time in line on the roads. (approx 1 hour of crawling traffic)

Anyway, I gave it a 30-minute rest. Sudden rain came down. I guess that cooled things down and I was able to drive safely home.

[paulatuf]

Chrysler 300 2.7 I had the water pump, timing chain, thermostat & reservoir replaced. The vehicle overheats & and the coolant leaks out the reservoir. The mechanic recommends replacing the radiator. What do you think?

Thank you