HOW TO CHECK FOR BAD THERMOSTAT

[smartdummy]

If upper radiator hose is hot, your thermostat is at the lower radiator hose and since thermostat is fully shut or not open enough,
coolant can't flow to the radiator to cool down and supply the engine with fresh coolant via the upper radiator hose.
If your lower radiator hose is hot and your upper is cold than you have a thermostat at the upper radiator hose and coolant flows from your bottom radiator hose to top radiator hose.
hot upper = coolant flow bottom to top.
hot lower = coolant flow top to bottom.

Also sometimes the thermostat stays fully open or more than needed. This affects your engine's thermodynamics and power management among other things.
It's better than a stuck closed thermostat but you should still correct a stuck open thermostat ASAP.
In This case, both your hoses will be relatively cold even after driving for sometime or one hose will be colder than normal.

[mack]

Man thank you now I know I bought a bullshit defect thermostat and I appreciate you getting straight to business my brother

[orboakin]

God bless you for this sir. i am fixing up my first car, Pontiac g3 2010, and the fan ia not working and i think the thermostat is to blame. Respect from Nigeria.

[StationRussification]

Beware some vehicles have the t/stats @ the bottom hoses connection & they R installed backwards.

[dannyc]

heres what you do: start car, place hand on hose that has thermostat running to the rad, if after about 10 minutes hose suddenly turns from cold to hot instantly then the thermostat is good. If the hose heats up just gradually then thermostat is stuck open. If the hose never heats up then thermostat is stuck closed.

[Dude_Ness]

seems accurate, can confirm this is true,

[erickbonilla]

My cAr water pump 😢work for a few minutes after that Air is star blowing out from the coolant top and thermostat alway hit up

[robl.]

Cheap enough part better to change it but sometimes it is a pain in the butt to remove

[weirdgamerincxpected]

Never had to check it that way. If temp isnt normal its time to go start checking things. When theres only been coolant in it theres slim to no chance of blockage anywhere. So it'll obviously be the themostat they do get worn out

[tzzcted]

I have corolla the upper hose is getting hot but the bottom one which is connected to the thermostat is cold. Do you think it is stuck closed or what thank you

[ivand]

Is that a Nissan Sentra? Looks like the same motor I had, was 1.6L

[brooklyn]

I have a 04 Honda accord ex 2.4 the top hose gets warm the bottom is cool room temperature that's the thermostat ?

[Dilloz]

Your just trying to rip the customer off for kfc money