Thermostat thread

**StockEngine** · May 18th, 2018 03:21 PM

Replaced one again. AC is colder. Power improved.

Symptoms: Engine is warmer than normal, Temp gauge didnt move. AC takes 15-30minnutes too cool the cabin. Coolant level dropping. FC was around 6km/L

Fronte Motor Parts - Banawe. scheduling is available. 9am

Look for John

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**baludoy** · May 18th, 2018 05:35 PM

^ what car and how old bro?

Did you use Pure coolant all the way (oem or otherwise)?

do what you gotta do so you can do what you wanna do

**StockEngine** · May 18th, 2018 06:47 PM

Originally Posted by baludoy

^ what car and how old bro?

Did you use Pure coolant all the way (oem or otherwise)?

do what you gotta do so you can do what you wanna do

(2014 Hyundai Elantra 2.0 DIY)

2010 Hyundai Santa fe 2.2 Diesel done at Fronte, Didnt change the coolant yet. konte lng nabawas. topped up with the blue stuff from hyundai. Will flush later on.

AC is cold kahit napaka traffic sa megamall sale [emoji23]

people change radiators and compressors. mas mura naman ang thermostat. [emoji23]

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**Archerfish** · May 19th, 2018 12:22 AM

How do you know that the engine is warmer than normal if the temperature gauge is not moving?

I hope you don't mind explaining the relationship of the coolant level going down with the thermostat.

**dr. d** · May 19th, 2018 12:50 AM

Originally Posted by Archerfish

How do you know that the engine is warmer than normal if the temperature gauge is not moving?

I hope you don't mind explaining the relationship of the coolant level going down with the thermostat.

we don't. because we humans can't. "until it's too late."
that's why the temp gauge is there.

when the thermostat is closed (cold engine), the radiator coolant level is... level.
when the thermostat opens up (when engine gets hot), coolant level will either get higher (if the water pump is pushing coolant up into the radiator), or lower (if the water pump is sucking coolant away from the radiator).

**Archerfish** · May 19th, 2018 01:03 AM

Originally Posted by dr. d

we don't. because we humans can't.
that's why the temp gauge is there.

when the thermostat is closed (cold engine), the radiator coolant level is... level.
when the thermostat opens up (when engine gets hot), coolant level will either get higher (if the water pump is pushing coolant up into the radiator), or lower (if the water pump is sucking coolant away from the radiator).

Yes, however, *Stockengine mentioned that one of the symptoms of a failing thermostat is when the engine is warmer than usual, that is, when the temperature gauge is not moving.

Originally Posted by StockEngine

...

Symptoms: Engine is warmer than normal, Temp gauge didnt move.

...

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Or he is referring to another temperature gauge that I'm not familiar with.

Kindly confirm if my understanding is correct about coolant level. If the thermostat is no longer working properly, in example, not opening, then the coolant level will decrease because it will reach the boiling point and evaporate.

**dr. d** · May 19th, 2018 01:18 AM

when the thermostat gets stuck in the open position, you won't overheat nor loose coolant. your engine will simply take more time to heat up.

when the thermostat gets stuck in the close position, your engine block will overheat and coolant will boil and evaporate. if that superhot coolant boils its way into the radiator, it might result in boiling that coolant away as well, resulting in a diminished radiator coolant level.
if boiling coolant boils into the overflow cannister, that too, shall boil away.

i think he means, some temp sending units are located in places that require moving coolant. those gauges may not correctly give an accurately high reading, if the coolant isn't circulating.

some cars are "intelligent enough", that the aircon compressor shuts down when the engine is overheating.

**oj88** · May 19th, 2018 01:32 AM

No, he means that the temp gauge stays at the same place even if the engine temp varies within its nominal operating temp. It's non-linear.

For most vehicles, the temp gauge stays put in its "normal operating temp" position if the actual coolant temp is between 85°C to 110°C or whereabouts. They made it such so that the driver doesn't panic when the non-graduated temp gauge starts swinging up and down during the course of the trip.

Depending on the vehicle, the temp gauge would only start creeping into the Hot range when the coolant temp gets past the operating temp threshold set inside the ECM. My guess would be 115-120°C onward. At this point, the gauge moves at an exponential rate.

**dr. d** · May 19th, 2018 01:43 AM

Originally Posted by oj88

No, he means that the temp gauge stays at the same place even if the engine temp varies within its nominal operating temp. It's non-linear.

For most vehicles, the temp gauge stays put in its "normal operating temp" position if the actual coolant temp is between 85°C to 110°C or whereabouts. They made it such so that the driver doesn't panic when the non-graduated temp gauge starts swinging up and down during the course of the trip.

Depending on the vehicle, the temp gauge would only start creeping into the Hot range when the coolant temp gets past the operating temp threshold set inside the ECM. My guess would be 115-120°C onward. At this point, the gauge moves at an exponential rate.

i also read his post (#1).
upon reading and re-reading it several times, he probably meant that the temp gauge didn't budge from its overnight cold reading, even as the engine is already noticeably warmer to the touch.

if i may, that is probably true of most cars that still have needle gauges.
my own car's gauge moves up a notch, only after about 1 km.
(but i don't stop to open the hood and feel the engine, to see just how warm it is.)

**oj88** · May 19th, 2018 01:52 AM

Originally Posted by dr. d

i also read his post (#1).
upon reading and re-reading it several times, he probably meant that the temp gauge didn't budge from its overnight cold reading, even as the engine is already noticeably warmer to the touch.

if i may, that is probably true of most cars that still have needle gauges.
my own car's gauge moves up a notch, only after about 1 km.

The TS should be able to clarify what he said.

By my understanding, if you have an OBDII gauge that can read the ECT value, you will see that the operating temperature varies wildly. Even so, the temp gauge on your dashboard remains in the same place (usually just below the 1/2 mark).

So my interpretation of what the TS was saying is that, the ECT value is lower now after the thermostat change.