Thermostat thread

**StockEngine** · May 19th, 2018 02:14 AM

Originally Posted by Archerfish

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.

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.

there is only one temp gauge. yesterday after we got back from punta fuego the engine area was really warm. "radiant heat" this is the warmth im referring to.

the radiant heat was very bad. when we were idling at fronte grabe the engine area you can feel it talaga. when the mech removed the thermostat housing the coolant was steaming. sabi nga ng mech, its looks new! medyo engot lng sya, all thermostats look new in a sealed system(santa fe). then this evening the engine was warm but not as warm. drove from marikina-bgc-marikina for a client meet.

the santa fe has two cooling fans. one for the radiator and one for the condenser. these two were enough to keep the temperature in check but the radiant heat was bad as well as the fc and the AC performance.

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**Archerfish** · May 19th, 2018 02:18 AM

Thank you *dr.d for clarifying the thermostat mixed up knowledge. I seldom get my hands dirty so my knowledge is, just knowledge. So I remember my teacher saying,

"When I work with my hands, I understand."

*oj88, you have answered my long time question about that needle position for the temperature gauge. I've been wondering why it "doesn't move" when the range is between 85 - 110. Thank you.

Now, I think there is another thermostat. The one I mentioned earlier is the one found inside and is in direct contact with the jacket water. I think the other one is the one responsible for turning on and off the radiator fan. I just don't know if it is called normally as a thermostat.

If this thing is no longer working, then there is the probability that the jacket water will reach the boiling point and evaporate since the fan will not be able to cool the radiator.

**StockEngine** · May 19th, 2018 02:19 AM

To add...

I had my Elantra scanned for overheat issues. wala daw, normal kuno! just bought the thermostat and changed it myself. ayun fixed the same issues mentioned. madugo lng coz it required 3+ liters of coolant.

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**ninjababez** · May 19th, 2018 02:32 AM

ano ba ideal mileage na palitan yun thermostat?

**StockEngine** · May 19th, 2018 02:39 AM

Originally Posted by ninjababez

ano ba ideal mileage na palitan yun thermostat?

replace as needed. some just dont know when its needed, hence this thread.

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**kisshmet** · May 19th, 2018 02:44 AM

^wala..just replace it when it fails to function properly..its not fluid that needs to be replaced

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**oj88** · May 19th, 2018 08:39 AM

Originally Posted by Archerfish

Now, I think there is another thermostat. The one I mentioned earlier is the one found inside and is in direct contact with the jacket water. I think the other one is the one responsible for turning on and off the radiator fan. I just don't know if it is called normally as a thermostat.

If this thing is no longer working, then there is the probability that the jacket water will reach the boiling point and evaporate since the fan will not be able to cool the radiator.

Don't mix thermostats with thermoswitches and engine coolant temp sensors.

Thermostat Valve: A mechanical device that is temperature-controlled that starts routing coolant to the radiator (>82°C) or feeds it back to the engine (<80°C) to regulate the coolant temp

Thermoswitch: A mechanical switch that is typically installed at the bottom tank of the radiator which turns on the radiator fan(s) when a certain temp is reached (>85-95°C) and turns off when the temp gets below a certain point (73-75°C)

ECT sensors or temp sender units: The engine coolant temp sensor is an electronic device that varies its internal resistance based on the temperature it's exposed to. The ECU interprets the resistance and converts it to a temperature value that it uses to adjust A/F ratio, idling speed, shift points (A/T), A/C operation, and other engine parameters. You don't typically see the actual value the ECT sensor is giving without an OBDII tool as the ECU abstracts the operation of the temp gauge or temp warning lights. In other words, the temp gauge on your dash is showing what the ECU wants you to see. It does not necessarily reflect the actual temp as seen by the ECT sensor.

Many vehicles don't have a thermoswitch, and instead uses another ECT sensor on the radiator with the ECU commanding the radiator fans when to turn on and off.

**Archerfish** · May 19th, 2018 10:22 AM

Originally Posted by oj88

Don't mix thermostats with thermoswitches and engine coolant temp sensors.

Thermostat Valve: A mechanical device that is temperature-controlled that starts routing coolant to the radiator (>82°C) or feeds it back to the engine (85-95°C) and turns off when the temp gets below a certain point (73-75°C)

ECT sensors or temp sender units: The engine coolant temp sensor is an electronic device that varies its internal resistance based on the temperature it's exposed to. The ECU interprets the resistance and converts it to a temperature value that it uses to adjust A/F ratio, idling speed, shift points (A/T), A/C operation, and other engine parameters. You don't typically see the actual value the ECT sensor is giving without an OBDII tool as the ECU abstracts the operation of the temp gauge or temp warning lights. In other words, the temp gauge on your dash is showing what the ECU wants you to see. It does not necessarily reflect the actual temp as seen by the ECT sensor.

Many vehicles don't have a thermoswitch, and instead uses another ECT sensor on the radiator with the ECU commanding the radiator fans when to turn on and off.

Thank you for taking your time to clarify these things. Yes, I mixed it up because of my simple definition of a thermostat as an instrument that measures temperature and acts like an on-off switch. I think these things are not found in the Owner's Manual. And my guess about this thermoswitch is an RTD.

Now, what is the relationship of this failure in the mechanical thermostat with the jacket water loss as mentioned earlier?