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2-Regulates the engine's operating temperature: By opening and closing in response to specific changes in coolant temperature to keep the engine's temperature within the desired operating range
THERMOSTAT TEMPERATURES
The thermostat controls the minimum engine temperature, not the maximum, and that coolant under pressure boils at a much greater temperature than water.
Thermostats have a “rated” temperature such as 160F, 180F or 195F
Once the temperature of the coolant rises to between 180 and 195 F (82 - 91 C), the thermostat starts to open, allowing fluid to flow through the radiator. The thermostat simply determines when the cooling system starts to shed heat. By the time the coolant reaches 200 to 218 F (93 - 103 C), the thermostat is open all the way.
Many thermostats have a “jiggle pin” or “check valve” that allows trapped air in the cooling system to pass through the thermostat and be released from the system.
If a thermostat does not have a jiggle pin, it will have a "bleed notch” or other method of removing air from the system.
THERMOSTAT FAILURES
A thermostat fails “open” if the return spring breaks or debris prevents the thermostat valve from fully seating or closing, allowing a steady flow of coolant to the radiator, over cooling the engine
This results in poor warm up and heater performance, increased engine emissions and reduced fuel economy
An engine should never be operated without a thermostat, even in extreme temperatures.
A thermostat will fail “closed” if the internal element has been damaged by overheating (from loss of coolant, a defective electric cooling fan or fan clutch) or corrosion.
This failure prevents the flow of coolant to the radiator, possibly overheating the engine and possibly damaging the engine.
When an engine overheats, it’s a good idea to replace the thermostat because it could be possibly damaged.
OE and ALTERNATE TEMPERATURES
OE recommended temperatures should be used in nearly all situations
Alternate temperature thermostats are available and can be used in some applications
If your engine calls for 180, then go with 180. If it calls for 195F, then run 195F.
Deviating away from the factory thermostat on computer controlled OBD-II engines will cause drivability problems, or even engine troubles down the road.
If your cooling system is working properly, the 160 deg stat will open at approx 160 degrees allowing the cooling system to keep the engine about 160 degrees, too low for proper operation. If the cooling system is inadequate or defective, the cooling system won't be any more able to remove heat with the 160F thermostat than it would with a 180F or 190F
OVERHEATING
If your car overheats with a 180 thermostat it will overheat with a 160 thermostat it will take a little longer for it to happen. The vehicle is overheating because the coolant is not staying in the radiator long enough to maintain a constant temp in the system.
At this point you need to look at the other components such as the radiator possibly clogged. The fan clutch has failed of maybe a 4 bladed fan can be upgraded to a 6 blade to create more air flow. Let’s review the possibilities below
Overheating problems are caused by several things:
1) Inadequate fan
2) Lack of fan shroud
3) Inadequate or clogged radiator
4) Sediment in the engine block restricting heat transfer
5) Contaminated coolant
6) Corroded or broken water pump impeller.
7) Air bound or air bubble (more common in newer vehicles)
8) Collapsed radiator hose ( the internal coil of wire has deteriorated away)
If you are having overheating problems, tackle these things, first. A lower temperature thermostat will not make the car run any cooler just warm up more slowly.