The automotive thermostat is a temperature controlled on and off valve. When the temperature rises to a predetermined temperature, the thermostat opens up to allow the engine coolant to flow through the cylinder block and the radiator. Contrary to popular opinion, operating the vehicle without the thermostat doesn't make the engine run cooler. It will actually run hotter because there isn't a thermostat to slow the coolant flow. This means the coolant doesn't stay in the radiator long enough to dissipate its heat.
So if thermostat is checked faulty,then its always advisable to replace it.
The details to remove and install the thermostat are as follows :----
Disconnect the negative battery cable.
Drain the cooling system.
CAUTION :--- When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.
Some models require you to remove the air cleaner assembly from the throttle body.
Some models with cruise control have a vacuum modulator attached to the thermostat housing with a bracket. It your vehicle is equipped as such, remove the bracket from the housing.
On the 4-cylinder engines, unbolt the water outlet from the thermostat housing, remove the outlet from the housing and lift the thermostat out of the housing. On all other models, unbolt the water outlet from the intake manifold, remove the outlet and lift the thermostat out of the manifold.
Fig. 1: Loosen the clamp securing the hose to the thermostat housing
Fig. 2: Remove the bolts securing the housing, then pull it away. 
Fig. 3: Make a note as to which end of the thermostat fits in the housing To install:
Clean both of the mating surfaces and run a 1/8 in. (3mm) bead of R.T.V. (Room Temperature Vulcanizing) sealer in the groove of the water outlet.
Fig. 4: Make sure both of the mating surfaces are free of any old gasket material
Install the thermostat (spring towards engine) and bolt the water outlet into place while the R.T.V. sealer is still wet. Tighten the bolts 17-21 ft. lbs. (23-28 Nm) on all but the 2.2L engine. Other engines tighten to 89 inch lbs. (10 Nm).
The remainder of the installation is the reverse of removal. Fill the cooling system, start the engine and top off. Check for leaks after the car is started and correct as required.
How to replace Thermostat on Acura Car models?
Where is thermostat located on 2006 dodge magnum 3.5L?//
Thermostat on AUDI 1.9 TDI?
How to replace Radiator on Audi and VW car models?
How to locate Thermostat on Any car model?
http://schematicsdiagram.blogspot.com/2011/12/how-to-locate-thermostat-on-any-car.html
So if thermostat is checked faulty,then its always advisable to replace it.
The details to remove and install the thermostat are as follows :----
Disconnect the negative battery cable.
Drain the cooling system.
CAUTION :--- When draining the coolant, keep in mind that cats and dogs are attracted by ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.
Some models require you to remove the air cleaner assembly from the throttle body.
Some models with cruise control have a vacuum modulator attached to the thermostat housing with a bracket. It your vehicle is equipped as such, remove the bracket from the housing.
On the 4-cylinder engines, unbolt the water outlet from the thermostat housing, remove the outlet from the housing and lift the thermostat out of the housing. On all other models, unbolt the water outlet from the intake manifold, remove the outlet and lift the thermostat out of the manifold.
Fig. 1: Loosen the clamp securing the hose to the thermostat housing
Clean both of the mating surfaces and run a 1/8 in. (3mm) bead of R.T.V. (Room Temperature Vulcanizing) sealer in the groove of the water outlet.
Fig. 4: Make sure both of the mating surfaces are free of any old gasket material
Install the thermostat (spring towards engine) and bolt the water outlet into place while the R.T.V. sealer is still wet. Tighten the bolts 17-21 ft. lbs. (23-28 Nm) on all but the 2.2L engine. Other engines tighten to 89 inch lbs. (10 Nm).
The remainder of the installation is the reverse of removal. Fill the cooling system, start the engine and top off. Check for leaks after the car is started and correct as required.
For more thermostat related solutions,check the list shown below :----
How to replace Thermostat on Acura Car models?
Where is thermostat located on 2006 dodge magnum 3.5L?//
Thermostat on AUDI 1.9 TDI?
How to replace Radiator on Audi and VW car models?
How to Replace a Thermostat.
