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Virtual Wrench
Virtual Wrench, Master Mechanic
Category: Car
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Experience:  35 years/Master Tech. Foreign and Domestic
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How do I change the thermostat in a 91 Nissan Sentra XE

This answer was rated:

I have already purchased the thermostat, I basically just need to know where it is and a quick how to. Thanks. :)



Can you tell me which engine it has please?

Customer: replied 10 years ago.
Hi. :) Thanks for the response. I hate to sound so dumb but I'm not sure about the engine. Looking at it, it says 2400 and then 12 valve. I will ask my friend whom I bought it from.


No problem, 93% were 1,6 L engine's here are the instructions for that one.


The thermostat is housed in the water outlet casting on the cylinder head on most models. On the GA16DE engines, the thermostat is housed in the water outlet casting attached to the water pump.

  1. Disconnect the negative (-) battery cable.

  2. When cool, open the draincock on the radiator and drain the coolant into a suitable drain pan.

  3. Remove the upper radiator hose from the water outlet side and remove the bolts securing the water outlet to the cylinder head and any other components in the way.

  4. Remove the water outlet and thermostat.

To install:

  1. Clean off the old gasket from the mating surfaces of the thermostat housing and engine block.

When using RTV sealant instead of gaskets, make sure the surface you are working on is very clean before applying the sealant, then apply an even bead. Allow the RTV to dry slightly to form a thin skin. The component MUST be tightened before the RTV dries completely. The bolt torque should be checked again after RTV has completely dried.

  1. When installing the thermostat, be sure to install a new gasket and be sure the air bleed hole in the thermostat is facing upward and that the spring is toward the inside of the engine.

  2. Install the water outlet and tighten the bolts.

    • GA16DE-13-16 ft. lbs. (18-22 Nm)

    • SR20DE-60-72 inch lbs. (6-8 Nm)

  3. If removed, install the exhaust air induction tube clamp bolts.

  4. Install the upper radiator hose, close the draincock and refill the cooling system.

  5. Connect the negative (-) battery cable.

  6. Start the engine and check for leaks



Many engines will have an air relief plug in the cylinder head or near the thermostat housing-

The engine may be damaged if the cooling system is not bled. Air gets trapped in the cylinder head, causing a buildup of heat and pressure.

  1. Fill the radiator with the proper type of coolant.

  2. Loosen the air relief valve in the cylinder head. Fill the engine with coolant until coolant spills out of the valve. If there is no valve, loosen a temperature sender that is nearest the top of the engine. Install the sender when coolant spills from the hole.

  3. With the radiator cap off, start the engine and allow it to run and reach normal operating temperature.

  4. Run the heater at full force and with the temperature lever in the hot position. Be sure that the heater control valve is functioning.

  5. Shut the engine off and recheck the coolant level, refill as necessary.



If you have further questions about this, click on reply. If not, please click on accept.

Thanks for asking!

Happy Holidays!



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