How to Replace a Thermostat on an Nissan Carsby Contributing Writer; Updated June 12, 2017
When the thermostat stops working on your Nissan car it will fail-safe. This means the thermostat will fail in a manner that limits the amount of fluid flowing through the engine. The result of a failed thermostat is a lack of heat produced inside of the vehicle. During the summer, the impact is minimal; but during the winter, the driver will be subject to a very cold drive. The only way to correct this is to replace the thermostat by removing it from the intake manifold and replacing it with a new one.
Under The Hood:
- How to Replace a Thermostat on an Xterra
- How to Replace the Thermostat on a 300ZX
- How to Replace the Thermostat on a 91 Nissan Pickup
- How to Change Thermostat in 1995 Nissan Hardbody Truck
- How to Change the Thermostat in a Nissan Pathfinder
- How to Change the Thermostat on a Nissan Frontier
- How to Change the Thermostat in a 2002 Altima
- How to Change the Thermostat in a Nissan Altima
Disconnect the battery.
Remove the lower engine cover and drain the coolant from the radiator.
Remove the engine cooling fan.
Take out the air cleaner and disconnect the air intake duct if you have a four-cylinder Xterra. You may also need to remove the power steering bracket.
Remove the upper radiator hose, if you have a six-cylinder Xterra. Remove the air conditioning belt and the pulley bracket for the idler and detach the lower radiator hose from thermostat's housing unit.
Remove the cover to the thermostat housing unit. Some fluid may spill as the seal is broken.
Remove the thermostat.
Clean off the housing unit by using paint thinner to clean the edges where old gasket residue may remain. Once clean and somewhat dry, apply sealant around the edges of the unit.
Install new thermostat with the valve in the "up" position. Be certain to do so quickly, before the new sealant dries.
Replace the housing unit cover and repeat the installation steps in reverse order; the final step is refilling your radiator with coolant/antifreeze.
Wait at least 30 minutes for the sealant to dry before starting the engine, to avoid possible leaks. Once the engine is started, check for leaks as well as the engine's temperature on the appropriate gauge.
Items you will need
Open the hood to access the coolant system. Place a drain pan under the radiator to catch the old coolant.
Unbolt the coolant temperature sensor at the bottom of the radiator with a socket wrench. The coolant will drain once the sensor is removed. Bolt the sensor back onto the radiator once the radiator has drained.
Unscrew the hose clamps on the upper radiator hose with a flat head screwdriver. Take the hose off the radiator and the thermostat housing.
Remove the three bolts around the thermostat housing with the socket wrench. Remove the top half of the housing by hand.
Scrape the old gasket material off both ends of the housing surface. Ensure all the black gasket material is removed to prevent leaking in the future.
Pull the old thermostat out of the housing by hand. Replace it with a new thermostat. Ensure the spring side of the thermostat goes in first.
Place a new gasket around the surface of the bottom portion of the housing. Place the top half over the bottom half.
Tighten the three bolts to secure the thermostat housing with the socket wrench. Slide the radiator hose onto the thermostat housing and the radiator piping.
Tighten the hose clamps over both ends with a flat head screwdriver. Ensure the hose is on tight by tugging on it to double-check.
Twist the radiator cap counterclockwise and remove it. Pour a gallon of pre-mixed coolant into the radiator.
Start the car to allow it to warm up. Do not put the radiator cap onto the radiator.
Pour in coolant once the level starts dropping. When the thermostat opens, coolant will be released into the engine. Keep pouring until no more coolant will go into the radiator.
Tighten the radiator cap back onto the radiator. Check for any leaks.
Close the hood. Turn off the car.
Items you will need
Flat head screwdriver
New thermostat housing gasket
2 gallons of pre-mixed coolant
Park the 1991 Nissan pickup on a level surface. Set the parking brake and open the hood.
Locate the top radiator hose that runs from the top of the radiator to the engine block. Follow the top radiator hose from the radiator to the thermostat housing. The hose is attached to the thermostat housing tube. Slide the fluid catch pan underneath the engine in the general area of the thermostat housing.
Loosen the hose clamp by turning the adjustable screw head counterclockwise with a flat-head screwdriver. Pull the clamp about 6 inches up onto the radiator hose. Twist the hose back and forth with your hand until it loosens from the thermostat housing tube. Pull the hose straight off the tube.
Loosen and remove the two mounting bolts from the thermostat housing with a ratchet and a socket. Pull the thermostat housing off the engine block and place it on a clean rag.
Pull the thermostat straight up out of the engine block. Scrape any of the old gasket off the base of the thermostat housing and the engine block with a flat scraper. Wipe the thermostat housing base and the engine block clean with a clean rag.
Place the thermostat gasket over the bottom of the thermostat housing base and push the two housing bolts through the holes to hold the gasket in place. Insert the new thermostat into the top of the engine block with the spring facing downward. Lower the housing back over the engine block. Screw the two mounting bolts into the engine block until tight. Finish tightening the bolts with the ratchet and socket.
Push the top radiator hose back over the thermostat housing tube. Position the hose clamp over the hose and over the thermostat housing tube. Tighten the clamp with the screwdriver until the hose is tightly secured to the thermostat housing tube.
Remove the radiator cap and add coolant as needed until the radiator is full. Crank the engine and let it run until the engine is at operating temperature or until the coolant level drops inside of the radiator. This will show that the thermostat is working properly. Inspect the thermostat housing and the top radiator hose for any leaks while the engine is running. Add more coolant if needed to fill the radiator up with the engine running.
Turn the engine off and pull the fluid catch pan out from under the truck.
Items you will need
Fluid catch pan
3/8-inch drive ratchet
3/8-inch drive socket set (metric)
Flat metal scraper
New thermostat with gasket
Raise the front of the Nissan with a floor jack and slide jack stands beneath the vehicle's frame rails. Lower the truck until only the jack stands support its weight.
Slide under the Nissan truck and locate the radiator drain plug under the lower radiator hose -- the rubber hose on the bottom of the radiator. Place the drain pan under the drain plug and remove the plug with a ratchet and socket. Allow all of the coolant to drain into the drain pan.
Reinsert the drain plug and tighten it with a ratchet and socket. Raise the truck from the jack stands with the floor jack, and remove the jack stands. Lower the truck to the ground.
Open the truck's hood.
Locate the upper radiator hose and trace it until you meet the metal housing connecting the hose to the engine, this is the thermostat housing. Remove the three bolts holding the thermostat housing to the engine with a ratchet and socket, and pull the housing away from the engine. This exposes the thermostat below the housing.
Grab the thermostat and pull it from the engine. Insert the new thermostat into the engine with the spring part going into the engine and the jiggle valve -- the small valve on the perimeter of the thermostat -- facing upward.
Scrape the mating surface on the thermostat housing and engine with a plastic gasket scraper to remove the old gasket and any debris. Never scrape these surfaces with a metal scraper, as it may cause damage to the mating surface and result in a leak.
Place a new gasket on the thermostat housing, on the V-6 engine, and press the bolts through the holes in the housing to secure the gasket. Apply a bead of liquid gasket around the mating surface on the four-cylinder engine.
Set the thermostat housing in place over the thermostat and tighten the bolts from 12 to 15 foot-pounds on the V-6 engine and 5 to 6 foot-pounds on the four-cylinder engine, using a torque wrench and socket.
Allow the liquid gasket to dry for approximately 30 minutes on the four-cylinder engine.
Open the radiator cap and fill the radiator with 50-50 premixed coolant. Start the engine and allow it to warm to operating temperature. Add coolant each time the level drops, the coolant should drop three or four times as it circulates through the engine.
Close the radiator cap when the coolant level remains steady and the radiator is full. Shut the engine down.
Allow the engine to cool and check the coolant level in the coolant reservoir. Add 50-50 premixed coolant to the reservoir until it reaches the "Max" line on the reservoir, if needed. The 2.4-liter engine holds a capacity of 2.15 gallons of coolant and the 3.0-liter holds 2.85 gallons.
Close the Nissan's hood.
Take the old coolant to a used automotive fluid recycling center for proper disposal. Most auto parts stores perform this task free of charge.
Items you will need
Plastic gasket scraper
3 gallons 50-50 premixed coolant
Loosen the drain plug at the bottom of the radiator and drain the coolant from your Pathfinder into a suitable container. Reuse the coolant if it is relatively new and clean.
Remove the fan shroud. Follow the upper radiator hose to the intake manifold. Locate the thermostat housing at the point where the radiator hose meets the front of the manifold. Pull off the upper radiator hose from the thermostat housing by loosening the clip at the engine-end of the hose. Remove the lower radiator hose as well.
Take out the two bolts holding the thermostat housing in place. In some Pathfinder models, you may need to remove the drive belts and pulley bracket for easier access to the thermostat housing.
Note the position of the old thermostat. Install the new thermostat into the housing in the same position. Install thermostat gasket. For VG30 engines produced after 1987, Nissan Pathfinders use a liquid gasket rather than a paper gasket. Use a paper gasket for all other Nissan Pathfinder engines.
Reassemble the thermostat housing. Reattach the radiator hose and reinstall the fan shroud. Fill the radiator with reserve or new coolant. Run your Pathfinder with the heater blowing until the engine warms up. Check for leaks.
Items you will need
10mm wrench or socket
Thermostat and paper or liquid gasket
Removal of the Thermostat
Open the hood for access to the engine compartment. Locate the top radiator hose.
Remove the top radiator hose using a flat-head screwdriver. Loosen the hose clamp till the hose can slide off the pipe. Remove the other end of the radiator hose off the thermostat housing assembly.
Locate and remove the two bolts holding the thermostat housing together. Use your socket wrench to remove the top half.
Remove the thermostat with your fingers. The thermostat will lift out with your fingers. Remember the position of the thermostat.
Scrape the old gasket off the thermostat assembly surface. Use a putty knife or a razor blade.
Installation of the Thermostat
Place the new thermostat in the housing. Remember the position of the thermostat that you removed. Install the new thermostat in the same way as the old one.
Place the new gasket on the bottom portion of the assembly. Ensure the bolt holes on the gasket match up to the holes on the gasket.
Place the top of the housing assembly on the bottom portion. Tighten the assembly with your socket wrench. The bolts should be snug to ensure a seal on your gasket.
Install the radiator hose. Be sure to tighten the hose clamps to keep the hose tight on the pipes.
Refill the radiator with coolant. You may have lost some coolant in the thermostat exchange.
Items you will need
Thermostat housing assembly gasket
Locate the thermostat housing by following the radiator hose from the radiator to where it connects to the engine. The metal part that the hose connects to is the thermostat housing. Remove the hose from the housing by squeezing the hose clamp's tabs together and then pull on the hose.
Remove the 10 mm bolts that secure the thermostat housing to the intake manifold of the Altima. Lift the housing off the intake manifold to expose the thermostat gasket and the thermostat.
Lift the thermostat gasket off of the intake manifold and discard it. If you do not see the thermostat gasket on the intake manifold, inspect the bottom of the thermostat housing. It may be stuck there.
Pull the old thermostat out of the intake manifold of the Altima and discard it. Place the new thermostat into the hole with the end marked "top" facing out of the intake.
Place a bead of RTV gasket maker on the bottom edge of the thermostat housing. The silicone in the RTV gasket maker acts as a seal between the thermostat housing and the intake manifold.
Bolt the thermostat housing back onto the intake manifold of the Altima. Do not over-tighten the thermostat housing. Doing so can cause the housing to crack. If the housing does crack, replace with a new one.
Remove the old clamp from the radiator hose and place a band clamp onto the hose. Push the hose onto the thermostat housing and secure the band clamp by tightening it with a screwdriver. The band clamp provides even pressure and will prevent leaks that may occur with the old pressure-style clamp.
Items you will need
10 mm socket and ratchet
RTV silicone gasket maker
Drain the coolant from the radiator and store it in a proper container. Take the negative battery cable from the terminal.
Disconnect the radiator lower hose from the engine coolant inlet side. Take out the engine coolant inlet and the thermostat.
Install the new thermostat with the entire circumference of the flange fitting securely inside the rubber ring. Make sure the jiggle valve is facing up with a deviation of the position plus/minus 10 degrees.
Use Genuine RTV Silicone Sealant or an equivalent product when installing the temperature sensor for the engine coolant. Apply a mild detergent to the O-ring when setting the heater pipe into the housing.
Refill the cooling system with the appropriate type and amount of coolant. Reconnect the battery ground.
Start the engine and allow it to run for several minutes. Check the system for coolant leaks.
Items you will need
Mechanic's toolset, including a full socket set, wrenches and screwdrivers
Replacement thermostat, new or rebuilt
New gasket for thermostat