Probably the engine end of the upper radiator hose
follow the top hose off of your radiator and this is where your thermostat is
where is the fuel filter located would like to see a picture , 1990 Nissan Sentra sedan
The thermostat on a 1995 Nissan Sentra 1.6 is located behind the water inlet. The water inlet is positioned at the end of the lower radiator hose.
The thermostat on a 1989 Nissan Sentra is on the front of the motor to the left. It is just below where the valve cover meets top of the manifold. The thermostat is enclosed in the radiator hose at that location.
I believe it is on the left hand side of the engine, on the firewall side. It is soewhat difficult to get to. You need small hands and patience. This is alwo where the thermostat is located (3 bolts). I believe there is an answer on this site for the thermostat and the sensor is adjacent to it. I considered changing the thermostat, but since it's somehwat complicated, I will leave it to a garage to do it for me.
The thermostat on a 1995 Nissan Sentra 1.6 is located behind the water inlet. The water inlet is positioned at the end of the lower radiator hose.
Look for the thermostat housing on the back side of the block on the upper left-hand side.
The Nissan Sentra thermostat diagram is available from the Nissan service center. This will be provided to you upon request.
Follow the top radiator hose as it connects to the front of the engine. The thermostat is located in that housing.
The thermostat housing is located at the engine end of the lower radiator hose.
It should be right on the valve cover somewhere.
LOCATING THERMOSTAT ON A 1992 NISSAN SENTRA: FACING YOUR CAR THERE IS A HOSE ON THE TOP LEFT SIDE OF THE RADIATOR FOLLOW IT TO ENGINE. THE HOSE ATTACHED TO SMALL HOUSING ON ENGINE BY 2 BOLTS REMOVE AND YOU WILL FIND THE THERMOSTAT. MAKE SURE TO USE NEW GASKET AN GASKET SEALER. Per the repair manual. The thermostat is located from the bottom of the vehicle, off of the lower radiator hose housing. The thermostat "is not" located off of the upper radiator hose behind the housing connected with two bolts.